graphql

README

graphql-go

The goal of this project is to provide full support of the GraphQL draft specification with a set of idiomatic, easy to use Go packages.

While still under heavy development (internal APIs are almost certainly subject to change), this library is safe for production use.

Features

• minimal API
• support for context.Context
• support for the OpenTracing standard
• schema type-checking against resolvers
• resolvers are matched to the schema based on method sets (can resolve a GraphQL schema with a Go interface or Go struct).
• handles panics in resolvers
• parallel execution of resolvers

Roadmap

We're trying out the GitHub Project feature to manage graphql-go's development roadmap. Feedback is welcome and appreciated.

(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
}

Community Examples

tonyghita/graphql-go-example - A more "productionized" version of the Star Wars API example given in this repository.

deltaskelta/graphql-go-pets-example - graphql-go resolving against a sqlite database

OscarYuen/go-graphql-starter - a starter application integrated with dataloader, psql and basic authenication

Documentation

Index

• type ID
  • func (ID) ImplementsGraphQLType(name string) bool
  • func (id ID) MarshalJSON() ([]byte, error)
  • func (id *ID) UnmarshalGraphQL(input interface{}) error
• type Response
• type Schema
  • func MustParseSchema(schemaString string, resolver interface{}, opts ...SchemaOpt) *Schema
  • func ParseSchema(schemaString string, resolver interface{}, opts ...SchemaOpt) (*Schema, error)
  • func (s *Schema) Exec(ctx context.Context, queryString string, operationName string, ...) *Response
  • func (s *Schema) Inspect() *introspection.Schema
  • func (s *Schema) ToJSON() ([]byte, error)
  • func (s *Schema) Validate(queryString string) []*errors.QueryError
• type SchemaOpt
  • func Logger(logger log.Logger) SchemaOpt
  • func MaxDepth(n int) SchemaOpt
  • func MaxParallelism(n int) SchemaOpt
  • func Tracer(tracer trace.Tracer) SchemaOpt
  • func ValidationTracer(tracer trace.ValidationTracer) SchemaOpt
• type Time
  • func (Time) ImplementsGraphQLType(name string) bool
  • func (t *Time) UnmarshalGraphQL(input interface{}) error

Types

type ID

type ID string

ID represents GraphQL's "ID" scalar type. A custom type may be used instead.

func (ID) ImplementsGraphQLType

func (ID) ImplementsGraphQLType(name string) bool

func (ID) MarshalJSON

func (id ID) MarshalJSON() ([]byte, error)

func (*ID) UnmarshalGraphQL

func (id *ID) UnmarshalGraphQL(input interface{}) error

type Response

type Response struct {
	Data       json.RawMessage        `json:"data,omitempty"`
	Errors     []*errors.QueryError   `json:"errors,omitempty"`
	Extensions map[string]interface{} `json:"extensions,omitempty"`
}

Response represents a typical response of a GraphQL server. It may be encoded to JSON directly or it may be further processed to a custom response type, for example to include custom error data.

type Schema

type Schema struct {
	// contains filtered or unexported fields
}

Schema represents a GraphQL schema with an optional resolver.

func MustParseSchema

func MustParseSchema(schemaString string, resolver interface{}, opts ...SchemaOpt) *Schema

MustParseSchema calls ParseSchema and panics on error.

func ParseSchema

func ParseSchema(schemaString string, resolver interface{}, opts ...SchemaOpt) (*Schema, error)

ParseSchema parses a GraphQL schema and attaches the given root resolver. It returns an error if the Go type signature of the resolvers does not match the schema. If nil is passed as the resolver, then the schema can not be executed, but it may be inspected (e.g. with ToJSON).

func (*Schema) Exec

func (s *Schema) Exec(ctx context.Context, queryString string, operationName string, variables map[string]interface{}) *Response

Exec executes the given query with the schema's resolver. It panics if the schema was created without a resolver. If the context get cancelled, no further resolvers will be called and a the context error will be returned as soon as possible (not immediately).

func (*Schema) Inspect

func (s *Schema) Inspect() *introspection.Schema

Inspect allows inspection of the given schema.

func (*Schema) ToJSON

func (s *Schema) ToJSON() ([]byte, error)

ToJSON encodes the schema in a JSON format used by tools like Relay.

func (*Schema) Validate

func (s *Schema) Validate(queryString string) []*errors.QueryError

Validate validates the given query with the schema.

type SchemaOpt

type SchemaOpt func(*Schema)

SchemaOpt is an option to pass to ParseSchema or MustParseSchema.

func Logger

func Logger(logger log.Logger) SchemaOpt

Logger is used to log panics durring query execution. It defaults to exec.DefaultLogger.

func MaxDepth

func MaxDepth(n int) SchemaOpt

MaxDepth specifies the maximum field nesting depth in a query. The default is 0 which disables max depth checking.

func MaxParallelism

func MaxParallelism(n int) SchemaOpt

MaxParallelism specifies the maximum number of resolvers per request allowed to run in parallel. The default is 10.

func Tracer

func Tracer(tracer trace.Tracer) SchemaOpt

Tracer is used to trace queries and fields. It defaults to trace.OpenTracingTracer.

func ValidationTracer

func ValidationTracer(tracer trace.ValidationTracer) SchemaOpt

ValidationTracer is used to trace validation errors. It defaults to trace.NoopValidationTracer.

type Time

type Time struct {
	time.Time
}

Time is a custom GraphQL type to represent an instant in time. It has to be added to a schema via "scalar Time" since it is not a predeclared GraphQL type like "ID".

func (Time) ImplementsGraphQLType

func (Time) ImplementsGraphQLType(name string) bool

func (*Time) UnmarshalGraphQL

func (t *Time) UnmarshalGraphQL(input interface{}) error