Merge pull request #448 from Fontinalis/extensions

Add extensions support

executor.go

@@ -29,9 +29,27 @@ func Execute(p ExecuteParams) (result *Result) {
 	if ctx == nil {
 		ctx = context.Background()
 	}
+	// run executionDidStart functions from extensions
+	extErrs, executionFinishFn := handleExtensionsExecutionDidStart(&p)
+	if len(extErrs) != 0 {
+		return &Result{
+			Errors: extErrs,
+		}
+	}
+
+	defer func() {
+		extErrs = executionFinishFn(result)
+		if len(extErrs) != 0 {
+			result.Errors = append(result.Errors, extErrs...)
+		}
+
+		addExtensionResults(&p, result)
+	}()
 
 	resultChannel := make(chan *Result)
-	result = &Result{}
+	result = &Result{
+		Extensions: map[string]interface{}{},
+	}
 
 	go func(out chan<- *Result, done <-chan struct{}) {
 		defer func() {
@@ -63,6 +81,7 @@ func Execute(p ExecuteParams) (result *Result) {
 			Root:             p.Root,
 			Operation:        exeContext.Operation,
 		})
+
 	}(resultChannel, ctx.Done())
 
 	select {
@@ -71,6 +90,7 @@ func Execute(p ExecuteParams) (result *Result) {
 	case r := <-resultChannel:
 		result = r
 	}
+
 	return
 }
 
@@ -266,6 +286,7 @@ func executeFields(p executeFieldsParams) *Result {
 }
 
 func executeSubFields(p executeFieldsParams) map[string]interface{} {
+
 	if p.Source == nil {
 		p.Source = map[string]interface{}{}
 	}
@@ -620,6 +641,11 @@ func resolveField(eCtx *executionContext, parentType *Object, source interface{}
 
 	var resolveFnError error
 
+	extErrs, resolveFieldFinishFn := handleExtensionsResolveFieldDidStart(eCtx.Schema.extensions, eCtx, &info)
+	if len(extErrs) != 0 {
+		eCtx.Errors = append(eCtx.Errors, extErrs...)
+	}
+
 	result, resolveFnError = resolveFn(ResolveParams{
 		Source:  source,
 		Args:    args,
@@ -631,6 +657,11 @@ func resolveField(eCtx *executionContext, parentType *Object, source interface{}
 		panic(resolveFnError)
 	}
 
+	extErrs = resolveFieldFinishFn(result, resolveFnError)
+	if len(extErrs) != 0 {
+		eCtx.Errors = append(eCtx.Errors, extErrs...)
+	}
+
 	completed := completeValueCatchingError(eCtx, returnType, fieldASTs, info, path, result)
 	return completed, resultState
 }
@@ -902,7 +933,7 @@ type FieldResolver interface {
 	Resolve(p ResolveParams) (interface{}, error)
 }
 
-// defaultResolveFn If a resolve function is not given, then a default resolve behavior is used
+// DefaultResolveFn If a resolve function is not given, then a default resolve behavior is used
 // which takes the property of the source object of the same name as the field
 // and returns it as the result, or if it's a function, returns the result
 // of calling that function.

extensions.go

@@ -0,0 +1,251 @@
+package graphql
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/graphql-go/graphql/gqlerrors"
+)
+
+type (
+	// ParseFinishFunc is called when the parse of the query is done
+	ParseFinishFunc func(error)
+	// parseFinishFuncHandler handles the call of all the ParseFinishFuncs from the extenisons
+	parseFinishFuncHandler func(error) []gqlerrors.FormattedError
+
+	// ValidationFinishFunc is called when the Validation of the query is finished
+	ValidationFinishFunc func([]gqlerrors.FormattedError)
+	// validationFinishFuncHandler responsible for the call of all the ValidationFinishFuncs
+	validationFinishFuncHandler func([]gqlerrors.FormattedError) []gqlerrors.FormattedError
+
+	// ExecutionFinishFunc is called when the execution is done
+	ExecutionFinishFunc func(*Result)
+	// executionFinishFuncHandler calls all the ExecutionFinishFuncs from each extension
+	executionFinishFuncHandler func(*Result) []gqlerrors.FormattedError
+
+	// ResolveFieldFinishFunc is called with the result of the ResolveFn and the error it returned
+	ResolveFieldFinishFunc func(interface{}, error)
+	// resolveFieldFinishFuncHandler calls the resolveFieldFinishFns for all the extensions
+	resolveFieldFinishFuncHandler func(interface{}, error) []gqlerrors.FormattedError
+)
+
+// Extension is an interface for extensions in graphql
+type Extension interface {
+	// Init is used to help you initialize the extension
+	Init(context.Context, *Params) context.Context
+
+	// Name returns the name of the extension (make sure it's custom)
+	Name() string
+
+	// ParseDidStart is being called before starting the parse
+	ParseDidStart(context.Context) (context.Context, ParseFinishFunc)
+
+	// ValidationDidStart is called just before the validation begins
+	ValidationDidStart(context.Context) (context.Context, ValidationFinishFunc)
+
+	// ExecutionDidStart notifies about the start of the execution
+	ExecutionDidStart(context.Context) (context.Context, ExecutionFinishFunc)
+
+	// ResolveFieldDidStart notifies about the start of the resolving of a field
+	ResolveFieldDidStart(context.Context, *ResolveInfo) (context.Context, ResolveFieldFinishFunc)
+
+	// HasResult returns if the extension wants to add data to the result
+	HasResult() bool
+
+	// GetResult returns the data that the extension wants to add to the result
+	GetResult(context.Context) interface{}
+}
+
+// handleExtensionsInits handles all the init functions for all the extensions in the schema
+func handleExtensionsInits(p *Params) gqlerrors.FormattedErrors {
+	errs := gqlerrors.FormattedErrors{}
+	for _, ext := range p.Schema.extensions {
+		func() {
+			// catch panic from an extension init fn
+			defer func() {
+				if r := recover(); r != nil {
+					errs = append(errs, gqlerrors.FormatError(fmt.Errorf("%s.Init: %v", ext.Name(), r.(error))))
+				}
+			}()
+			// update context
+			p.Context = ext.Init(p.Context, p)
+		}()
+	}
+	return errs
+}
+
+// handleExtensionsParseDidStart runs the ParseDidStart functions for each extension
+func handleExtensionsParseDidStart(p *Params) ([]gqlerrors.FormattedError, parseFinishFuncHandler) {
+	fs := map[string]ParseFinishFunc{}
+	errs := gqlerrors.FormattedErrors{}
+	for _, ext := range p.Schema.extensions {
+		var (
+			ctx      context.Context
+			finishFn ParseFinishFunc
+		)
+		// catch panic from an extension's parseDidStart functions
+		func() {
+			defer func() {
+				if r := recover(); r != nil {
+					errs = append(errs, gqlerrors.FormatError(fmt.Errorf("%s.ParseDidStart: %v", ext.Name(), r.(error))))
+				}
+			}()
+			ctx, finishFn = ext.ParseDidStart(p.Context)
+			// update context
+			p.Context = ctx
+			fs[ext.Name()] = finishFn
+		}()
+	}
+	return errs, func(err error) []gqlerrors.FormattedError {
+		errs := gqlerrors.FormattedErrors{}
+		for name, fn := range fs {
+			func() {
+				// catch panic from a finishFn
+				defer func() {
+					if r := recover(); r != nil {
+						errs = append(errs, gqlerrors.FormatError(fmt.Errorf("%s.ParseFinishFunc: %v", name, r.(error))))
+					}
+				}()
+				fn(err)
+			}()
+		}
+		return errs
+	}
+}
+
+// handleExtensionsValidationDidStart notifies the extensions about the start of the validation process
+func handleExtensionsValidationDidStart(p *Params) ([]gqlerrors.FormattedError, validationFinishFuncHandler) {
+	fs := map[string]ValidationFinishFunc{}
+	errs := gqlerrors.FormattedErrors{}
+	for _, ext := range p.Schema.extensions {
+		var (
+			ctx      context.Context
+			finishFn ValidationFinishFunc
+		)
+		// catch panic from an extension's validationDidStart function
+		func() {
+			defer func() {
+				if r := recover(); r != nil {
+					errs = append(errs, gqlerrors.FormatError(fmt.Errorf("%s.ValidationDidStart: %v", ext.Name(), r.(error))))
+				}
+			}()
+			ctx, finishFn = ext.ValidationDidStart(p.Context)
+			// update context
+			p.Context = ctx
+			fs[ext.Name()] = finishFn
+		}()
+	}
+	return errs, func(errs []gqlerrors.FormattedError) []gqlerrors.FormattedError {
+		extErrs := gqlerrors.FormattedErrors{}
+		for name, finishFn := range fs {
+			func() {
+				// catch panic from a finishFn
+				defer func() {
+					if r := recover(); r != nil {
+						extErrs = append(extErrs, gqlerrors.FormatError(fmt.Errorf("%s.ValidationFinishFunc: %v", name, r.(error))))
+					}
+				}()
+				finishFn(errs)
+			}()
+		}
+		return extErrs
+	}
+}
+
+// handleExecutionDidStart handles the ExecutionDidStart functions
+func handleExtensionsExecutionDidStart(p *ExecuteParams) ([]gqlerrors.FormattedError, executionFinishFuncHandler) {
+	fs := map[string]ExecutionFinishFunc{}
+	errs := gqlerrors.FormattedErrors{}
+	for _, ext := range p.Schema.extensions {
+		var (
+			ctx      context.Context
+			finishFn ExecutionFinishFunc
+		)
+		// catch panic from an extension's executionDidStart function
+		func() {
+			defer func() {
+				if r := recover(); r != nil {
+					errs = append(errs, gqlerrors.FormatError(fmt.Errorf("%s.ExecutionDidStart: %v", ext.Name(), r.(error))))
+				}
+			}()
+			ctx, finishFn = ext.ExecutionDidStart(p.Context)
+			// update context
+			p.Context = ctx
+			fs[ext.Name()] = finishFn
+		}()
+	}
+	return errs, func(result *Result) []gqlerrors.FormattedError {
+		extErrs := gqlerrors.FormattedErrors{}
+		for name, finishFn := range fs {
+			func() {
+				// catch panic from a finishFn
+				defer func() {
+					if r := recover(); r != nil {
+						extErrs = append(extErrs, gqlerrors.FormatError(fmt.Errorf("%s.ExecutionFinishFunc: %v", name, r.(error))))
+					}
+				}()
+				finishFn(result)
+			}()
+		}
+		return extErrs
+	}
+}
+
+// handleResolveFieldDidStart handles the notification of the extensions about the start of a resolve function
+func handleExtensionsResolveFieldDidStart(exts []Extension, p *executionContext, i *ResolveInfo) ([]gqlerrors.FormattedError, resolveFieldFinishFuncHandler) {
+	fs := map[string]ResolveFieldFinishFunc{}
+	errs := gqlerrors.FormattedErrors{}
+	for _, ext := range p.Schema.extensions {
+		var (
+			ctx      context.Context
+			finishFn ResolveFieldFinishFunc
+		)
+		// catch panic from an extension's resolveFieldDidStart function
+		func() {
+			defer func() {
+				if r := recover(); r != nil {
+					errs = append(errs, gqlerrors.FormatError(fmt.Errorf("%s.ResolveFieldDidStart: %v", ext.Name(), r.(error))))
+				}
+			}()
+			ctx, finishFn = ext.ResolveFieldDidStart(p.Context, i)
+			// update context
+			p.Context = ctx
+			fs[ext.Name()] = finishFn
+		}()
+	}
+	return errs, func(val interface{}, err error) []gqlerrors.FormattedError {
+		extErrs := gqlerrors.FormattedErrors{}
+		for name, finishFn := range fs {
+			func() {
+				// catch panic from a finishFn
+				defer func() {
+					if r := recover(); r != nil {
+						extErrs = append(extErrs, gqlerrors.FormatError(fmt.Errorf("%s.ResolveFieldFinishFunc: %v", name, r.(error))))
+					}
+				}()
+				finishFn(val, err)
+			}()
+		}
+		return extErrs
+	}
+}
+
+func addExtensionResults(p *ExecuteParams, result *Result) {
+	if len(p.Schema.extensions) != 0 {
+		for _, ext := range p.Schema.extensions {
+			func() {
+				defer func() {
+					if r := recover(); r != nil {
+						result.AppendErrors(gqlerrors.FormatError(fmt.Errorf("%s.GetResult: %v", ext.Name(), r.(error))))
+					}
+				}()
+				if ext.HasResult() {
+					if result.Extensions == nil {
+						result.Extensions = make(map[string]interface{})
+					}
+					result.Extensions[ext.Name()] = ext.GetResult(p.Context)
+				}
+			}()
+		}
+	}
+}