/graphql-go

GraphQL server with a focus on ease of use

Primary LanguageGoBSD 2-Clause "Simplified" LicenseBSD-2-Clause

graphql-go

Sourcegraph Build Status GoDoc

Status

The project is under heavy development. It is stable enough so we use it in production at Sourcegraph, but expect changes.

Goals

  • full support of GraphQL spec (October 2016)
    • propagation of null on resolver errors
    • everything else
  • minimal API
  • support for context.Context and OpenTracing
  • early error detection at application startup by type-checking if the given resolver matches the schema
  • resolvers are purely based on method sets (e.g. it's up to you if you want to resolve a GraphQL interface with a Go interface or a Go struct)
  • nice error messages (no internal panics, even with an invalid schema or resolver; please file a bug if you see an internal panic)
    • nice errors on resolver validation
    • nice errors on all invalid schemas
    • nice errors on all invalid queries
  • panic handling (a panic in a resolver should not take down the whole app)
  • parallel execution of resolvers

(Some) Documentation

Resolvers

A resolver must have one method for each field of the GraphQL type it resolves. The method name has to be exported and match the field's name in a non-case-sensitive way.

The method has up to two arguments:

  • Optional context.Context argument.
  • Mandatory *struct { ... } argument if the corresponding GraphQL field has arguments. The names of the struct fields have to be exported and have to match the names of the GraphQL arguments in a non-case-sensitive way.

The method has up to two results:

  • The GraphQL field's value as determined by the resolver.
  • Optional error result.

Example for a simple resolver method:

func (r *helloWorldResolver) Hello() string {
	return "Hello world!"
}

The following signature is also allowed:

func (r *helloWorldResolver) Hello(ctx context.Context) (string, error) {
	return "Hello world!", nil
}