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https://github.com/khan/genqlient
a truly type-safe Go GraphQL client
https://github.com/khan/genqlient
codegen go golang graphql
Last synced: 23 days ago
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a truly type-safe Go GraphQL client
- Host: GitHub
- URL: https://github.com/khan/genqlient
- Owner: Khan
- License: mit
- Created: 2020-01-17T02:01:49.000Z (almost 5 years ago)
- Default Branch: main
- Last Pushed: 2024-09-30T15:57:59.000Z (about 1 month ago)
- Last Synced: 2024-10-15T14:41:06.500Z (23 days ago)
- Topics: codegen, go, golang, graphql
- Language: Go
- Homepage:
- Size: 1.3 MB
- Stars: 1,073
- Watchers: 52
- Forks: 107
- Open Issues: 58
-
Metadata Files:
- Readme: README.md
- Contributing: docs/CONTRIBUTING.md
- License: LICENSE
- Code of conduct: docs/CODE_OF_CONDUCT.md
- Codeowners: .github/CODEOWNERS
- Security: docs/SECURITY.md
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README
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# genqlient: a truly type-safe Go GraphQL client
## What is genqlient?
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.
genqlient provides:
- Compile-time validation of GraphQL queries: never ship an invalid GraphQL query again!
- 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{}`.
- Production-readiness: genqlient is used in production at Khan Academy, where it supports millions of learners and teachers around the world.
## How do I use genqlient?
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).
## How can I help?
genqlient welcomes contributions! Check out the ([Contribution Guidelines](docs/CONTRIBUTING.md)), or file an issue [on GitHub](issues).
## Why another GraphQL client?
Most common Go GraphQL clients have you write code something like this:
```go
query := `query GetUser($id: ID!) { user(id: $id) { name } }`
variables := map[string]interface{}{"id": "123"}
var resp struct {
Me struct {
Name graphql.String
}
}
client.Query(ctx, query, &resp, variables)
fmt.Println(resp.Me.Name)
// Output: Luke Skywalker
```
This code works, but it has a few problems:
- 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.
- The GraphQL variables aren't type-safe at all; you could have passed `{"id": true}` and again you won't know until runtime!
- 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{}`.
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 the [design note](docs/design.md) for more prior art.)
genqlient fills that gap: you just specify the query, and it generates type-safe helpers, validated against the schema, that make the query.