github.com/Desuuuu/genqlient@v0.5.3/README.md (about) 1 <img width="100%" alt="generated graphql client ⇒ genqlient" src="docs/images/genqlient.svg"> 2 3 [](https://pkg.go.dev/github.com/Desuuuu/genqlient) 4 [](https://github.com/Desuuuu/genqlient/actions) 5 [](docs/CODE_OF_CONDUCT.md) 6 [](https://goreportcard.com/report/github.com/Desuuuu/genqlient) 7 8 # genqlient: a truly type-safe Go GraphQL client 9 10 ## What is genqlient? 11 12 genqlient is a Go library to easily generate type-safe code to query a GraphQL API. It takes advantage of the fact that both GraphQL and Go are typed languages to ensure at compile-time that your code is making a valid GraphQL query and using the result correctly, all with a minimum of boilerplate. 13 14 genqlient provides: 15 16 - Compile-time validation of GraphQL queries: never ship an invalid GraphQL query again! 17 - Type-safe response objects: genqlient generates the right type for each query, so you know the response will unmarshal correctly and never need to use `interface{}`. 18 - Production-readiness: genqlient is used in production at Khan Academy, where it supports millions of learners and teachers around the world. 19 20 ## How do I use genqlient? 21 22 You can download and run genqlient the usual way: `go run github.com/Desuuuu/genqlient`. To set your project up to use genqlient, see the [getting started guide](docs/INTRODUCTION.md), or the [example](example). For more complete documentation, see the [docs](docs). 23 24 ## How can I help? 25 26 genqlient welcomes contributions! Check out the ([Contribution Guidelines](docs/CONTRIBUTING.md)), or file an issue [on GitHub](issues). 27 28 ## Why another GraphQL client? 29 30 Most common Go GraphQL clients have you write code something like this: 31 ```go 32 query := `query GetUser($id: ID!) { user(id: $id) { name } }` 33 variables := map[string]interface{}{"id": "123"} 34 var resp struct { 35 Me struct { 36 Name graphql.String 37 } 38 } 39 client.Query(ctx, query, &resp, variables) 40 fmt.Println(query.Me.Name) 41 // Output: Luke Skywalker 42 ``` 43 44 This code works, but it has a few problems: 45 46 - While the response struct is type-safe at the Go level; there's nothing to check that the schema looks like you expect. Maybe the field is called `fullName`, not `name`; or maybe you capitalized it wrong (since Go and GraphQL have different conventions); you won't know until runtime. 47 - The GraphQL variables aren't type-safe at all; you could have passed `{"id": true}` and again you won't know until runtime! 48 - You have to write everything twice, or hide the query in complicated struct tags, or give up what type safety you do have and resort to `interface{}`. 49 50 These problems aren't a big deal in a small application, but for serious production-grade tools they're not ideal. And they should be entirely avoidable: GraphQL and Go are both typed languages; and GraphQL servers expose their schema in a standard, machine-readable format. We should be able to simply write a query and have that automatically validated against the schema and turned into a Go struct which we can use in our code. In fact, there's already good prior art to do this sort of thing: [99designs/gqlgen](https://github.com/99designs/gqlgen) is a popular server library that generates types, and Apollo has a [codegen tool](https://www.apollographql.com/docs/devtools/cli/#supported-commands) to generate similar client-types for several other languages. (See [docs/DESIGN.md](docs/DESIGN.md) for more prior art.) 51 52 genqlient fills that gap: you just specify the query, and it generates type-safe helpers, validated against the schema, that make the query.