github.com/ecodeclub/eorm@v0.0.2-0.20231001112437-dae71da914d0/delete.go (about)

     1  // Copyright 2021 ecodeclub
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  // http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package eorm
    16  
    17  import (
    18  	"context"
    19  
    20  	"github.com/valyala/bytebufferpool"
    21  )
    22  
    23  var _ QueryBuilder = &Deleter[any]{}
    24  
    25  // Deleter builds DELETE query
    26  type Deleter[T any] struct {
    27  	builder
    28  	Session
    29  	table interface{}
    30  	where []Predicate
    31  }
    32  
    33  // NewDeleter 开始构建一个 DELETE 查询
    34  func NewDeleter[T any](sess Session) *Deleter[T] {
    35  	return &Deleter[T]{
    36  		builder: builder{
    37  			core:   sess.getCore(),
    38  			buffer: bytebufferpool.Get(),
    39  		},
    40  		Session: sess,
    41  	}
    42  }
    43  
    44  // Build returns DELETE query
    45  func (d *Deleter[T]) Build() (Query, error) {
    46  	defer bytebufferpool.Put(d.buffer)
    47  	_, _ = d.buffer.WriteString("DELETE FROM ")
    48  	var err error
    49  	if d.table == nil {
    50  		d.table = new(T)
    51  	}
    52  	d.meta, err = d.metaRegistry.Get(d.table)
    53  	if err != nil {
    54  		return EmptyQuery, err
    55  	}
    56  
    57  	d.quote(d.meta.TableName)
    58  	if len(d.where) > 0 {
    59  		d.writeString(" WHERE ")
    60  		err = d.buildPredicates(d.where)
    61  		if err != nil {
    62  			return EmptyQuery, err
    63  		}
    64  	}
    65  	d.end()
    66  	return Query{SQL: d.buffer.String(), Args: d.args}, nil
    67  }
    68  
    69  // From accepts model definition
    70  func (d *Deleter[T]) From(table interface{}) *Deleter[T] {
    71  	d.table = table
    72  	return d
    73  }
    74  
    75  // Where accepts predicates
    76  func (d *Deleter[T]) Where(predicates ...Predicate) *Deleter[T] {
    77  	d.where = predicates
    78  	return d
    79  }
    80  
    81  // Exec sql
    82  func (d *Deleter[T]) Exec(ctx context.Context) Result {
    83  	query, err := d.Build()
    84  	if err != nil {
    85  		return Result{err: err}
    86  	}
    87  	return newQuerier[T](d.Session, query, d.meta, DELETE).Exec(ctx)
    88  }