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engine.go
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engine.go
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package graphql
import (
"context"
"encoding/json"
"reflect"
"github.com/chirino/graphql/internal/exec"
"github.com/chirino/graphql/internal/introspection"
"github.com/chirino/graphql/internal/validation"
"github.com/chirino/graphql/log"
"github.com/chirino/graphql/qerrors"
"github.com/chirino/graphql/resolvers"
"github.com/chirino/graphql/schema"
"github.com/chirino/graphql/trace"
)
type Engine struct {
Schema *schema.Schema
MaxDepth int
MaxParallelism int
Tracer trace.Tracer
Logger log.Logger
Resolver resolvers.Resolver
Root interface{}
// Validate can be set to nil to disable validation.
Validate func(doc *schema.QueryDocument, maxDepth int) error
// OnRequest is called after the query is parsed but before the request is validated.
OnRequestHook func(request *Request, doc *schema.QueryDocument, op *schema.Operation) error
TryCast func(value reflect.Value, toType string) (v reflect.Value, ok bool)
}
func CreateEngine(schema string) (*Engine, error) {
engine := New()
err := engine.Schema.Parse(schema)
return engine, err
}
func New() *Engine {
e := &Engine{
Schema: schema.New(),
Tracer: trace.NoopTracer{},
MaxParallelism: 10,
MaxDepth: 50,
Logger: &log.DefaultLogger{},
Resolver: resolvers.DynamicResolverFactory(),
TryCast: resolvers.TryCastFunction,
}
e.Validate = e.validate
return e
}
func (engine *Engine) GetSchemaIntrospectionJSON() ([]byte, error) {
return GetSchemaIntrospectionJSON(engine.ServeGraphQL)
}
func (engine *Engine) Exec(ctx context.Context, result interface{}, query string, args ...interface{}) error {
return Exec(engine.ServeGraphQL, ctx, result, query, args...)
}
func (engine *Engine) ServeGraphQL(request *Request) *Response {
return ServeGraphQLStreamFunc(engine.ServeGraphQLStream).ServeGraphQL(request)
}
type responseStream struct {
cancel context.CancelFunc
responses chan *Response
}
func (r responseStream) Close() {
r.cancel()
}
func (r responseStream) Responses() <-chan *Response {
return r.responses
}
func (r responseStream) CloseWithErr(err error) responseStream {
r.responses <- NewResponse().AddError(err)
close(r.responses)
return r
}
func (engine *Engine) ServeGraphQLStream(request *Request) ResponseStream {
doc := &schema.QueryDocument{}
err := doc.Parse(request.Query)
if err != nil {
return NewErrStream(err)
}
op, err := doc.GetOperation(request.OperationName)
if err != nil {
return NewErrStream(err)
}
if engine.OnRequestHook != nil {
err := engine.OnRequestHook(request, doc, op)
if err != nil {
return NewErrStream(err)
}
}
if engine.Validate != nil {
err = engine.Validate(doc, engine.MaxDepth)
if err != nil {
return NewErrStream(err)
}
}
varTypes := make(map[string]*introspection.Type)
for _, v := range op.Vars {
t, err := schema.ResolveType(v.Type, engine.Schema.Resolve)
if err != nil {
return NewErrStream(err)
}
varTypes[v.Name] = introspection.WrapType(t)
}
ctx := request.GetContext()
traceContext, traceResponse, traceFinish := engine.Tracer.TraceQuery(ctx, request.Query, request.OperationName, request.Variables, varTypes)
variables, err := request.VariablesAsMap()
if err != nil {
return NewErrStream(err)
}
responses := make(chan *Response, 1)
r := exec.Execution{
Context: traceContext,
Query: request.Query,
Vars: variables,
Schema: engine.Schema,
Tracer: engine.Tracer,
Logger: engine.Logger,
Resolver: engine.Resolver,
Doc: doc,
Operation: op,
VarTypes: varTypes,
MaxParallelism: engine.MaxParallelism,
Root: engine.Root,
TryCast: engine.TryCast,
FireSubscriptionEventFunc: func(d json.RawMessage, e qerrors.ErrorList) {
responses <- &Response{
Data: d,
Errors: e,
}
traceResponse(e)
},
FireSubscriptionCloseFunc: func() {
close(responses)
doc.Close()
traceFinish()
},
}
err = r.Execute()
if err != nil {
return NewErrStream(err)
}
return responses
}
func (engine *Engine) validate(doc *schema.QueryDocument, maxDepth int) error {
errs := validation.Validate(engine.Schema, doc, maxDepth)
if len(errs) != 0 {
return errs.Error()
}
return nil
}