Merge pull request #50 from graphql-go/pr-47

handler: support for optional resultCallbackFn

Author: chris-ramon

handler.go

@@ -18,12 +18,15 @@ const (
 	ContentTypeFormURLEncoded = "application/x-www-form-urlencoded"
 )
 
+type ResultCallbackFn func(ctx context.Context, params *graphql.Params, result *graphql.Result, responseBody []byte)
+
 type Handler struct {
-	Schema       *graphql.Schema
-	pretty       bool
-	graphiql     bool
-	playground   bool
-	rootObjectFn RootObjectFn
+	Schema           *graphql.Schema
+	pretty           bool
+	graphiql         bool
+	playground       bool
+	rootObjectFn     RootObjectFn
+	resultCallbackFn ResultCallbackFn
 }
 type RequestOptions struct {
 	Query         string                 `json:"query" url:"query" schema:"query"`
@@ -155,17 +158,22 @@ func (h *Handler) ContextHandler(ctx context.Context, w http.ResponseWriter, r *
 	// use proper JSON Header
 	w.Header().Add("Content-Type", "application/json; charset=utf-8")
 
+	var buff []byte
 	if h.pretty {
 		w.WriteHeader(http.StatusOK)
-		buff, _ := json.MarshalIndent(result, "", "\t")
+		buff, _ = json.MarshalIndent(result, "", "\t")
 
 		w.Write(buff)
 	} else {
 		w.WriteHeader(http.StatusOK)
-		buff, _ := json.Marshal(result)
+		buff, _ = json.Marshal(result)
 
 		w.Write(buff)
 	}
+
+	if h.resultCallbackFn != nil {
+		h.resultCallbackFn(ctx, &params, result, buff)
+	}
 }
 
 // ServeHTTP provides an entrypoint into executing graphQL queries.
@@ -177,11 +185,12 @@ func (h *Handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 type RootObjectFn func(ctx context.Context, r *http.Request) map[string]interface{}
 
 type Config struct {
-	Schema       *graphql.Schema
-	Pretty       bool
-	GraphiQL     bool
-	Playground   bool
-	RootObjectFn RootObjectFn
+	Schema           *graphql.Schema
+	Pretty           bool
+	GraphiQL         bool
+	Playground       bool
+	RootObjectFn     RootObjectFn
+	ResultCallbackFn ResultCallbackFn
 }
 
 func NewConfig() *Config {
@@ -202,10 +211,11 @@ func New(p *Config) *Handler {
 	}
 
 	return &Handler{
-		Schema:       p.Schema,
-		pretty:       p.Pretty,
-		graphiql:     p.GraphiQL,
-		playground:   p.Playground,
-		rootObjectFn: p.RootObjectFn,
+		Schema:           p.Schema,
+		pretty:           p.Pretty,
+		graphiql:         p.GraphiQL,
+		playground:       p.Playground,
+		rootObjectFn:     p.RootObjectFn,
+		resultCallbackFn: p.ResultCallbackFn,
 	}
 }

handler_test.go

@@ -93,12 +93,23 @@ func TestHandler_BasicQuery_Pretty(t *testing.T) {
 			},
 		},
 	}
-	queryString := `query=query HeroNameQuery { hero { name } }`
+	queryString := `query=query HeroNameQuery { hero { name } }&operationName=HeroNameQuery`
 	req, _ := http.NewRequest("GET", fmt.Sprintf("/graphql?%v", queryString), nil)
 
+	callbackCalled := false
 	h := handler.New(&handler.Config{
 		Schema: &testutil.StarWarsSchema,
 		Pretty: true,
+		ResultCallbackFn: func(ctx context.Context, params *graphql.Params, result *graphql.Result, responseBody []byte) {
+			callbackCalled = true
+			if params.OperationName != "HeroNameQuery" {
+				t.Fatalf("OperationName passed to callback was not HeroNameQuery: %v", params.OperationName)
+			}
+
+			if result.HasErrors() {
+				t.Fatalf("unexpected graphql result errors")
+			}
+		},
 	})
 	result, resp := executeTest(t, h, req)
 	if resp.Code != http.StatusOK {
@@ -107,6 +118,9 @@ func TestHandler_BasicQuery_Pretty(t *testing.T) {
 	if !reflect.DeepEqual(result, expected) {
 		t.Fatalf("wrong result, graphql result diff: %v", testutil.Diff(expected, result))
 	}
+	if !callbackCalled {
+		t.Fatalf("ResultCallbackFn was not called when it should have been")
+	}
 }
 
 func TestHandler_BasicQuery_Ugly(t *testing.T) {