Fix json string encoding

example/todo/todo_test.go

@@ -4,11 +4,10 @@ import (
 	"net/http/httptest"
 	"testing"
 
-	"github.com/vektah/gqlgen/client"
-	"github.com/vektah/gqlgen/neelance/introspection"
-
 	"github.com/stretchr/testify/require"
+	"github.com/vektah/gqlgen/client"
 	"github.com/vektah/gqlgen/handler"
+	"github.com/vektah/gqlgen/neelance/introspection"
 )
 
 func TestTodo(t *testing.T) {

graphql/string.go

@@ -6,9 +6,41 @@ import (
 	"strconv"
 )
 
+const alphabet = "0123456789ABCDEF"
+
 func MarshalString(s string) Marshaler {
 	return WriterFunc(func(w io.Writer) {
-		io.WriteString(w, strconv.Quote(s))
+		start := 0
+		io.WriteString(w, `"`)
+
+		for i := 0; i < len(s); i++ {
+			c := s[i]
+
+			if c < 0x20 || c == '\\' || c == '"' {
+				io.WriteString(w, s[start:i])
+
+				switch c {
+				case '\t':
+					io.WriteString(w, `\t`)
+				case '\r':
+					io.WriteString(w, `\r`)
+				case '\n':
+					io.WriteString(w, `\n`)
+				case '\\':
+					io.WriteString(w, `\\`)
+				case '"':
+					io.WriteString(w, `\"`)
+				default:
+					io.WriteString(w, `\u00`)
+					w.Write([]byte{alphabet[c>>4], alphabet[c&0xf]})
+				}
+
+				start = i + 1
+			}
+		}
+
+		io.WriteString(w, s[start:])
+		io.WriteString(w, `"`)
 	})
 }
 func UnmarshalString(v interface{}) (string, error) {

graphql/string_test.go

@@ -0,0 +1,27 @@
+package graphql
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestString(t *testing.T) {
+	assert.Equal(t, `"hello"`, doStrMarshal("hello"))
+	assert.Equal(t, `"he\tllo"`, doStrMarshal("he\tllo"))
+	assert.Equal(t, `"he\tllo"`, doStrMarshal("he	llo"))
+	assert.Equal(t, `"he\nllo"`, doStrMarshal("he\nllo"))
+	assert.Equal(t, `"he\r\nllo"`, doStrMarshal("he\r\nllo"))
+	assert.Equal(t, `"he\\llo"`, doStrMarshal(`he\llo`))
+	assert.Equal(t, `"quotes\"nested\"in\"quotes\""`, doStrMarshal(`quotes"nested"in"quotes"`))
+	assert.Equal(t, `"\u0000"`, doStrMarshal("\u0000"))
+	assert.Equal(t, `"\u0000"`, doStrMarshal("\u0000"))
+	assert.Equal(t, "\"\U000fe4ed\"", doStrMarshal("\U000fe4ed"))
+}
+
+func doStrMarshal(s string) string {
+	var buf bytes.Buffer
+	MarshalString(s).MarshalGQL(&buf)
+	return buf.String()
+}

handler/graphql.go

@@ -175,11 +175,12 @@ func GraphQL(exec graphql.ExecutableSchema, options ...Option) http.HandlerFunc
 			return
 		}
 
-		ctx := graphql.WithRequestContext(r.Context(), cfg.newRequestContext(doc, reqParams.Query, reqParams.Variables))
+		reqCtx := cfg.newRequestContext(doc, reqParams.Query, reqParams.Variables)
+		ctx := graphql.WithRequestContext(r.Context(), reqCtx)
 
 		defer func() {
 			if err := recover(); err != nil {
-				userErr := cfg.recover(ctx, err)
+				userErr := reqCtx.Recover(ctx, err)
 				sendErrorf(w, http.StatusUnprocessableEntity, userErr.Error())
 			}
 		}()

handler/websocket.go

@@ -154,7 +154,8 @@ func (c *wsConnection) subscribe(message *operationMessage) bool {
 		return true
 	}
 
-	ctx := graphql.WithRequestContext(c.ctx, c.cfg.newRequestContext(doc, reqParams.Query, reqParams.Variables))
+	reqCtx := c.cfg.newRequestContext(doc, reqParams.Query, reqParams.Variables)
+	ctx := graphql.WithRequestContext(c.ctx, reqCtx)
 
 	if op.Type != query.Subscription {
 		var result *graphql.Response
@@ -176,7 +177,7 @@ func (c *wsConnection) subscribe(message *operationMessage) bool {
 	go func() {
 		defer func() {
 			if r := recover(); r != nil {
-				userErr := c.cfg.recover(ctx, r)
+				userErr := reqCtx.Recover(ctx, r)
 				c.sendError(message.ID, &errors.QueryError{Message: userErr.Error()})
 			}
 		}()

test/resolvers_test.go

@@ -82,11 +82,28 @@ func TestInputDefaults(t *testing.T) {
 	require.True(t, called)
 }
 
+func TestJsonEncoding(t *testing.T) {
+	srv := httptest.NewServer(handler.GraphQL(MakeExecutableSchema(&testResolvers{})))
+	c := client.New(srv.URL)
+
+	var resp struct {
+		JsonEncoding string
+	}
+
+	err := c.Post(`{ jsonEncoding }`, &resp)
+	require.NoError(t, err)
+	require.Equal(t, "\U000fe4ed", resp.JsonEncoding)
+}
+
 type testResolvers struct {
 	err       error
 	queryDate func(ctx context.Context, filter models.DateFilter) (bool, error)
 }
 
+func (r *testResolvers) Query_jsonEncoding(ctx context.Context) (string, error) {
+	return "\U000fe4ed", nil
+}
+
 func (r *testResolvers) Query_viewer(ctx context.Context) (*Viewer, error) {
 	return &Viewer{
 		User: &remote_api.User{"Bob"},

test/schema.graphql

@@ -29,6 +29,7 @@ type Query {
     path: [Element]
     date(filter: DateFilter!): Boolean!
     viewer: Viewer
+    jsonEncoding: String!
 }
 
 // this is a comment with a `backtick`