Use struct fields as resolvers instead of methods (graph-gophers#28)

.gitignore

@@ -1,3 +1,6 @@
 /internal/validation/testdata/graphql-js
 /internal/validation/testdata/node_modules
 /vendor
+.DS_Store
+.idea/
+.vscode/

config/config.go

@@ -0,0 +1,11 @@
+package config
+
+type Config struct {
+	UseResolverMethods bool
+}
+
+func Default() *Config {
+	return &Config{
+		UseResolverMethods: true,
+	}
+}

example/starwars/server/server.go

@@ -12,7 +12,7 @@ import (
 var schema *graphql.Schema
 
 func init() {
-	schema = graphql.MustParseSchema(starwars.Schema, &starwars.Resolver{})
+	schema = graphql.MustParseSchema(starwars.Schema, &starwars.Resolver{}, nil)
 }
 
 func main() {

graphql.go

@@ -2,9 +2,8 @@ package graphql
 
 import (
 	"context"
-	"fmt"
-
 	"encoding/json"
+	"fmt"
 
 	"github.com/graph-gophers/graphql-go/errors"
 	"github.com/graph-gophers/graphql-go/internal/common"

graphql_test.go

@@ -61,7 +61,7 @@ func (r *timeResolver) AddHour(args struct{ Time graphql.Time }) graphql.Time {
 	return graphql.Time{Time: args.Time.Add(time.Hour)}
 }
 
-var starwarsSchema = graphql.MustParseSchema(starwars.Schema, &starwars.Resolver{})
+var starwarsSchema = graphql.MustParseSchema(starwars.Schema, &starwars.Resolver{}, nil)
 
 func TestHelloWorld(t *testing.T) {
 	gqltesting.RunTests(t, []*gqltesting.Test{
@@ -74,7 +74,7 @@ func TestHelloWorld(t *testing.T) {
 				type Query {
 					hello: String!
 				}
-			`, &helloWorldResolver1{}),
+			`, &helloWorldResolver1{}, nil),
 			Query: `
 				{
 					hello
@@ -96,7 +96,7 @@ func TestHelloWorld(t *testing.T) {
 				type Query {
 					hello: String!
 				}
-			`, &helloWorldResolver2{}),
+			`, &helloWorldResolver2{}, nil),
 			Query: `
 				{
 					hello
@@ -122,7 +122,7 @@ func TestHelloSnake(t *testing.T) {
 				type Query {
 					hello_html: String!
 				}
-			`, &helloSnakeResolver1{}),
+			`, &helloSnakeResolver1{}, nil),
 			Query: `
 				{
 					hello_html
@@ -144,7 +144,7 @@ func TestHelloSnake(t *testing.T) {
 				type Query {
 					hello_html: String!
 				}
-			`, &helloSnakeResolver2{}),
+			`, &helloSnakeResolver2{}, nil),
 			Query: `
 				{
 					hello_html
@@ -170,7 +170,7 @@ func TestHelloSnakeArguments(t *testing.T) {
 				type Query {
 					say_hello(full_name: String!): String!
 				}
-			`, &helloSnakeResolver1{}),
+			`, &helloSnakeResolver1{}, nil),
 			Query: `
 				{
 					say_hello(full_name: "Rob Pike")
@@ -192,7 +192,7 @@ func TestHelloSnakeArguments(t *testing.T) {
 				type Query {
 					say_hello(full_name: String!): String!
 				}
-			`, &helloSnakeResolver2{}),
+			`, &helloSnakeResolver2{}, nil),
 			Query: `
 				{
 					say_hello(full_name: "Rob Pike")
@@ -606,7 +606,7 @@ func TestDeprecatedDirective(t *testing.T) {
 					b: Int! @deprecated
 					c: Int! @deprecated(reason: "We don't like it")
 				}
-			`, &testDeprecatedDirectiveResolver{}),
+			`, &testDeprecatedDirectiveResolver{}, nil),
 			Query: `
 				{
 					__type(name: "Query") {
@@ -650,7 +650,7 @@ func TestDeprecatedDirective(t *testing.T) {
 					B @deprecated
 					C @deprecated(reason: "We don't like it")
 				}
-			`, &testDeprecatedDirectiveResolver{}),
+			`, &testDeprecatedDirectiveResolver{}, nil),
 			Query: `
 				{
 					__type(name: "Test") {
@@ -1441,7 +1441,7 @@ func TestMutationOrder(t *testing.T) {
 				type Mutation {
 					changeTheNumber(newNumber: Int!): Query
 				}
-			`, &theNumberResolver{}),
+			`, &theNumberResolver{}, nil),
 			Query: `
 				mutation {
 					first: changeTheNumber(newNumber: 1) {
@@ -1485,7 +1485,7 @@ func TestTime(t *testing.T) {
 				}
 
 				scalar Time
-			`, &timeResolver{}),
+			`, &timeResolver{}, nil),
 			Query: `
 				query($t: Time!) {
 					a: addHour(time: $t)
@@ -1520,7 +1520,7 @@ func TestUnexportedMethod(t *testing.T) {
 		type Mutation {
 			changeTheNumber(newNumber: Int!): Int!
 		}
-	`, &resolverWithUnexportedMethod{})
+	`, &resolverWithUnexportedMethod{}, nil)
 	if err == nil {
 		t.Error("error expected")
 	}
@@ -1541,7 +1541,7 @@ func TestUnexportedField(t *testing.T) {
 		type Mutation {
 			changeTheNumber(newNumber: Int!): Int!
 		}
-	`, &resolverWithUnexportedField{})
+	`, &resolverWithUnexportedField{}, nil)
 	if err == nil {
 		t.Error("error expected")
 	}
@@ -1648,7 +1648,7 @@ func TestInput(t *testing.T) {
 			Option1
 			Option2
 		}
-	`, &inputResolver{})
+	`, &inputResolver{}, nil)
 	gqltesting.RunTests(t, []*gqltesting.Test{
 		{
 			Schema: coercionSchema,

internal/exec/exec.go

@@ -173,22 +173,28 @@ func execFieldSelection(ctx context.Context, r *Request, f *fieldToExec, path *p
 			return errors.Errorf("%s", err) // don't execute any more resolvers if context got cancelled
 		}
 
-		var in []reflect.Value
-		if f.field.HasContext {
-			in = append(in, reflect.ValueOf(traceCtx))
-		}
-		if f.field.ArgsPacker != nil {
-			in = append(in, f.field.PackedArgs)
-		}
-		callOut := f.resolver.Method(f.field.MethodIndex).Call(in)
-		result = callOut[0]
-		if f.field.HasError && !callOut[1].IsNil() {
-			resolverErr := callOut[1].Interface().(error)
-			err := errors.Errorf("%s", resolverErr)
-			err.Path = path.toSlice()
-			err.ResolverError = resolverErr
-			return err
+		if f.field.MethodIndex != -1 {
+			var in []reflect.Value
+			if f.field.HasContext {
+				in = append(in, reflect.ValueOf(traceCtx))
+			}
+			if f.field.ArgsPacker != nil {
+				in = append(in, f.field.PackedArgs)
+			}
+
+			callOut := f.resolver.Method(f.field.MethodIndex).Call(in)
+			result = callOut[0]
+			if f.field.HasError && !callOut[1].IsNil() {
+				resolverErr := callOut[1].Interface().(error)
+				err := errors.Errorf("%s", resolverErr)
+				err.Path = path.toSlice()
+				err.ResolverError = resolverErr
+				return err
+			}
+		} else {
+			result = f.resolver.Field(f.field.FieldIndex)
 		}
+
 		return nil
 	}()
 
@@ -201,7 +207,6 @@ func execFieldSelection(ctx context.Context, r *Request, f *fieldToExec, path *p
 		f.out.WriteString("null") // TODO handle non-nil
 		return
 	}
-
 	r.execSelectionSet(traceCtx, f.sels, f.field.Type, path, result, f.out)
 }