fix(GraphQL): Requesting only __typename now returns results

graphql/e2e/common/common.go

@@ -263,6 +263,8 @@ func RunAll(t *testing.T) {
 	t.Run("query typename", queryTypename)
 	t.Run("query nested typename", queryNestedTypename)
 	t.Run("typename for interface", typenameForInterface)
+	t.Run("query only typename", queryOnlyTypename)
+	t.Run("query nested only typename", queryNestedOnlyTypename)
 
 	t.Run("get state by xid", getStateByXid)
 	t.Run("get state without args", getStateWithoutArgs)

graphql/e2e/common/query.go

@@ -1169,6 +1169,101 @@ func queryNestedTypename(t *testing.T) {
 	testutil.CompareJSON(t, expected, string(gqlResponse.Data))
 }
 
+func queryOnlyTypename(t *testing.T) {
+	var countryCountResp struct {
+		QueryCountry []*country
+	}
+
+	getCountryParams := &GraphQLParams{
+		Query: `query queryCountry {
+			queryCountry {
+				id
+			}
+		}`,
+	}
+	gqlResponse := getCountryParams.ExecuteAsPost(t, graphqlURL)
+	RequireNoGQLErrors(t, gqlResponse)
+	require.NoError(t, json.Unmarshal([]byte(gqlResponse.Data), &countryCountResp))
+	require.True(t, len(countryCountResp.QueryCountry) > 0)
+
+	getCountryParams = &GraphQLParams{
+		Query: `query queryCountry {
+			queryCountry {
+				__typename
+			}
+		}`,
+	}
+	gqlResponse = getCountryParams.ExecuteAsPost(t, graphqlURL)
+	RequireNoGQLErrors(t, gqlResponse)
+
+	expectedResponse := `{
+	"queryCountry": [%s
+        ]
+}`
+	var builder strings.Builder
+	for i := 0; i < len(countryCountResp.QueryCountry); i++ {
+		builder.WriteString(`
+          {
+                "__typename": "Country"
+          }`)
+		if i != len(countryCountResp.QueryCountry)-1 {
+			builder.WriteString(",")
+		}
+	}
+	expectedResponse = fmt.Sprintf(expectedResponse, builder.String())
+
+	require.JSONEq(t, expectedResponse, string(gqlResponse.Data))
+}
+
+func queryNestedOnlyTypename(t *testing.T) {
+	var authorCountResp struct {
+		QueryAuthor []*author
+	}
+
+	getCountryParams := &GraphQLParams{
+		Query: `query {
+			queryAuthor {
+				id
+			}
+		}`,
+	}
+	gqlResponse := getCountryParams.ExecuteAsPost(t, graphqlURL)
+	RequireNoGQLErrors(t, gqlResponse)
+	require.NoError(t, json.Unmarshal([]byte(gqlResponse.Data), &authorCountResp))
+	require.True(t, len(authorCountResp.QueryAuthor) > 0)
+
+	getCountryParams = &GraphQLParams{
+		Query: `query {
+			queryAuthor {
+				country {
+					__typename
+				}
+			}
+		}`,
+	}
+	gqlResponse = getCountryParams.ExecuteAsPost(t, graphqlURL)
+	RequireNoGQLErrors(t, gqlResponse)
+
+	expectedResponse := `{
+	"queryAuthor": [%s
+        ]
+}`
+	var builder strings.Builder
+	for i := 0; i < len(authorCountResp.QueryAuthor); i++ {
+		builder.WriteString(`
+          {
+                "country": {
+                  "__typename": "Country"
+                }
+          }`)
+		if i != len(authorCountResp.QueryAuthor)-1 {
+			builder.WriteString(",")
+		}
+	}
+	expectedResponse = fmt.Sprintf(expectedResponse, builder.String())
+
+	require.JSONEq(t, expectedResponse, string(gqlResponse.Data))
+}
 func typenameForInterface(t *testing.T) {
 	newStarship := addStarship(t)
 	humanID := addHuman(t, newStarship.ID)

graphql/resolve/query_rewriter.go

@@ -376,6 +376,13 @@ func rewriteAsQuery(field schema.Field, authRw *authRewriter) *gql.GraphQuery {
 	return dgQuery
 }
 
+func (authRw *authRewriter) writingAuth() bool {
+	if authRw == nil || !authRw.isWritingAuth {
+		return false
+	}
+	return true
+}
+
 // addAuthQueries takes a field and the GraphQuery that has so far been constructed for
 // the field and builds any auth queries that are need to restrict the result to only
 // the nodes authorized to be queried, returning a new graphQuery that does the
@@ -596,11 +603,17 @@ func addSelectionSetFrom(
 	// Only add dgraph.type as a child if this field is an interface type and has some children.
 	// dgraph.type would later be used in completeObject as different objects in the resulting
 	// JSON would return different fields based on their concrete type.
-	if field.InterfaceType() && len(field.SelectionSet()) > 0 {
+	selSet := field.SelectionSet()
+	if len(selSet) > 0 &&
+		(field.InterfaceType() ||
+			(!auth.writingAuth() &&
+				len(selSet) == 1 &&
+				selSet[0].Name() == schema.Typename)) {
 		q.Children = append(q.Children, &gql.GraphQuery{
 			Attr: "dgraph.type",
 		})
 	}
+	selSet = nil
 
 	// These fields might not have been requested by the user directly as part of the query but
 	// are required in the body template for other fields requested within the query. We must