github.com/Ali-iotechsys/sqlboiler/v4@v4.0.0-20221208124957-6aec9a5f1f71/README.md

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SQLBoiler is a tool to generate a Go ORM tailored to your database schema.

It is a "database-first" ORM as opposed to "code-first" (like gorm/gorp).
That means you must first create your database schema. Please use something
like [sql-migrate](https://github.com/rubenv/sql-migrate)
or some other migration tool to manage this part of the database's life-cycle.

# Note on versions

v1, v2, and v3 are no longer maintained.

v3 is the last GOPATH-compatible version.

v4 has no real breaking changes between v3 and itself other than Go modules
and is the only maintained version. Note this does not work with GOPATH
projects.

## Why another ORM

While attempting to migrate a legacy Rails database, we realized how much ActiveRecord benefited us in terms of development velocity.
Coming over to the Go `database/sql` package after using ActiveRecord feels extremely repetitive, super long-winded and down-right boring.
Being Go veterans we knew the state of ORMs was shaky, and after a quick review we found what our fears confirmed. Most packages out
there are code-first, reflect-based and have a very weak story around relationships between models. So with that we set out with these goals:

* Work with existing databases: Don't be the tool to define the schema, that's better left to other tools.
* ActiveRecord-like productivity: Eliminate all sql boilerplate, have relationships as a first-class concept.
* Go-like feel: Work with normal structs, call functions, no hyper-magical struct tags, small interfaces.
* Go-like performance: [Benchmark](#benchmarks) and optimize the hot-paths, perform like hand-rolled `sql.DB` code.

We believe with SQLBoiler and our database-first code-generation approach we've been able to successfully meet all of these goals. On top
of that SQLBoiler also confers the following benefits:

* The models package is type safe. This means no chance of random panics due to passing in the wrong type. No need for interface{}.
* Our types closely correlate to your database column types. This is expanded by our extended null package which supports nearly all Go data types.
* A system that is easy to debug. Your ORM is tailored to your schema, the code paths should be easy to trace since it's not all buried in reflect.
* Auto-completion provides work-flow efficiency gains.

Table of Contents
=================

  * [SQLBoiler](#sqlboiler)
    * [Why another ORM](#why-another-orm)
    * [About SQL Boiler](#about-sql-boiler)
      * [Features](#features)
      * [Missing Features](#missing-features)
      * [Supported Databases](#supported-databases)
      * [A Small Taste](#a-small-taste)
    * [Requirements & Pro Tips](#requirements--pro-tips)
      * [Requirements](#requirements)
      * [Pro Tips](#pro-tips)
    * [Getting started](#getting-started)
        * [Videos](#videos)
        * [Download](#download)
        * [Configuration](#configuration)
        * [Initial Generation](#initial-generation)
        * [Regeneration](#regeneration)
        * [Controlling Generation](#controlling-generation)
          * [Aliases](#aliases)
          * [Types](#types)
          * [Imports](#imports)
          * [Templates](#templates)
        * [Extending Generated Models](#extending-generated-models)
    * [Diagnosing Problems](#diagnosing-problems)
    * [Features & Examples](#features--examples)
      * [Automatic CreatedAt/UpdatedAt](#automatic-createdatupdatedat)
        * [Skipping Automatic Timestamps](#skipping-automatic-timestamps)
        * [Overriding Automatic Timestamps](#overriding-automatic-timestamps)
      * [Query Building](#query-building)
      * [Query Mod System](#query-mod-system)
      * [Function Variations](#function-variations)
      * [Finishers](#finishers)
      * [Raw Query](#raw-query)
      * [Binding](#binding)
      * [Relationships](#relationships)
      * [Hooks](#hooks)
        * [Skipping Hooks](#skipping-hooks)
      * [Transactions](#transactions)
      * [Debug Logging](#debug-logging)
      * [Select](#select)
      * [Find](#find)
      * [Insert](#insert)
      * [Update](#update)
      * [Delete](#delete)
      * [Upsert](#upsert)
      * [Reload](#reload)
      * [Exists](#exists)
      * [Enums](#enums)
      * [Constants](#constants)
    * [FAQ](#faq)
        * [Won't compiling models for a huge database be very slow?](#wont-compiling-models-for-a-huge-database-be-very-slow)
        * [Missing imports for generated package](#missing-imports-for-generated-package)
        * [How should I handle multiple schemas](#how-should-i-handle-multiple-schemas)
        * [How do I use the types.BytesArray for Postgres bytea arrays?](#how-do-i-use-typesbytesarray-for-postgres-bytea-arrays)
        * [Why aren't my time.Time or null.Time fields working in MySQL?](#why-arent-my-timetime-or-nulltime-fields-working-in-mysql)
        * [Where is the homepage?](#where-is-the-homepage)
        * [Why are the auto-generated tests failing?](#why-are-the-auto-generated-tests-failing)
  * [Benchmarks](#benchmarks)

## About SQL Boiler

### Features

- Full model generation
- Extremely fast code generation
- High performance through generation & intelligent caching
- Uses boil.Executor (simple interface, sql.DB, sqlx.DB etc. compatible)
- Uses context.Context
- Easy workflow (models can always be regenerated, full auto-complete)
- Strongly typed querying (usually no converting or binding to pointers)
- Hooks (Before/After Create/Select/Update/Delete/Upsert)
- Automatic CreatedAt/UpdatedAt
- Automatic DeletedAt
- Table and column whitelist/blacklist
- Relationships/Associations
- Eager loading (recursive)
- Custom struct tags
- Transactions
- Raw SQL fallback
- Compatibility tests (Run against your own DB schema)
- Debug logging
- Basic multiple schema support (no cross-schema support)
- 1d arrays, json, hstore & more
- Enum types
- Out of band driver support
- Support for database views
- Supports generated/computed columns

### Missing features

- Multi-column foreign key support
- Materialized view support

### Supported Databases

| Database          | Driver Location |
| ----------------- | --------------- |
| PostgreSQL        | [https://github.com/volatiletech/sqlboiler/v4/drivers/sqlboiler-psql](drivers/sqlboiler-psql)
| MySQL             | [https://github.com/volatiletech/sqlboiler/v4/drivers/sqlboiler-mysql](drivers/sqlboiler-mysql)
| MSSQLServer 2012+ | [https://github.com/volatiletech/sqlboiler/v4/drivers/sqlboiler-mssql](drivers/sqlboiler-mssql)
| SQLite3           | [https://github.com/volatiletech/sqlboiler/v4/drivers/sqlboiler-sqlite3](drivers/sqlboiler-sqlite3)
| CockroachDB       | https://github.com/glerchundi/sqlboiler-crdb

**Note:** SQLBoiler supports out of band driver support so you can make your own

We are seeking contributors for other database engines.

### A Small Taste

For a comprehensive list of available operations and examples please see [Features & Examples](#features--examples).

```go
import (
  // Import this so we don't have to use qm.Limit etc.
  . "github.com/volatiletech/sqlboiler/v4/queries/qm"
)

// Open handle to database like normal
db, err := sql.Open("postgres", "dbname=fun user=abc")
if err != nil {
  return err
}

// If you don't want to pass in db to all generated methods
// you can use boil.SetDB to set it globally, and then use
// the G variant methods like so (--add-global-variants to enable)
boil.SetDB(db)
users, err := models.Users().AllG(ctx)

// Query all users
users, err := models.Users().All(ctx, db)

// Panic-able if you like to code that way (--add-panic-variants to enable)
users := models.Users().AllP(db)

// More complex query
users, err := models.Users(Where("age > ?", 30), Limit(5), Offset(6)).All(ctx, db)

// Ultra complex query
users, err := models.Users(
  Select("id", "name"),
  InnerJoin("credit_cards c on c.user_id = users.id"),
  Where("age > ?", 30),
  AndIn("c.kind in ?", "visa", "mastercard"),
  Or("email like ?", `%aol.com%`),
  GroupBy("id", "name"),
  Having("count(c.id) > ?", 2),
  Limit(5),
  Offset(6),
).All(ctx, db)

// Use any "boil.Executor" implementation (*sql.DB, *sql.Tx, data-dog mock db)
// for any query.
tx, err := db.BeginTx(ctx, nil)
if err != nil {
  return err
}
users, err := models.Users().All(ctx, tx)

// Relationships
user, err := models.Users().One(ctx, db)
if err != nil {
  return err
}
movies, err := user.FavoriteMovies().All(ctx, db)

// Eager loading
users, err := models.Users(Load("FavoriteMovies")).All(ctx, db)
if err != nil {
  return err
}
fmt.Println(len(users.R.FavoriteMovies))
```

## Requirements & Pro Tips

### Requirements

* Go 1.13, older Go versions are not supported.
* Join tables should use a *composite primary key*.
  * For join tables to be used transparently for relationships your join table must have
  a *composite primary key* that encompasses both foreign table foreign keys and
  no other columns in the table. For example, on a join table named
  `user_videos` you should have: `primary key(user_id, video_id)`, with both
  `user_id` and `video_id` being foreign key columns to the users and videos
  tables respectively and there are no other columns on this table.
* MySQL 5.6.30 minimum; ssl-mode option is not supported for earlier versions.
* For MySQL if using the `github.com/go-sql-driver/mysql` driver, please activate
  [time.Time parsing](https://github.com/go-sql-driver/mysql#timetime-support) when making your
  MySQL database connection. SQLBoiler uses `time.Time` and `null.Time` to represent time in
  it's models and without this enabled any models with `DATE`/`DATETIME` columns will not work.

### Pro Tips

* SQLBoiler generates type safe identifiers for table names, table column names,
  a table's relationship names and type-safe where clauses. You should use these
  instead of strings due to the ability to catch more errors at compile time
  when your database schema changes. See [Constants](#constants) for details.
* It's highly recommended to use transactions where sqlboiler will be doing
  multiple database calls (relationship setops with insertions for example) for
  both performance and data integrity.
* Foreign key column names should end with `_id`.
  * Foreign key column names in the format `x_id` will generate clearer method names.
  It is advisable to use this naming convention whenever it makes sense for your database schema.
* If you never plan on using the hooks functionality you can disable generation of this
  feature using the `--no-hooks` flag. This will save you some binary size.

## Getting started

#### Videos

If you like learning via a video medium, sqlboiler has a number of screencasts
available.

*NOTE:* These videos predate modules (v4), the installation/import paths will be
different though everything else should remain similar.

[SQLBoiler: Getting Started](https://www.youtube.com/watch?v=y5utRS9axfg)

[SQLBoiler: What's New in v3](https://www.youtube.com/watch?v=-B-OPsYRZJA)

[SQLBoiler: Advanced Queries and Relationships](https://www.youtube.com/watch?v=iiJuM9NR8No)

[Old (v2): SQLBoiler Screencast #1: How to get started](https://www.youtube.com/watch?v=fKmRemtmi0Y)

#### Download

First you have to install the code generator binaries. There's the main binary
and then a separate driver binary (select the right one for your database).

Be very careful when installing, there's confusion in the Go ecosystem and
knowing what are the right commands to run for which Go version can be tricky.
Ensure you don't forget any /v suffixes or you'll end up on an old version.

```shell
# Go 1.16 and above:
go install github.com/volatiletech/sqlboiler/v4@latest
go install github.com/volatiletech/sqlboiler/v4/drivers/sqlboiler-psql@latest

# Go 1.15 and below:
# Install sqlboiler v4 and the postgresql driver (mysql, mssql, sqlite3 also available)
# NOTE: DO NOT run this inside another Go module (like your project) as it will
# pollute your go.mod with a bunch of stuff you don't want and your binary
# will not get installed.
GO111MODULE=on go get -u -t github.com/volatiletech/sqlboiler/v4
GO111MODULE=on go get github.com/volatiletech/sqlboiler/v4/drivers/sqlboiler-psql
```

To install `sqlboiler` as a dependency in your project use the commands below
inside of your go module's directory tree. This will install the dependencies
into your `go.mod` file at the correct version.

```shell
# Do not forget the trailing /v4 and /v8 in the following commands
go get github.com/volatiletech/sqlboiler/v4
# Assuming you're going to use the null package for its additional null types
go get github.com/volatiletech/null/v8
```

#### Configuration

Create a configuration file. Because the project uses
[viper](https://github.com/spf13/viper), TOML, JSON and YAML are all usable
but only TOML is supported. Environment variables are also able to be used.

The configuration file should be named `sqlboiler.toml` and is searched for in
the following directories in this order:

- `./`
- `$XDG_CONFIG_HOME/sqlboiler/`
- `$HOME/.config/sqlboiler/`

We will assume TOML for the rest of the documentation.

##### Database Driver Configuration

The configuration for a specific driver (in these examples we'll use `psql`)
must all be prefixed by the driver name. You must use a configuration file or
environment variables for configuring the database driver; there are no
command-line options for providing driver-specific configuration.

In the configuration file for postgresql for example you would do:

```toml
[psql]
dbname = "your_database_name"
```

When you use an environment variable it must also be prefixed by the driver
name:

```sh
PSQL_DBNAME="your_database_name"
```

The values that exist for the drivers:

| Name | Required | Postgres Default | MySQL Default | MSSQL Default |
| ---- | -------- | ---------------- | ------------- | ------------- |
| schema    | no        | "public"  | none   | "dbo"  |
| dbname    | yes       | none      | none   | none   |
| host      | yes       | none      | none   | none   |
| port      | no        | 5432      | 3306   | 1433   |
| user      | yes       | none      | none   | none   |
| pass      | no        | none      | none   | none   |
| sslmode   | no        | "require" | "true" | "true" |
| whitelist | no        | []        | []     | []     |
| blacklist | no        | []        | []     | []     |

Example of whitelist/blacklist:

```toml
[psql]
# Removes migrations table, the name column from the addresses table, and
# secret_col of any table from being generated. Foreign keys that reference tables
# or columns that are no longer generated because of whitelists or blacklists may
# cause problems.
blacklist = ["migrations", "addresses.name", "*.secret_col"]
```

##### Generic config options

You can also pass in these top level configuration values if you would prefer
not to pass them through the command line or environment variables:

| Name                | Defaults  |
| ------------------- | --------- |
| pkgname             | "models"  |
| output              | "models"  |
| tag                 | []        |
| debug               | false     |
| add-global-variants | false     |
| add-panic-variants  | false     |
| add-enum-types      | false     |
| enum-null-prefix    | "Null"    |
| no-context          | false     |
| no-hooks            | false     |
| no-tests            | false     |
| no-auto-timestamps  | false     |
| no-rows-affected    | false     |
| no-driver-templates | false     |
| tag-ignore          | []        |

##### Full Example

```toml
output   = "my_models"
wipe     = true
no-tests = true
add-enum-types = true

[psql]
  dbname = "dbname"
  host   = "localhost"
  port   = 5432
  user   = "dbusername"
  pass   = "dbpassword"
  schema = "myschema"
  blacklist = ["migrations", "other"]

[mysql]
  dbname  = "dbname"
  host    = "localhost"
  port    = 3306
  user    = "dbusername"
  pass    = "dbpassword"
  sslmode = "false"

[mssql]
  dbname  = "dbname"
  host    = "localhost"
  port    = 1433
  user    = "dbusername"
  pass    = "dbpassword"
  sslmode = "disable"
  schema  = "notdbo"
```

#### Initial Generation

After creating a configuration file that points at the database we want to
generate models for, we can invoke the sqlboiler command line utility.

```text
SQL Boiler generates a Go ORM from template files, tailored to your database schema.
Complete documentation is available at http://github.com/volatiletech/sqlboiler

Usage:
  sqlboiler [flags] <driver>

Examples:
sqlboiler psql

Flags:
      --add-global-variants        Enable generation for global variants
      --add-panic-variants         Enable generation for panic variants
      --add-soft-deletes           Enable soft deletion by updating deleted_at timestamp
      --add-enum-types             Enable generation of types for enums
      --enum-null-prefix           Name prefix of nullable enum types (default "Null")
  -c, --config string              Filename of config file to override default lookup
  -d, --debug                      Debug mode prints stack traces on error
  -h, --help                       help for sqlboiler
      --no-auto-timestamps         Disable automatic timestamps for created_at/updated_at
      --no-back-referencing        Disable back referencing in the loaded relationship structs
      --no-context                 Disable context.Context usage in the generated code
      --no-driver-templates        Disable parsing of templates defined by the database driver
      --no-hooks                   Disable hooks feature for your models
      --no-rows-affected           Disable rows affected in the generated API
      --no-tests                   Disable generated go test files
  -o, --output string              The name of the folder to output to (default "models")
  -p, --pkgname string             The name you wish to assign to your generated package (default "models")
      --struct-tag-casing string   Decides the casing for go structure tag names. camel, title, alias or snake (default "snake")
  -t, --tag strings                Struct tags to be included on your models in addition to json, yaml, toml
      --tag-ignore strings         List of column names that should have tags values set to '-' (ignored during parsing)
      --templates strings          A templates directory, overrides the embedded template folders in sqlboiler
      --version                    Print the version
      --wipe                       Delete the output folder (rm -rf) before generation to ensure sanity
```

Follow the steps below to do some basic model generation. Once you've generated
your models, you can run the compatibility tests which will exercise the entirety
of the generated code. This way you can ensure that your database is compatible
with SQLBoiler. If you find there are some failing tests, please check the
[Diagnosing Problems](#diagnosing-problems) section.

```sh
# Generate our models and exclude the migrations table
# When passing 'psql' here, it looks for a binary called
# 'sqlboiler-psql' in your CWD and PATH. You can also pass
# an absolute path to a driver if you desire.
sqlboiler psql

# Run the generated tests
go test ./models
```

*Note: No `mysqldump` or `pg_dump` equivalent for Microsoft SQL Server, so generated tests must be supplemented by `tables_schema.sql` with `CREATE TABLE ...` queries*

You can use `go generate` for SQLBoiler if you want to to make it easy to
run the command for your application:

```go
//go:generate sqlboiler --flags-go-here psql
```

It's important to not modify anything in the output folder, which brings us to
the next topic: regeneration.

#### Regeneration

When regenerating the models it's recommended that you completely delete the
generated directory in a build script or use the `--wipe` flag in SQLBoiler.
The reasons for this are that sqlboiler doesn't try to diff your files in any
smart way, it simply writes the files it's going to write whether they're there
or not and doesn't delete any files that were added by you or previous runs of
SQLBoiler. In the best case this can cause compilation errors, in the worst case
this may leave extraneous and unusable code that was generated against tables
that are no longer in the database.

The bottom line is that this tool should always produce the same result from
the same source. And the intention is to always regenerate from a pure state.
The only reason the `--wipe` flag isn't defaulted to on is because we don't
like programs that `rm -rf` things on the filesystem without being asked to.

#### Controlling Generation

The templates get executed in a specific way each time. There's a variety of
configuration options on the command line/config file that can control what
features are turned on or off.

In addition to the command line flags there are a few features that are only
available via the config file and can use some explanation.

##### Aliases

In sqlboiler, names are automatically generated for you. If you name your
database entities properly you will likely have descriptive names generated in
the end. However in the case where the names in your database are bad AND
unchangeable, or sqlboiler's inference doesn't understand the names you do have
(even though they are good and correct) you can use aliases to change the name
of your tables, columns and relationships in the generated Go code.

*Note: It is not required to provide all parts of all names. Anything left out
will be inferred as it was in the past.*

```toml
# Although team_names works fine without configuration, we use it here for illustrative purposes
[aliases.tables.team_names]
up_plural     = "TeamNames"
up_singular   = "TeamName"
down_plural   = "teamNames"
down_singular = "teamName"

  # Columns can also be aliased.
  [aliases.tables.team_names.columns]
  team_name = "OurTeamName"
```

When creating aliases for relationships, it's important to know how sqlboiler
names relationships. For a given table the foreign key name is used as a unique
identifier to refer to a given relationship. If you are going to be aliasing
relationships it's **highly recommended** that you name your foreign keys
explicitly in your database or the auto-generated names could one day
change/break your aliases.

Each relationship has a **local** and a **foreign** function name. The function name will
be inserted into your generated code as a function to retrieve relationship data as
well as refer to the relationship in a few other places. **local** means "the function name
that refers to the table with the foreign key on it" and conversely **foreign**
means "the function that refers to the table the foreign key points to".

For example - let's have a `videos -> users` many to one relationship that looks
like this:

```text
The tables and their columns:

| videos  | users |
|---------|-------|
| user_id | id    |

Our foreign key:
videos_user_id_fkey: videos.user_id -> users.id
```

In this example `local` (how we refer to the table with the foreign key) is
going to be inferred as `Videos`. We're going to override that below to be
`AuthoredVideos`.

Conversely `foreign` (how we refer to the table the foreign key points to) is
going to be inferred as `User`, which we'd like to rename to `Author` to suit
our domain language a bit better.

With the configuration snippet below we can use the following relationship
helper functions off of the respective models: `video.Author` and
`user.AuthoredVideos` which make a bit more sense than the inferred names when
we see it in the code for our domain. Note the use of the foreign key name to
refer to the relationship in the configuration key.

```toml
[aliases.tables.videos.relationships.videos_author_id_fkey]
# The local side would originally be inferred as AuthorVideos, which
# is probably good enough to not want to mess around with this feature, avoid it where possible.
local   = "AuthoredVideos"
# Even if left unspecified, the foreign side would have been inferred correctly
# due to the proper naming of the foreign key column.
foreign = "Author"
```

In a many-to-many relationship it's a bit more complicated. Let's look at an
example relationship between `videos <-> tags` with a join table in the middle.
Imagine if the join table didn't exist, and instead both of the id columns in
the join table were slapped on to the tables themselves. You'd have
`videos.tag_id` and `tags.video_id`. Using a similar method to the above (local
is the name with which we refer to the side that has the foreign key)
we can rename the relationships. To change `Videos.Tags` to `Videos.Rags`
we can use the example below.

Keep in mind that naming ONE side of the many-to-many relationship is sufficient
as the other side will be automatically mirrored, though you can specify both if
you so choose.

```toml
[aliases.tables.video_tags.relationships.fk_video_id]
local   = "Rags"
foreign = "Videos"
```

The above definition will specify `Rags` as the name of the property with which
a given `Video` entity will be able to access all of it's tags. If we look the
other way around - a single `Tag` entity will refer to all videos that have that
specific tag with the `Videos` property.

There is an alternative syntax available for those who are challenged by the key
syntax of toml or challenged by viper lowercasing all of your keys. Instead of
using a regular table in toml, use an array of tables, and add a name field to
each object. The only one that changes past that is columns, which now has to
have a new field called `alias`.

```toml
[[aliases.tables]]
name          = "team_names"
up_plural     = "TeamNames"
up_singular   = "TeamName"
down_plural   = "teamNames"
down_singular = "teamName"

  [[aliases.tables.columns]]
  name  = "team_name"
  alias = "OurTeamName"

  [[aliases.tables.relationships]]
  name    = "fk_video_id"
  local   = "Rags"
  foreign = "Videos"
```

##### Inflections

With inflections, you can control the rules sqlboiler uses to generates singular/plural variants. This is useful if a certain word or suffix is used multiple times and you do not wnat to create aliases for every instance.

```toml
[inflections.plural]
# Rules to convert a suffix to its plural form
ium = "ia"

[inflections.plural_exact]
# Rules to convert an exact word to its plural form
stadium = "stadia"

[inflections.singular]
# Rules to convert a suffix to its singular form
ia = "ium"

[inflections.singular_exact]
# Rules to convert an exact word to its singular form
stadia = "stadium"

[inflections.irregular]
# The singular -> plural mapping of an exact word that doen't follow conventional rules
radius = "radii"
```

##### Types

There exists the ability to override types that the driver has inferred.
The way to accomplish this is through the config file.

```toml
[[types]]
  # The match is a drivers.Column struct, and matches on almost all fields.
  # Notable exception for the unique bool. Matches are done
  # with "logical and" meaning it must match all specified matchers.
  # Boolean values are only checked if all the string specifiers match first,
  # and they must always match.
  #
  # Not shown here: db_type is the database type and a very useful matcher
  # We can also whitelist tables for this replace by adding to the types.match:
  # tables = ['users', 'videos']
  #
  # Note there is precedence for types.match, more specific things should appear
  # further down in the config as once a matching rule is found it is executed
  # immediately.
  [types.match]
    type = "null.String"
    nullable = true

  # The replace is what we replace the strings with. You cannot modify any
  # boolean values in here. But we could change the Go type (the most useful thing)
  # or the DBType or FullDBType etc. if for some reason we needed to.
  [types.replace]
    type = "mynull.String"

  # These imports specified here overwrite the definition of the type's "based_on_type"
  # list. The type entry that is replaced is the replaced type's "type" field.
  # In the above example it would add an entry for mynull.String, if we did not
  # change the type in our replacement, it would overwrite the null.String entry.
  [types.imports]
    third_party = ['"github.com/me/mynull"']
```

##### Imports

Imports are overridable by the user. This can be used in conjunction with
replacing the templates for extreme cases. Typically this should be avoided.

Note that specifying any section of the imports completely overwrites that
section. It's also true that the driver can still specify imports and those
will be merged in to what is provided here.

```toml
[imports.all]
  standard = ['"context"']
  third_party = ['"github.com/my/package"']

# Changes imports for the boil_queries file
[imports.singleton."boil_queries"]
  standard = ['"context"']
  third_party = ['"github.com/my/package"']

# Same syntax as all
[imports.test]

# Same syntax as singleton
[imports.test_singleton]

# Changes imports when a model contains null.Int32
[imports.based_on_type.string]
  standard = ['"context"']
  third_party = ['"github.com/my/package"']
```

When defining maps it's possible to use an alternative syntax since
viper automatically lowercases all configuration keys (same as aliases).

```toml
[[imports.singleton]]
  name = "boil_queries"
  third_party = ['"github.com/my/package"']

[[imports.based_on_type]]
  name = "null.Int64"
  third_party = ['"github.com/my/int64"']
```

##### Templates

In advanced scenarios it may be desirable to generate additional files that are not go code.
You can accomplish this by using the `--templates` flag to specify **all** the directories you
wish to generate code for. With this flag you specify root directories, that is top-level container
directories.

If root directories have a `_test` suffix in the name, this folder is considered a folder
full of templates for testing only and will be omitted when `--no-tests` is specified and
its templates will be generated into files with a `_test` suffix.

Each root directory is recursively walked. Each template found will be merged into table_name.ext
where ext is defined by the shared extension of the templates. The directory structure is preserved
with the exception of singletons.

For files that should not be generated for each model, you can use a `singleton` directory inside
the directory where the singleton file should be generated. This will make sure that the file is
only generated once.

Here's an example:

```text
templates/
├── 00_struct.go.tpl               # Merged into output_dir/table_name.go
├── 00_struct.js.tpl               # Merged into output_dir/table_name.js
├── singleton
│   └── boil_queries.go.tpl        # Rendered as output_dir/boil_queries.go
└── js
    ├── jsmodel.js.tpl             # Merged into output_dir/js/table_name.js
    └── singleton
        └── jssingle.js.tpl        # Merged into output_dir/js/jssingle.js
```

The output files of which would be:
```
output_dir/
├── boil_queries.go
├── table_name.go
├── table_name.js
└── js
    ├── table_name.js
    └── jssingle.js
```

**Note**: Because the `--templates` flag overrides the embedded templates of `sqlboiler`, if you still
wish to generate the default templates it's recommended that you include the path to sqlboiler's templates
as well.

```toml
templates = [
  "/path/to/sqlboiler/templates",
  "/path/to/sqlboiler/templates_test",
  "/path/to/your_project/more_templates"
]
```

#### Extending generated models

There will probably come a time when you want to extend the generated models
with some kinds of helper functions. A general guideline is to put your
extension functions into a separate package so that your functions aren't
accidentally deleted when regenerating. Past that there are 3 main ways to
extend the models, the first way is the most desirable:

**Method 1: Simple Functions**

```go
// Package modext is for SQLBoiler helper methods
package modext

// UserFirstTimeSetup is an extension of the user model.
func UserFirstTimeSetup(ctx context.Context, db *sql.DB, u *models.User) error { ... }
```

Code organization is accomplished by using multiple files, and everything
is passed as a parameter so these kinds of methods are very easy to test.

Calling code is also very straightforward:

```go
user, err := Users().One(ctx, db)
// elided error check

err = modext.UserFirstTimeSetup(ctx, db, user)
// elided error check
```

**Method 2: Empty struct methods**

The above is the best way to code extensions for SQLBoiler, however there may
be times when the number of methods grows too large and code completion is
not as helpful anymore. In these cases you may consider structuring the code
like this:

```go
// Package modext is for SQLBoiler helper methods
package modext

type users struct {}

var Users = users{}

// FirstTimeSetup is an extension of the user model.
func (users) FirstTimeSetup(ctx context.Context, db *sql.DB, u *models.User) error { ... }
```

Calling code then looks a little bit different:

```go
user, err := Users().One(ctx, db)
// elided error check

err = modext.Users.FirstTimeSetup(ctx, db, user)
// elided error check
```

This is almost identical to the method above, but gives slight amounts more
organization at virtually no cost at runtime. It is however not as desirable
as the first method since it does have some runtime cost and doesn't offer that
much benefit over it.

**Method 3: Embedding**

This pattern is not for the faint of heart, what it provides in benefits it
more than makes up for in downsides. It's possible to embed the SQLBoiler
structs inside your own to enhance them. However it's subject to easy breakages
and a dependency on these additional objects. It can also introduce
inconsistencies as some objects may have no extended functionality and therefore
have no reason to be embedded so you either have to have a struct for each
generated struct even if it's empty, or have inconsistencies, some places where
you use the enhanced model, and some where you do not.

```go
user, err := Users().One(ctx, db)
// elided error check

enhUser := modext.User{user}
err = ehnUser.FirstTimeSetup(ctx, db)
// elided error check
```

I don't recommend this pattern, but included it so that people know it's an
option and also know the problems with it.

## Diagnosing Problems

The most common causes of problems and panics are:

- Forgetting to exclude tables you do not want included in your generation, like migration tables.
- Tables without a primary key. All tables require one.
- Forgetting to put foreign key constraints on your columns that reference other tables.
- The compatibility tests require privileges to create a database for testing purposes, ensure the user
  supplied in your `sqlboiler.toml` config has adequate privileges.
- A nil or closed database handle. Ensure your passed in `boil.Executor` is not nil.
  - If you decide to use the `G` variant of functions instead, make sure you've initialized your
    global database handle using `boil.SetDB()`.
- Naming collisions, if the code fails to compile because there are naming collisions, look at the
  [aliasing](#aliases) feature.
- Race conditions in tests or when using global variable models and using
  relationship set helpers in multiple goroutines. Note that Set/Add/Remove
  relationship helpers modify their input parameters to maintain parity between
  the `.R` struct relationships and the database foreign keys but this can
  produce subtle race conditions. Test for this using the `-race` flag on the
  go tool.
- A field not being inserted (usually a default true boolean), `boil.Infer` looks at the zero
  value of your Go type (it doesn't care what the default value in the database is) to determine
  if it should insert your field or not. In the case of a default true boolean value, when you
  want to set it to false; you set that in the struct but that's the zero value for the bool
  field in Go so sqlboiler assumes you do not want to insert that field and you want the default
  value from the database. Use a whitelist/greylist to add that field to the list of fields
  to insert.
- decimal library showing errors like: `pq: encode: unknown type types.NullDecimal`
  is a result of a too-new and broken version of the github.com/ericlargergren/decimal
  package, use the following version in your go.mod:
  github.com/ericlagergren/decimal v0.0.0-20181231230500-73749d4874d5

For errors with other causes, it may be simple to debug yourself by looking at the generated code.
Setting `boil.DebugMode` to `true` can help with this. You can change the output using `boil.DebugWriter` (defaults to `os.Stdout`).

If you're still stuck and/or you think you've found a bug, feel free to leave an issue and we'll do our best to help you.

## Features & Examples

Most examples in this section will be demonstrated using the following Postgres schema, structs and variables:

```sql
CREATE TABLE pilots (
  id integer NOT NULL,
  name text NOT NULL
);

ALTER TABLE pilots ADD CONSTRAINT pilot_pkey PRIMARY KEY (id);

CREATE TABLE jets (
  id integer NOT NULL,
  pilot_id integer NOT NULL,
  age integer NOT NULL,
  name text NOT NULL,
  color text NOT NULL
);

ALTER TABLE jets ADD CONSTRAINT jet_pkey PRIMARY KEY (id);
ALTER TABLE jets ADD CONSTRAINT jet_pilots_fkey FOREIGN KEY (pilot_id) REFERENCES pilots(id);

CREATE TABLE languages (
  id integer NOT NULL,
  language text NOT NULL
);

ALTER TABLE languages ADD CONSTRAINT language_pkey PRIMARY KEY (id);

-- Join table
CREATE TABLE pilot_languages (
  pilot_id integer NOT NULL,
  language_id integer NOT NULL
);

-- Composite primary key
ALTER TABLE pilot_languages ADD CONSTRAINT pilot_language_pkey PRIMARY KEY (pilot_id, language_id);
ALTER TABLE pilot_languages ADD CONSTRAINT pilot_language_pilots_fkey FOREIGN KEY (pilot_id) REFERENCES pilots(id);
ALTER TABLE pilot_languages ADD CONSTRAINT pilot_language_languages_fkey FOREIGN KEY (language_id) REFERENCES languages(id);
```

The generated model structs for this schema look like the following. Note that we've included the relationship
structs as well so you can see how it all pieces together:

```go
type Pilot struct {
  ID   int    `boil:"id" json:"id" toml:"id" yaml:"id"`
  Name string `boil:"name" json:"name" toml:"name" yaml:"name"`

  R *pilotR `boil:"-" json:"-" toml:"-" yaml:"-"`
  L pilotR  `boil:"-" json:"-" toml:"-" yaml:"-"`
}

type pilotR struct {
  Languages LanguageSlice
  Jets      JetSlice
}

type Jet struct {
  ID      int    `boil:"id" json:"id" toml:"id" yaml:"id"`
  PilotID int    `boil:"pilot_id" json:"pilot_id" toml:"pilot_id" yaml:"pilot_id"`
  Age     int    `boil:"age" json:"age" toml:"age" yaml:"age"`
  Name    string `boil:"name" json:"name" toml:"name" yaml:"name"`
  Color   string `boil:"color" json:"color" toml:"color" yaml:"color"`

  R *jetR `boil:"-" json:"-" toml:"-" yaml:"-"`
  L jetR  `boil:"-" json:"-" toml:"-" yaml:"-"`
}

type jetR struct {
  Pilot *Pilot
}

type Language struct {
  ID       int    `boil:"id" json:"id" toml:"id" yaml:"id"`
  Language string `boil:"language" json:"language" toml:"language" yaml:"language"`

  R *languageR `boil:"-" json:"-" toml:"-" yaml:"-"`
  L languageR  `boil:"-" json:"-" toml:"-" yaml:"-"`
}

type languageR struct {
  Pilots PilotSlice
}
```

```go
// Open handle to database like normal
db, err := sql.Open("postgres", "dbname=fun user=abc")
if err != nil {
  return err
}
```

### Automatic CreatedAt/UpdatedAt

If your generated SQLBoiler models package can find columns with the
names `created_at` or `updated_at` it will automatically set them
to `time.Now()` in your database, and update your object appropriately.
To disable this feature use `--no-auto-timestamps`.

Note: You can set the timezone for this feature by calling `boil.SetLocation()`

#### Customizing the timestamp columns

Set the `auto-columns` map in your configuration file

```toml
[auto-columns]
    created = "createdAt"
    updated = "updatedAt"
```

#### Skipping Automatic Timestamps

If for a given query you do not want timestamp columns to be re-computed prior
to an insert or update then you can use `boil.SkipTimestamps` on the context you
pass in to the query to prevent them from being updated.

Keep in mind this has no effect on whether or not the column is included in the
insert/update, it simply stops them from being set to `time.Now()` in the struct
before being sent to the database (if they were going to be sent).

#### Overriding Automatic Timestamps

* **Insert**
  * Timestamps for both `updated_at` and `created_at` that are zero values will be set automatically.
  * To set the timestamp to null, set `Valid` to false and `Time` to a non-zero value.
  This is somewhat of a work around until we can devise a better solution in a later version.
* **Update**
  * The `updated_at` column will always be set to `time.Now()`. If you need to override
  this value you will need to fall back to another method in the meantime: `queries.Raw()`,
  overriding `updated_at` in all of your objects using a hook, or create your own wrapper.
* **Upsert**
  * `created_at` will be set automatically if it is a zero value, otherwise your supplied value
  will be used. To set `created_at` to `null`, set `Valid` to false and `Time` to a non-zero value.
  * The `updated_at` column will always be set to `time.Now()`.

### Automatic DeletedAt (Soft Delete)

Soft deletes are a way of deleting records in a database for the average query
without actually removing the data. This type of thing is important in certain
scenarios where data retention is important. It is typically done by adding a
`deleted` bool or a `deleted_at` timestamp to each table in the database
that can be soft deleted and subsequent queries on that table should always
make sure that `deleted != true` or `deleted_at is null` to prevent showing
"deleted" data.

SQLBoiler uses the `deleted_at` variant to provide this functionality. If your
table has a nullable timestamp field named `deleted_at` it will be a candidate
for soft-deletion.

*NOTE*: As of writing soft-delete is opt-in via `--add-soft-deletes` and is
liable to change in future versions.

*NOTE*: There is a query mod to bypass soft delete for a specific query by using
`qm.WithDeleted`, note that there is no way to do this for Exists/Find helpers
yet.

*NOTE*: The `Delete` helpers will _not_ set `updated_at` currently. The current
philosophy is that deleting the object is simply metadata and since it returns
in no queries (other than raw ones) the updated_at will no longer be relevant.
This could change in future versions if people disagree with this but it is
the current behavior.

### Query Building

We generate "Starter" methods for you. These methods are named as the plural versions of your model,
for example: `models.Jets()`. Starter methods are used to build queries using our
[Query Mod System](#query-mod-system). They take a slice of [Query Mods](#query-mod-system)
as parameters, and end with a call to a [Finisher](#finishers) method.

Here are a few examples:

```go
// SELECT COUNT(*) FROM pilots;
count, err := models.Pilots().Count(ctx, db)

// SELECT * FROM "pilots" LIMIT 5;
pilots, err := models.Pilots(qm.Limit(5)).All(ctx, db)

// DELETE FROM "pilots" WHERE "id"=$1;
err := models.Pilots(qm.Where("id=?", 1)).DeleteAll(ctx, db)
// type safe version of above
err := models.Pilots(models.PilotWhere.ID.EQ(1)).DeleteAll(ctx, db)
```

In the event that you would like to build a query and specify the table yourself, you
can do so using `models.NewQuery()`:

```go
// Select all rows from the pilots table by using the From query mod.
err := models.NewQuery(db, qm.From("pilots")).All(ctx, db)
```

As you can see, [Query Mods](#query-mod-system) allow you to modify your
queries, and [Finishers](#finishers) allow you to execute the final action.

We also generate query building helper methods for your relationships as well. Take a look at our
[Relationships Query Building](#relationships) section for some additional query building information.

### Query Mod System

The query mod system allows you to modify queries created with
[Starter](#query-building) methods when performing query building.
See examples below.

**NOTE:** SQLBoiler generates type-safe identifiers based on your database
tables, columns and relationships. Using these is a bit more verbose, but is
especially safe since when the names change in the database the generated
code will be different causing compilation failures instead of runtime
errors. It is highly recommended you use these instead of regular strings.
See [Constants](#constants) for more details.

**NOTE:** You will notice that there is printf used below mixed with SQL
statements. This is normally NOT OK if the user is able to supply any of
the sql string, but here we always use a `?` placeholder and pass arguments
so that the only thing that's being printf'd are constants which makes it
safe, but be careful!

```go
// Dot import so we can access query mods directly instead of prefixing with "qm."
import . "github.com/volatiletech/sqlboiler/v4/queries/qm"

// Use a raw query against a generated struct (Pilot in this example)
// If this query mod exists in your call, it will override the others.
// "?" placeholders are not supported here, use "$1, $2" etc.
SQL("select * from pilots where id=$1", 10)
models.Pilots(SQL("select * from pilots where id=$1", 10)).All()

Select("id", "name") // Select specific columns.
Select(models.PilotColumns.ID, models.PilotColumns.Name)
From("pilots as p") // Specify the FROM table manually, can be useful for doing complex queries.
From(models.TableNames.Pilots + " as p")

// WHERE clause building
Where("name=?", "John")
models.PilotWhere.Name.EQ("John")
And("age=?", 24)
// No equivalent type safe query yet
Or("height=?", 183)
// No equivalent type safe query yet

Where("(name=? and age=?) or (age=?)", "John", 5, 6)
// Expr allows manual grouping of statements
Where(
  Expr(
    models.PilotWhere.Name.EQ("John"),
    Or2(models.PilotWhere.Age.EQ(5)),
  ),
  Or2(models.PilotAge),
)

// WHERE IN clause building
WhereIn("name, age in ?", "John", 24, "Tim", 33) // Generates: WHERE ("name","age") IN (($1,$2),($3,$4))
WhereIn(fmt.Sprintf("%s, %s in ?", models.PilotColumns.Name, models.PilotColumns.Age, "John", 24, "Tim", 33))
AndIn("weight in ?", 84)
AndIn(models.PilotColumns.Weight + " in ?", 84)
OrIn("height in ?", 183, 177, 204)
OrIn(models.PilotColumns.Height + " in ?", 183, 177, 204)

InnerJoin("pilots p on jets.pilot_id=?", 10)
InnerJoin(models.TableNames.Pilots + " p on " + models.TableNames.Jets + "." + models.JetColumns.PilotID + "=?", 10)

GroupBy("name")
GroupBy("name like ? DESC, name", "John")
GroupBy(models.PilotColumns.Name)
OrderBy("age, height")
OrderBy(models.PilotColumns.Age, models.PilotColumns.Height)

Having("count(jets) > 2")
Having(fmt.Sprintf("count(%s) > 2", models.TableNames.Jets)

Limit(15)
Offset(5)

// Explicit locking
For("update nowait")

// Common Table Expressions
With("cte_0 AS (SELECT * FROM table_0 WHERE thing=$1 AND stuff=$2)")

// Eager Loading -- Load takes the relationship name, ie the struct field name of the
// Relationship struct field you want to load. Optionally also takes query mods to filter on that query.
Load("Languages", Where(...)) // If it's a ToOne relationship it's in singular form, ToMany is plural.
Load(models.PilotRels.Languages, Where(...))
```

Note: We don't force you to break queries apart like this if you don't want to, the following
is also valid and supported by query mods that take a clause:

```go
Where("(name=? OR age=?) AND height=?", "John", 24, 183)
```

### Function Variations

Functions can have variations generated for them by using the flags
`--add-global-variants` and `--add-panic-variants`. Once you've used these
flags or set the appropriate values in your configuration file extra method
overloads will be generated. We've used the `Delete` method to demonstrate:

```go
// Set the global db handle for G method variants.
boil.SetDB(db)

pilot, _ := models.FindPilot(ctx, db, 1)

err := pilot.Delete(ctx, db) // Regular variant, takes a db handle (boil.Executor interface).
pilot.DeleteP(ctx, db)       // Panic variant, takes a db handle and panics on error.
err := pilot.DeleteG(ctx)    // Global variant, uses the globally set db handle (boil.SetDB()).
pilot.DeleteGP(ctx)          // Global&Panic variant, combines the global db handle and panic on error.

db.Begin()                   // Normal sql package way of creating a transaction
boil.BeginTx(ctx, nil)       // Uses the global database handle set by boil.SetDB() (doesn't require flag)
```

Note that it's slightly different for query building.

### Finishers

Here are a list of all of the finishers that can be used in combination with
[Query Building](#query-building).

Finishers all have `P` (panic) [method variations](#function-variations). To specify
your db handle use the `G` or regular variation of the [Starter](#query-building) method.

```go
// These are called like the following:
models.Pilots().All(ctx, db)

One() // Retrieve one row as object (same as LIMIT(1))
All() // Retrieve all rows as objects (same as SELECT * FROM)
Count() // Number of rows (same as COUNT(*))
UpdateAll(models.M{"name": "John", "age": 23}) // Update all rows matching the built query.
DeleteAll() // Delete all rows matching the built query.
Exists() // Returns a bool indicating whether the row(s) for the built query exists.
Bind(&myObj) // Bind the results of a query to your own struct object.
Exec() // Execute an SQL query that does not require any rows returned.
QueryRow() // Execute an SQL query expected to return only a single row.
Query() // Execute an SQL query expected to return multiple rows.
```

### Raw Query

We provide `queries.Raw()` for executing raw queries. Generally you will want to use `Bind()` with
this, like the following:

```go
err := queries.Raw("select * from pilots where id=$1", 5).Bind(ctx, db, &obj)
```

You can use your own structs or a generated struct as a parameter to Bind. Bind supports both
a single object for single row queries and a slice of objects for multiple row queries.

`queries.Raw()` also has a method that can execute a query without binding to an object, if required.

You also have `models.NewQuery()` at your disposal if you would still like to use [Query Building](#query-building)
in combination with your own custom, non-generated model.

### Binding

For a comprehensive ruleset for `Bind()` you can refer to our [pkg.go.dev](https://pkg.go.dev/github.com/volatiletech/sqlboiler/v4/queries#Bind).

The `Bind()` [Finisher](#finisher) allows the results of a query built with
the [Raw SQL](#raw-query) method or the [Query Builder](#query-building) methods to be bound
to your generated struct objects, or your own custom struct objects.

This can be useful for complex queries, queries that only require a small subset of data
and have no need for the rest of the object variables, or custom join struct objects like
the following:

```go
// Custom struct using two generated structs
type PilotAndJet struct {
  models.Pilot `boil:",bind"`
  models.Jet   `boil:",bind"`
}

var paj PilotAndJet
// Use a raw query
err := queries.Raw(`
  select pilots.id as "pilots.id", pilots.name as "pilots.name",
  jets.id as "jets.id", jets.pilot_id as "jets.pilot_id",
  jets.age as "jets.age", jets.name as "jets.name", jets.color as "jets.color"
  from pilots inner join jets on jets.pilot_id=?`, 23,
).Bind(ctx, db, &paj)

// Use query building
err := models.NewQuery(
  Select("pilots.id", "pilots.name", "jets.id", "jets.pilot_id", "jets.age", "jets.name", "jets.color"),
  From("pilots"),
  InnerJoin("jets on jets.pilot_id = pilots.id"),
).Bind(ctx, db, &paj)
```

```go
// Custom struct for selecting a subset of data
type JetInfo struct {
  AgeSum int `boil:"age_sum"`
  Count int `boil:"juicy_count"`
}

var info JetInfo

// Use query building
err := models.NewQuery(Select("sum(age) as age_sum", "count(*) as juicy_count", From("jets"))).Bind(ctx, db, &info)

// Use a raw query
err := queries.Raw(`select sum(age) as "age_sum", count(*) as "juicy_count" from jets`).Bind(ctx, db, &info)
```

We support the following struct tag modes for `Bind()` control:

```go
type CoolObject struct {
  // Don't specify a name, Bind will TitleCase the column
  // name, and try to match against this.
  Frog int

  // Specify an alternative name for the column, it will
  // be titlecased for matching, can be whatever you like.
  Cat int  `boil:"kitten"`

  // Ignore this struct field, do not attempt to bind it.
  Pig int  `boil:"-"`

  // Instead of binding to this as a regular struct field
  // (like other sql-able structs eg. time.Time)
  // Recursively search inside the Dog struct for field names from the query.
  Dog      `boil:",bind"`

  // Same as the above, except specify a different table name
  Mouse    `boil:"rodent,bind"`

  // Ignore this struct field, do not attempt to bind it.
  Bird     `boil:"-"`
}
```

### Relationships

Helper methods will be generated for every to one and to many relationship structure
you have defined in your database by using foreign keys.

We attach these helpers directly to your model struct, for example:

```go
jet, _ := models.FindJet(ctx, db, 1)

// "to one" relationship helper method.
// This will retrieve the pilot for the jet.
pilot, err := jet.Pilot().One(ctx, db)

// "to many" relationship helper method.
// This will retrieve all languages for the pilot.
languages, err := pilot.Languages().All(ctx, db)
```

If your relationship involves a join table SQLBoiler will figure it out for you transparently.

It is important to note that you should use `Eager Loading` if you plan
on loading large collections of rows, to avoid N+1 performance problems.

For example, take the following:

```go
// Avoid this loop query pattern, it is slow.
jets, _ := models.Jets().All(ctx, db)
pilots := make([]models.Pilot, len(jets))
for i := 0; i < len(jets); i++ {
  pilots[i] = jets[i].Pilot().OneP(ctx, db)
}

// Instead, use Eager Loading!
jets, _ := models.Jets(Load("Pilot")).All(ctx, db)
// Type safe relationship names exist too:
jets, _ := models.Jets(Load(models.JetRels.Pilot)).All(ctx, db)

// Then access the loaded structs using the special Relation field
for _, j := range jets {
  _ = j.R.Pilot
}
```

Eager loading can be combined with other query mods, and it can also eager load recursively.

```go
// Example of a nested load.
// Each jet will have its pilot loaded, and each pilot will have its languages loaded.
jets, _ := models.Jets(Load("Pilot.Languages")).All(ctx, db)
// Note that each level of a nested Load call will be loaded. No need to call Load() multiple times.

// Type safe queries exist for this too!
jets, _ := models.Jets(Load(Rels(models.JetRels.Pilot, models.PilotRels.Languages))).All(ctx, db)

// A larger example. In the below scenario, Pets will only be queried one time, despite
// showing up twice because they're the same query (the user's pets)
users, _ := models.Users(
  Load("Pets.Vets"),
  // the query mods passed in below only affect the query for Toys
  // to use query mods against Pets itself, you must declare it separately
  Load("Pets.Toys", Where("toys.deleted = ?", isDeleted)),
  Load("Property"),
  Where("age > ?", 23),
).All(ctx, db)
```

We provide the following methods for managing relationships on objects:

**To One**
- `SetX()`: Set the foreign key to point to something else: jet.SetPilot(...)
- `RemoveX()`: Null out the foreign key, effectively removing the relationship between these two objects: jet.RemovePilot(...)

**To Many**
- `AddX()`: Add more relationships to the existing set of related Xs: pilot.AddLanguages(...)
- `SetX()`: Remove all existing relationships, and replace them with the provided set: pilot.SetLanguages(...)
- `RemoveX()`: Remove all provided relationships: pilot.RemoveLanguages(...)

**Important**: Remember to use transactions around these set helpers for performance
and data integrity. SQLBoiler does not do this automatically due to it's transparent API which allows
you to batch any number of calls in a transaction without spawning subtransactions you don't know
about or are not supported by your database.

**To One** code examples:

```go
  jet, _ := models.FindJet(ctx, db, 1)
  pilot, _ := models.FindPilot(ctx, db, 1)

  // Set the pilot to an existing jet
  err := jet.SetPilot(ctx, db, false, &pilot)

  pilot = models.Pilot{
    Name: "Erlich",
  }

  // Insert the pilot into the database and assign it to a jet
  err := jet.SetPilot(ctx, db, true, &pilot)

  // Remove a relationship. This method only exists for foreign keys that can be NULL.
  err := jet.RemovePilot(ctx, db, &pilot)
```

**To Many** code examples:

```go
  pilots, _ := models.Pilots().All(ctx, db)
  languages, _ := models.Languages().All(ctx, db)

  // Set a group of language relationships
  err := pilots.SetLanguages(db, false, &languages)

  languages := []*models.Language{
    {Language: "Strayan"},
    {Language: "Yupik"},
    {Language: "Pawnee"},
  }

  // Insert new a group of languages and assign them to a pilot
  err := pilots.SetLanguages(ctx, db, true, languages...)

  // Add another language relationship to the existing set of relationships
  err := pilots.AddLanguages(ctx, db, false, &someOtherLanguage)

  anotherLanguage := models.Language{Language: "Archi"}

  // Insert and then add another language relationship
  err := pilots.AddLanguages(ctx, db, true, &anotherLanguage)

  // Remove a group of relationships
  err := pilots.RemoveLanguages(ctx, db, languages...)
```

### Hooks

Before and After hooks are available for most operations. If you don't need them you can
shrink the size of the generated code by disabling them with the `--no-hooks` flag.

Every generated package that includes hooks has the following `HookPoints` defined:

```go
const (
  BeforeInsertHook HookPoint = iota + 1
  BeforeUpdateHook
  BeforeDeleteHook
  BeforeUpsertHook
  AfterInsertHook
  AfterSelectHook
  AfterUpdateHook
  AfterDeleteHook
  AfterUpsertHook
)
```

To register a hook for your model you will need to create the hook function, and attach
it with the `AddModelHook` method. Here is an example of a before insert hook:

```go
// Define my hook function
func myHook(ctx context.Context, exec boil.ContextExecutor, p *Pilot) error {
  // Do stuff
  return nil
}

// Register my before insert hook for pilots
models.AddPilotHook(boil.BeforeInsertHook, myHook)
```

Your `ModelHook` will always be defined as `func(context.Context, boil.ContextExecutor, *Model) error` if context is not turned off.

#### Skipping Hooks

You can skip hooks by using the `boil.SkipHooks` on the context you pass in
to a given query.

### Transactions

The `boil.Executor` and `boil.ContextExecutor` interface powers all of SQLBoiler. This means
anything that conforms to the three `Exec/Query/QueryRow` methods (and their context-aware variants)
can be used to execute queries. `sql.DB`, `sql.Tx` as well as other
libraries (`sqlx`) conform to this interface, and therefore any of these things may be
used as an executor for any query in the system. This makes using transactions very simple:

```go
tx, err := db.BeginTx(ctx, nil)
if err != nil {
  return err
}

users, _ := models.Pilots().All(ctx, tx)
users.DeleteAll(ctx, tx)

// Rollback or commit
tx.Commit()
tx.Rollback()
```

It's also worth noting that there's a way to take advantage of `boil.SetDB()`
by using the
[boil.BeginTx()](https://pkg.go.dev/github.com/volatiletech/sqlboiler/v4/boil#BeginTx)
function. This opens a transaction using the globally stored database.

### Debug Logging

Debug logging will print your generated SQL statement and the arguments it is using.
Debug logging can be toggled on globally by setting the following global variable to `true`:

```go
boil.DebugMode = true

// Optionally set the writer as well. Defaults to os.Stdout
fh, _ := os.Open("debug.txt")
boil.DebugWriter = fh
```

Note: Debug output is messy at the moment. This is something we would like addressed.

### Select

Select is done through [Query Building](#query-building) and [Find](#find). Here's a short example:

```go
// Select one pilot
pilot, err := models.Pilots(qm.Where("name=?", "Tim")).One(ctx, db)
// Type safe variant
pilot, err := models.Pilots(models.PilotWhere.Name.EQ("Tim")).One(ctx, db)

// Select specific columns of many jets
jets, err := models.Jets(qm.Select("age", "name")).All(ctx, db)
// Type safe variant
jets, err := models.Jets(qm.Select(models.JetColumns.Age, models.JetColumns.Name)).All(ctx, db)
```

### Find

Find is used to find a single row by primary key:

```go
// Retrieve pilot with all columns filled
pilot, err := models.FindPilot(ctx, db, 1)

// Retrieve a subset of column values
jet, err := models.FindJet(ctx, db, 1, "name", "color")
```

### Insert

The main thing to be aware of with `Insert` is how the `columns` argument
operates. You can supply one of the following column lists:
`boil.Infer`, `boil.Whitelist`, `boil.Blacklist`, or `boil.Greylist`.

These lists control what fields are inserted into the database, and what values
are returned to your struct from the database (default, auto incrementing,
trigger-based columns are candidates for this). Your struct will have those
values after the insert is complete.

When you use inference `sqlboiler` looks at your Go struct field values and if
the field value is the Go zero value and that field has a default value in the
database it will not insert that field, instead it will get the value from the
database. Keep in mind `sqlboiler` cannot read or understand your default
values set in the database, so the Go zero value is what's important here (this
can be especially troubling for default true bool fields). Use a whitelist or
greylist in cases where you want to insert a Go zero value.

| Column List | Behavior |
| ----------- | -------- |
| Infer       | Infer the column list using "smart" rules
| Whitelist   | Insert only the columns specified in this list
| Blacklist   | Infer the column list, but ensure these columns are not inserted
| Greylist    | Infer the column list, but ensure these columns are inserted

**NOTE:** CreatedAt/UpdatedAt are not included in `Whitelist` automatically.

See the documentation for
[boil.Columns.InsertColumnSet](https://pkg.go.dev/github.com/volatiletech/sqlboiler/v4/boil/#Columns.InsertColumnSet)
for more details.

```go
var p1 models.Pilot
p1.Name = "Larry"
err := p1.Insert(ctx, db, boil.Infer()) // Insert the first pilot with name "Larry"
// p1 now has an ID field set to 1

var p2 models.Pilot
p2.Name = "Boris"
err := p2.Insert(ctx, db, boil.Infer()) // Insert the second pilot with name "Boris"
// p2 now has an ID field set to 2

var p3 models.Pilot
p3.ID = 25
p3.Name = "Rupert"
err := p3.Insert(ctx, db, boil.Infer()) // Insert the third pilot with a specific ID
// The id for this row was inserted as 25 in the database.

var p4 models.Pilot
p4.ID = 0
p4.Name = "Nigel"
err := p4.Insert(ctx, db, boil.Whitelist("id", "name")) // Insert the fourth pilot with a zero value ID
// The id for this row was inserted as 0 in the database.
// Note: We had to use the whitelist for this, otherwise
// SQLBoiler would presume you wanted to auto-increment
```

### Update
`Update` can be performed on a single object, a slice of objects or as a [Finisher](#finishers)
for a collection of rows.

`Update` on a single object optionally takes a `whitelist`. The purpose of the
whitelist is to specify which columns in your object should be updated in the database.

Like `Insert`, this method also takes a `Columns` type, but the behavior is
slightly different. Although the descriptions below look similar the full
documentation reveals the differences. Note that all inference is based on
the Go types zero value and not the database default value, read the `Insert`
documentation above for more details.

| Column List | Behavior |
| ----------- | -------- |
| Infer       | Infer the column list using "smart" rules
| Whitelist   | Update only the columns specified in this list
| Blacklist   | Infer the column list for updating, but ensure these columns are not updated
| Greylist    | Infer the column list, but ensure these columns are updated

**NOTE:** CreatedAt/UpdatedAt are not included in `Whitelist` automatically.

See the documentation for
[boil.Columns.UpdateColumnSet](https://pkg.go.dev/github.com/volatiletech/sqlboiler/v4/boil/#Columns.UpdateColumnSet)
for more details.

```go
// Find a pilot and update his name
pilot, _ := models.FindPilot(ctx, db, 1)
pilot.Name = "Neo"
rowsAff, err := pilot.Update(ctx, db, boil.Infer())

// Update a slice of pilots to have the name "Smith"
pilots, _ := models.Pilots().All(ctx, db)
rowsAff, err := pilots.UpdateAll(ctx, db, models.M{"name": "Smith"})

// Update all pilots in the database to to have the name "Smith"
rowsAff, err := models.Pilots().UpdateAll(ctx, db, models.M{"name": "Smith"})
```

### Delete

Delete a single object, a slice of objects or specific objects through [Query Building](#query-building).

```go
pilot, _ := models.FindPilot(db, 1)
// Delete the pilot from the database
rowsAff, err := pilot.Delete(ctx, db)

// Delete all pilots from the database
rowsAff, err := models.Pilots().DeleteAll(ctx, db)

// Delete a slice of pilots from the database
pilots, _ := models.Pilots().All(ctx, db)
rowsAff, err := pilots.DeleteAll(ctx, db)
```

### Upsert

[Upsert](https://www.postgresql.org/docs/9.5/static/sql-insert.html) allows you to perform an insert
that optionally performs an update when a conflict is found against existing row values.

The `updateColumns` and `insertColumns` operates in the same fashion that it does for [Update](#update)
and [Insert](#insert).


If an insert is performed, your object will be updated with any missing default values from the database,
such as auto-incrementing column values.

```go
var p1 models.Pilot
p1.ID = 5
p1.Name = "Gaben"

// INSERT INTO pilots ("id", "name") VALUES($1, $2)
// ON CONFLICT DO NOTHING
err := p1.Upsert(ctx, db, false, nil, boil.Infer())

// INSERT INTO pilots ("id", "name") VALUES ($1, $2)
// ON CONFLICT ("id") DO UPDATE SET "name" = EXCLUDED."name"
err := p1.Upsert(ctx, db, true, []string{"id"}, boil.Whitelist("name"), boil.Infer())

// Set p1.ID to a zero value. We will have to use the whitelist now.
p1.ID = 0
p1.Name = "Hogan"

// INSERT INTO pilots ("id", "name") VALUES ($1, $2)
// ON CONFLICT ("id") DO UPDATE SET "name" = EXCLUDED."name"
err := p1.Upsert(ctx, db, true, []string{"id"}, boil.Whitelist("name"), boil.Whitelist("id", "name"))
```

* **Postgres**
  * The `updateOnConflict` argument allows you to specify whether you would like Postgres
  to perform a `DO NOTHING` on conflict, opposed to a `DO UPDATE`. For MySQL and MSSQL, this param will not be generated.
  * The `conflictColumns` argument allows you to specify the `ON CONFLICT` columns for Postgres.
  For MySQL and MSSQL, this param will not be generated.
* **MySQL and MSSQL**
  * Passing `boil.None()` for `updateColumns` allows to perform a `DO NOTHING` on conflict similar to Postgres.

Note: Passing a different set of column values to the update component is not currently supported.

Note: Upsert is now not guaranteed to be provided by SQLBoiler and it's now up to each driver
individually to support it since it's a bit outside of the reach of the sql standard.

### Reload
In the event that your objects get out of sync with the database for whatever reason,
you can use `Reload` and `ReloadAll` to reload the objects using the primary key values
attached to the objects.

```go
pilot, _ := models.FindPilot(ctx, db, 1)

// > Object becomes out of sync for some reason, perhaps async processing

// Refresh the object with the latest data from the db
err := pilot.Reload(ctx, db)

// Reload all objects in a slice
pilots, _ := models.Pilots().All(ctx, db)
err := pilots.ReloadAll(ctx, db)
```

Note: `Reload` and `ReloadAll` are not recursive, if you need your relationships reloaded
you will need to call the `Reload` methods on those yourself.

### Exists

```go
jet, err := models.FindJet(ctx, db, 1)

// Check if the pilot assigned to this jet exists.
exists, err := jet.Pilot().Exists(ctx, db)

// Check if the pilot with ID 5 exists
exists, err := models.Pilots(Where("id=?", 5)).Exists(ctx, db)
```

### Enums

If your MySQL or Postgres tables use enums we will generate constants that hold their values
that you can use in your queries. For example:

```sql
CREATE TYPE workday AS ENUM('monday', 'tuesday', 'wednesday', 'thursday', 'friday');

CREATE TABLE event_one (
  id     serial PRIMARY KEY NOT NULL,
  name   VARCHAR(255),
  day    workday NOT NULL
);
```

An enum type defined like the above, being used by a table, will generate the following enums:

```go
const (
  WorkdayMonday    = "monday"
  WorkdayTuesday   = "tuesday"
  WorkdayWednesday = "wednesday"
  WorkdayThursday  = "thursday"
  WorkdayFriday    = "friday"
)
```

For Postgres we use `enum type name + title cased` value to generate the const variable name.
For MySQL we use `table name + column name + title cased value` to generate the const variable name.

Note: If your enum holds a value we cannot parse correctly due, to non-alphabet characters for example,
it may not be generated. In this event, you will receive errors in your generated tests because
the value randomizer in the test suite does not know how to generate valid enum values. You will
still be able to use your generated library, and it will still work as expected, but the only way
to get the tests to pass in this event is to either use a parsable enum value or use a regular column
instead of an enum.

### Constants

The models package will also contain some structs that contain all table,
column, relationship names harvested from the database at generation time. Type
safe where query mods are also generated.

There are type safe identifiers at:
* models.TableNames.TableName
* models.ModelColumns.ColumnName
* models.ModelWhere.ColumnName.Operator
* models.ModelRels.ForeignTableName

For table names they're generated under `models.TableNames`:

```go
// Generated code from models package
var TableNames = struct {
  Messages  string
  Purchases string
}{
  Messages:  "messages",
  Purchases: "purchases",
}

// Usage example:
fmt.Println(models.TableNames.Messages)
```

For column names they're generated under `models.{Model}Columns`:
```go
// Generated code from models package
var MessageColumns = struct {
  ID         string
  PurchaseID string
}{
  ID:         "id",
  PurchaseID: "purchase_id",
}

// Usage example:
fmt.Println(models.MessageColumns.ID)
```

For where clauses they're generated under `models.{Model}Where.{Column}.{Operator}`:
```go
var MessageWhere = struct {
  ID       whereHelperint
  Text     whereHelperstring
}{
  ID:         whereHelperint{field: `id`},
  PurchaseID: whereHelperstring{field: `purchase_id`},
}

// Usage example:
models.Messages(models.MessageWhere.PurchaseID.EQ("hello"))
```

For eager loading relationships ther're generated under `models.{Model}Rels`:
```go
// Generated code from models package
var MessageRels = struct {
  Purchase string
}{
  Purchase: "Purchase",
}

// Usage example:
fmt.Println(models.MessageRels.Purchase)
```

**NOTE:** You can also assign the ModelWhere or ColumnNames to a variable and
although you probably pay some performance penalty with it sometimes the
readability increase is worth it:

```go
cols := &models.UserColumns
where := &models.UserWhere

u, err := models.Users(where.Name.EQ("hello"), qm.Or(cols.Age + "=?", 5))
```

## FAQ

#### Won't compiling models for a huge database be very slow?

No, because Go's toolchain - unlike traditional toolchains - makes the compiler do most of the work
instead of the linker. This means that when the first `go install` is done it can take
a little bit of time because there is a lot of code that is generated. However, because of this
work balance between the compiler and linker in Go, linking to that code afterwards in the subsequent
compiles is extremely fast.

#### Missing imports for generated package

The generated models might import a couple of packages that are not on your system already, so
`cd` into your generated models directory and type `go get -u -t` to fetch them. You will only need
to run this command once, not per generation.

#### How should I handle multiple schemas?

If your database uses multiple schemas you should generate a new package for each of your schemas.
Note that this only applies to databases that use real, SQL standard schemas (like PostgreSQL), not
fake schemas (like MySQL).

#### How do I use types.BytesArray for Postgres bytea arrays?

Only "escaped format" is supported for types.BytesArray. This means that your byte slice needs to have
a format of "\\x00" (4 bytes per byte) opposed to "\x00" (1 byte per byte). This is to maintain compatibility
with all Postgres drivers. Example:

`x := types.BytesArray{0: []byte("\\x68\\x69")}`

Please note that multi-dimensional Postgres ARRAY types are not supported at this time.

#### Why aren't my time.Time or null.Time fields working in MySQL?

You *must* use a DSN flag in MySQL connections, see: [Requirements](#requirements)

#### Where is the homepage?

The homepage for the [SQLBoiler](https://github.com/volatiletech/sqlboiler) [Golang ORM](https://github.com/volatiletech/sqlboiler)
generator is located at: https://github.com/volatiletech/sqlboiler

#### Why are the auto-generated tests failing?

The tests generated for your models package with sqlboiler are fairly
error-prone. They are usually broken by constraints in the database
that sqlboiler can't hope to understand.

During regular run-time this isn't an issue because your code will throw errors
and you will fix it however the auto-generated tests can only report those
errors and it seems like something is wrong when in reality the only issue is
that the auto generated tests can't understand that your `text` column is
validated by a regex that says it must be composed solely of the 'b' character
repeated 342 times.

These tests are broken especially by foreign key constraints because of the
parallelism we use. There's also no understanding in the tests of dependencies
based on these foreign keys. As such there is a process that removes the foreign
keys from your schema when they are run, if this process messes up you will get
errors relating to foreign key constraints.

## Benchmarks

If you'd like to run the benchmarks yourself check out our [boilbench](https://github.com/volatiletech/boilbench) repo.

```bash
go test -bench . -benchmem
```

### Results (lower is better)

Test machine:
```text
OS:  Ubuntu 16.04
CPU: Intel(R) Core(TM) i7-4771 CPU @ 3.50GHz
Mem: 16GB
Go:  go version go1.8.1 linux/amd64
```

The graphs below have many runs like this as input to calculate errors. Here
is a sample run:

```text
BenchmarkGORMSelectAll/gorm-8         20000   66500 ns/op   28998 B/op    455 allocs/op
BenchmarkGORPSelectAll/gorp-8         50000   31305 ns/op    9141 B/op    318 allocs/op
BenchmarkXORMSelectAll/xorm-8         20000   66074 ns/op   16317 B/op    417 allocs/op
BenchmarkKallaxSelectAll/kallax-8    100000   18278 ns/op    7428 B/op    145 allocs/op
BenchmarkBoilSelectAll/boil-8        100000   12759 ns/op    3145 B/op     67 allocs/op

BenchmarkGORMSelectSubset/gorm-8      20000    69469 ns/op   30008 B/op   462 allocs/op
BenchmarkGORPSelectSubset/gorp-8      50000    31102 ns/op    9141 B/op   318 allocs/op
BenchmarkXORMSelectSubset/xorm-8      20000    64151 ns/op   15933 B/op   414 allocs/op
BenchmarkKallaxSelectSubset/kallax-8 100000    16996 ns/op    6499 B/op   132 allocs/op
BenchmarkBoilSelectSubset/boil-8     100000    13579 ns/op    3281 B/op    71 allocs/op

BenchmarkGORMSelectComplex/gorm-8     20000    76284 ns/op   34566 B/op   521 allocs/op
BenchmarkGORPSelectComplex/gorp-8     50000    31886 ns/op    9501 B/op   328 allocs/op
BenchmarkXORMSelectComplex/xorm-8     20000    68430 ns/op   17694 B/op   464 allocs/op
BenchmarkKallaxSelectComplex/kallax-8 50000    26095 ns/op   10293 B/op   212 allocs/op
BenchmarkBoilSelectComplex/boil-8    100000    16403 ns/op    4205 B/op   102 allocs/op

BenchmarkGORMDelete/gorm-8           200000    10356 ns/op    5059 B/op    98 allocs/op
BenchmarkGORPDelete/gorp-8          1000000     1335 ns/op     352 B/op    13 allocs/op
BenchmarkXORMDelete/xorm-8           200000    10796 ns/op    4146 B/op   122 allocs/op
BenchmarkKallaxDelete/kallax-8       300000     5141 ns/op    2241 B/op    48 allocs/op
BenchmarkBoilDelete/boil-8          2000000      796 ns/op     168 B/op     8 allocs/op

BenchmarkGORMInsert/gorm-8           100000    15238 ns/op    8278 B/op   150 allocs/op
BenchmarkGORPInsert/gorp-8           300000     4648 ns/op    1616 B/op    38 allocs/op
BenchmarkXORMInsert/xorm-8           100000    12600 ns/op    6092 B/op   138 allocs/op
BenchmarkKallaxInsert/kallax-8       100000    15115 ns/op    6003 B/op   126 allocs/op
BenchmarkBoilInsert/boil-8          1000000     2249 ns/op     984 B/op    23 allocs/op

BenchmarkGORMUpdate/gorm-8           100000    18609 ns/op    9389 B/op   174 allocs/op
BenchmarkGORPUpdate/gorp-8           500000     3180 ns/op    1536 B/op    35 allocs/op
BenchmarkXORMUpdate/xorm-8           100000    13149 ns/op    5098 B/op   149 allocs/op
BenchmarkKallaxUpdate/kallax-8       100000    22880 ns/op   11366 B/op   219 allocs/op
BenchmarkBoilUpdate/boil-8          1000000     1810 ns/op     936 B/op    18 allocs/op

BenchmarkGORMRawBind/gorm-8           20000    65821 ns/op   30502 B/op   444 allocs/op
BenchmarkGORPRawBind/gorp-8           50000    31300 ns/op    9141 B/op   318 allocs/op
BenchmarkXORMRawBind/xorm-8           20000    62024 ns/op   15588 B/op   403 allocs/op
BenchmarkKallaxRawBind/kallax-8      200000     7843 ns/op    4380 B/op    46 allocs/op
BenchmarkSQLXRawBind/sqlx-8          100000    13056 ns/op    4572 B/op    55 allocs/op
BenchmarkBoilRawBind/boil-8          200000    11519 ns/op    4638 B/op    55 allocs/op
```

<img src="http://i.imgur.com/SltE8UQ.png"/><img src="http://i.imgur.com/lzvM5jJ.png"/><img src="http://i.imgur.com/SS0zNd2.png"/>

<img src="http://i.imgur.com/Kk0IM0J.png"/><img src="http://i.imgur.com/1IFtpdP.png"/><img src="http://i.imgur.com/t6Usecx.png"/>

<img src="http://i.imgur.com/98DOzcr.png"/><img src="http://i.imgur.com/NSp5r4Q.png"/><img src="http://i.imgur.com/dEGlOgI.png"/>

<img src="http://i.imgur.com/W0zhuGb.png"/><img src="http://i.imgur.com/YIvDuFv.png"/><img src="http://i.imgur.com/sKwuMaU.png"/>

<img src="http://i.imgur.com/ZUMYVmw.png"/><img src="http://i.imgur.com/T61rH3K.png"/><img src="http://i.imgur.com/lDr0xhY.png"/>

<img src="http://i.imgur.com/LWo10M9.png"/><img src="http://i.imgur.com/Td15owT.png"/><img src="http://i.imgur.com/45XXw4K.png"/>

<img src="http://i.imgur.com/lpP8qds.png"/><img src="http://i.imgur.com/hLyH3jQ.png"/><img src="http://i.imgur.com/C2v10t3.png"/>