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
OpenTracingstandard - 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
- subscriptions
Roadmap
We're trying out the GitHub Project feature to manage graphql-go's development roadmap.
Feedback is welcome and appreciated.
(Some) Documentation
Basic Sample
package main
import (
"log"
"net/http"
graphql "github.com/golangid/graphql-go"
"github.com/golangid/graphql-go/relay"
)
type query struct{}
func (_ *query) Hello() string { return "Hello, world!" }
func main() {
s := `
type Query {
hello: String!
}
`
schema := graphql.MustParseSchema(s, &query{})
http.Handle("/query", &relay.Handler{Schema: schema})
log.Fatal(http.ListenAndServe(":8080", nil))
}
To test:
$ curl -XPOST -d '{"query": "{ hello }"}' localhost:8080/query
Resolvers
A resolver must have one method or field for each field of the GraphQL type it resolves. The method or field name has to be exported and match the schema's field's name in a non-case-sensitive way.
You can use struct fields as resolvers by using SchemaOpt: UseFieldResolvers(). For example,
opts := []graphql.SchemaOpt{graphql.UseFieldResolvers()}
schema := graphql.MustParseSchema(s, &query{}, opts...)
When using UseFieldResolvers schema option, a struct field will be used only when:
- there is no method for a struct field
- a struct field does not implement an interface method
- a struct field does not have arguments
The method has up to two arguments:
- Optional
context.Contextargument. - 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
errorresult.
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
}
Schema Options
UseStringDescriptions()enables the usage of double quoted and triple quoted. When this is not enabled, comments are parsed as descriptions instead.UseFieldResolvers()specifies whether to use struct field resolvers.MaxDepth(n int)specifies the maximum field nesting depth in a query. The default is 0 which disables max depth checking.MaxParallelism(n int)specifies the maximum number of resolvers per request allowed to run in parallel. The default is 10.Tracer(tracer trace.Tracer)is used to trace queries and fields. It defaults totrace.OpenTracingTracer.ValidationTracer(tracer trace.ValidationTracer)is used to trace validation errors. It defaults totrace.NoopValidationTracer.Logger(logger log.Logger)is used to log panics during query execution. It defaults toexec.DefaultLogger.DisableIntrospection()disables introspection queries.
Custom Errors
Errors returned by resolvers can include custom extensions by implementing the ResolverError interface:
type ResolverError interface {
error
Extensions() map[string]interface{}
}
Example of a simple custom error:
type droidNotFoundError struct {
Code string `json:"code"`
Message string `json:"message"`
}
func (e droidNotFoundError) Error() string {
return fmt.Sprintf("error [%s]: %s", e.Code, e.Message)
}
func (e droidNotFoundError) Extensions() map[string]interface{} {
return map[string]interface{}{
"code": e.Code,
"message": e.Message,
}
}
Which could produce a GraphQL error such as:
{
"errors": [
{
"message": "error [NotFound]: This is not the droid you are looking for",
"path": [
"droid"
],
"extensions": {
"code": "NotFound",
"message": "This is not the droid you are looking for"
}
}
],
"data": null
}
Examples
Companies that use this library
Documentation
¶
Index ¶
- type ID
- type Response
- type Schema
- func (s *Schema) Exec(ctx context.Context, queryString string, operationName string, ...) *Response
- func (s *Schema) Inspect() *introspection.Schema
- func (s *Schema) Subscribe(ctx context.Context, queryString string, operationName string, ...) (<-chan interface{}, error)
- func (s *Schema) ToJSON() ([]byte, error)
- func (s *Schema) Validate(queryString string) []*errors.QueryError
- type SchemaOpt
- func DisableIntrospection() SchemaOpt
- func Logger(logger log.Logger) SchemaOpt
- func MaxDepth(n int) SchemaOpt
- func MaxParallelism(n int) SchemaOpt
- func Tracer(tracer trace.Tracer) SchemaOpt
- func UseFieldResolvers() SchemaOpt
- func UseStringDescriptions() SchemaOpt
- func ValidationTracer(tracer trace.ValidationTracer) SchemaOpt
- type Time
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
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) MarshalJSON ¶
func (*ID) UnmarshalGraphQL ¶
type Response ¶
type Response struct {
Errors []*errors.QueryError `json:"errors,omitempty"`
Data json.RawMessage `json:"data,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. Errors are intentionally serialized first based on the advice in https://github.com/facebook/graphql/commit/7b40390d48680b15cb93e02d46ac5eb249689876#diff-757cea6edf0288677a9eea4cfc801d87R107
type Schema ¶
type Schema struct {
// contains filtered or unexported fields
}
Schema represents a GraphQL schema with an optional resolver.
func MustParseSchema ¶
MustParseSchema calls ParseSchema and panics on error.
func ParseSchema ¶
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) Subscribe ¶
func (s *Schema) Subscribe(ctx context.Context, queryString string, operationName string, variables map[string]interface{}) (<-chan interface{}, error)
Subscribe returns a response channel for the given subscription with the schema's resolver. It returns an error if the schema was created without a resolver. If the context gets cancelled, the response channel will be closed and no further resolvers will be called. The context error will be returned as soon as possible (not immediately).
type SchemaOpt ¶
type SchemaOpt func(*Schema)
SchemaOpt is an option to pass to ParseSchema or MustParseSchema.
func DisableIntrospection ¶
func DisableIntrospection() SchemaOpt
DisableIntrospection disables introspection queries.
func Logger ¶
Logger is used to log panics during query execution. It defaults to exec.DefaultLogger.
func MaxDepth ¶
MaxDepth specifies the maximum field nesting depth in a query. The default is 0 which disables max depth checking.
func MaxParallelism ¶
MaxParallelism specifies the maximum number of resolvers per request allowed to run in parallel. The default is 10.
func UseFieldResolvers ¶
func UseFieldResolvers() SchemaOpt
UseFieldResolvers specifies whether to use struct field resolvers
func UseStringDescriptions ¶
func UseStringDescriptions() SchemaOpt
UseStringDescriptions enables the usage of double quoted and triple quoted strings as descriptions as per the June 2018 spec https://facebook.github.io/graphql/June2018/. When this is not enabled, comments are parsed as descriptions instead.
func ValidationTracer ¶
func ValidationTracer(tracer trace.ValidationTracer) SchemaOpt
ValidationTracer is used to trace validation errors. It defaults to trace.NoopValidationTracer.
type 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 ¶
ImplementsGraphQLType maps this custom Go type to the graphql scalar type in the schema.
func (Time) MarshalJSON ¶
MarshalJSON is a custom marshaler for Time
This function will be called whenever you query for fields that use the Time type
func (*Time) UnmarshalGraphQL ¶
UnmarshalGraphQL is a custom unmarshaler for Time
This function will be called whenever you use the time scalar as an input
Source Files
Directories
¶
| Path | Synopsis |
|---|---|
|
example
|
|
|
caching/cache
Package cache implements caching of GraphQL requests by allowing resolvers to provide hints about their cacheability, which can be used by the transport handlers (e.g.
|
Package cache implements caching of GraphQL requests by allowing resolvers to provide hints about their cacheability, which can be used by the transport handlers (e.g. |
|
starwars
Package starwars provides a example schema and resolver based on Star Wars characters.
|
Package starwars provides a example schema and resolver based on Star Wars characters. |
|
internal
|
|