Ben Kraft
f7c81e9997
## Summary: I'm not going to really publicize it until the blog post is done, but with all the usual boilerplate set up, it's time to remove this note! (Actually, I meant to do it in #96, but forgot.) ## Test plan: read it Author: benjaminjkraft Reviewers: dnerdy, dangoor, StevenACoffman Required Reviewers: Approved By: dnerdy, dangoor Checks: ✅ Test (1.17), ✅ Test (1.16), ✅ Test (1.15), ✅ Test (1.14), ✅ Lint, ✅ Test (1.17), ✅ Test (1.16), ✅ Test (1.15), ✅ Test (1.14), ✅ Lint Pull Request URL: https://github.com/Khan/genqlient/pull/102
53 lines
3.7 KiB
Markdown
53 lines
3.7 KiB
Markdown
<img width="100%" alt="generated graphql client ⇒ genqlient" src="docs/images/genqlient.svg">
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[](https://pkg.go.dev/github.com/Khan/genqlient)
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[](https://github.com/Khan/genqlient/actions)
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[](docs/CODE_OF_CONDUCT.md)
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[](https://goreportcard.com/report/github.com/Khan/genqlient)
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# genqlient: a truly type-safe Go GraphQL client
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## What is genqlient?
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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.
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genqlient provides:
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- Compile-time validation of GraphQL queries: never ship an invalid GraphQL query again!
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- 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{}`.
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- Production-readiness: genqlient is used in production at Khan Academy, where it supports millions of learners and teachers around the world.
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## How do I use genqlient?
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You can download and run genqlient the usual way: `go run github.com/Khan/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).
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## How can I help?
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genqlient welcomes contributions! Check out the ([Contribution Guidelines](docs/CONTRIBUTING.md)), or file an issue [on GitHub](issues).
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## Why another GraphQL client?
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Most common Go GraphQL clients have you write code something like this:
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```go
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query := `query GetUser($id: ID!) { user(id: $id) { name } }`
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variables := map[string]interface{}{"id": "123"}
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var resp struct {
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Me struct {
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Name graphql.String
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}
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}
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client.Query(ctx, query, &resp, variables)
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fmt.Println(query.Me.Name)
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// Output: Luke Skywalker
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```
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This code works, but it has a few problems:
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- 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.
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- The GraphQL variables aren't type-safe at all; you could have passed `{"id": true}` and again you won't know until runtime!
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- 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{}`.
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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.)
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genqlient fills that gap: you just specify the query, and it generates type-safe helpers, validated against the schema, that make the query.
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