graphql: Updated mutation rewriting to fix OOM issue

graphql/admin/add_group.go

@@ -21,7 +21,7 @@ func NewAddGroupRewriter() resolve.MutationRewriter {
 // A rule is duplicate if it has same predicate name as another rule.
 func (mrw *addGroupRewriter) Rewrite(
 	ctx context.Context,
-	m schema.Mutation) (*resolve.UpsertMutation, error) {
+	m schema.Mutation) ([]*resolve.UpsertMutation, error) {
 
 	addGroupInput, _ := m.ArgValue(schema.InputArgName).([]interface{})
 

graphql/admin/schema.go

@@ -63,7 +63,7 @@ type updateGQLSchemaInput struct {
 
 func (asr *updateSchemaResolver) Rewrite(
 	ctx context.Context,
-	m schema.Mutation) (*resolve.UpsertMutation, error) {
+	m schema.Mutation) ([]*resolve.UpsertMutation, error) {
 
 	glog.Info("Got updateGQLSchema request")
 

graphql/admin/update_group.go

@@ -3,6 +3,7 @@ package admin
 import (
 	"context"
 	"fmt"
+
 	dgoapi "github.com/dgraph-io/dgo/v2/protos/api"
 	"github.com/dgraph-io/dgraph/gql"
 	"github.com/dgraph-io/dgraph/graphql/resolve"
@@ -23,7 +24,7 @@ func NewUpdateGroupRewriter() resolve.MutationRewriter {
 // name as another rule.
 func (urw *updateGroupRewriter) Rewrite(
 	ctx context.Context,
-	m schema.Mutation) (*resolve.UpsertMutation, error) {
+	m schema.Mutation) ([]*resolve.UpsertMutation, error) {
 
 	inp := m.ArgValue(schema.InputArgName).(map[string]interface{})
 	setArg := inp["set"]
@@ -125,10 +126,10 @@ func (urw *updateGroupRewriter) Rewrite(
 		return nil, nil
 	}
 
-	return &resolve.UpsertMutation{
+	return []*resolve.UpsertMutation{{
 		Query:     &gql.GraphQuery{Children: []*gql.GraphQuery{upsertQuery}},
 		Mutations: append(mutSet, mutDel...),
-	}, schema.GQLWrapf(schema.AppendGQLErrs(errSet, errDel), "failed to rewrite mutation payload")
+	}}, schema.GQLWrapf(schema.AppendGQLErrs(errSet, errDel), "failed to rewrite mutation payload")
 }
 
 // FromMutationResult rewrites the query part of a GraphQL update mutation into a Dgraph query.

graphql/e2e/common/common.go

@@ -298,6 +298,7 @@ func RunAll(t *testing.T) {
 	t.Run("password in mutation", passwordTest)
 	t.Run("duplicate xid in single mutation", deepMutationDuplicateXIDsSameObjectTest)
 	t.Run("alias works for mutations", mutationsWithAlias)
+	t.Run("three level deep", threeLevelDeepMutation)
 
 	// error tests
 	t.Run("graphql completion on", graphQLCompletionOn)

graphql/e2e/common/mutation.go

@@ -1292,8 +1292,8 @@ func updateMutationOnlyUpdatesRefsIfDifferent(t *testing.T, executeRequest reque
 					set: $set
 				}
 			) {
-			  	post { 
-					postID 
+			  	post {
+					postID
 					text
 					author { id }
 				}
@@ -1313,9 +1313,9 @@ func updateMutationOnlyUpdatesRefsIfDifferent(t *testing.T, executeRequest reque
 	// The text is updated as expected
 	// The author is unchanged
 	expected := fmt.Sprintf(`
-		{ "updatePost": {  "post": [ 
-			{ 
-				"postID": "%s", 
+		{ "updatePost": {  "post": [
+			{
+				"postID": "%s",
 				"text": "The Updated Text",
 				"author": { "id": "%s" }
 			}
@@ -2863,6 +2863,79 @@ func passwordTest(t *testing.T) {
 	deleteUser(t, *newUser)
 }
 
+func threeLevelDeepMutation(t *testing.T) {
+	newStudent := &student{
+		Xid:  "HS1",
+		Name: "Stud1",
+		TaughtBy: []*teacher{
+			{
+				Xid:     "HT0",
+				Name:    "Teacher0",
+				Subject: "English",
+				Teaches: []*student{{
+					Xid:  "HS2",
+					Name: "Stud2",
+				}},
+			},
+		},
+	}
+
+	newStudents := []*student{newStudent}
+
+	addStudentParams := &GraphQLParams{
+		Query: `mutation addStudent($input: [AddStudentInput!]!) {
+			addStudent(input: $input) {
+				student {
+					xid
+					name
+					taughtBy {
+						id
+						xid
+						name
+						subject
+						teaches (order: {asc:xid}) {
+							xid
+							taughtBy {
+								name
+								xid
+								subject
+							}
+						}
+					}
+				}
+			}
+		}`,
+		Variables: map[string]interface{}{"input": newStudents},
+	}
+
+	gqlResponse := postExecutor(t, graphqlURL, addStudentParams)
+	fmt.Println(string(gqlResponse.Data))
+	requireNoGQLErrors(t, gqlResponse)
+
+	var actualResult struct {
+		AddStudent struct {
+			Student []*student
+		}
+	}
+
+	err := json.Unmarshal(gqlResponse.Data, &actualResult)
+	require.NoError(t, err)
+
+	require.Equal(t, actualResult.AddStudent.Student[0].Xid, "HS1")
+	require.Equal(t, actualResult.AddStudent.Student[0].TaughtBy[0].Xid, "HT0")
+	require.Equal(t, actualResult.AddStudent.Student[0].TaughtBy[0].Teaches[0].Xid, "HS1")
+	require.Equal(t, actualResult.AddStudent.Student[0].TaughtBy[0].Teaches[0].TaughtBy[0].Xid, "HT0")
+	require.Equal(t, actualResult.AddStudent.Student[0].TaughtBy[0].Teaches[1].Xid, "HS2")
+	require.Equal(t, actualResult.AddStudent.Student[0].TaughtBy[0].Teaches[1].TaughtBy[0].Xid, "HT0")
+
+	// cleanup
+	filter := getXidFilter("xid", []string{"HS1", "HS2"})
+	deleteGqlType(t, "Student", filter, 2, nil)
+	filter = getXidFilter("xid", []string{"HT0"})
+	deleteGqlType(t, "Teacher", filter, 1, nil)
+
+}
+
 func deepMutationDuplicateXIDsSameObjectTest(t *testing.T) {
 	newStudents := []*student{
 		{

graphql/e2e/directives/schema.graphql

@@ -136,9 +136,8 @@ type Teacher implements People {
 }
 
 type Student implements People {
-        taughtBy: [Teacher]
+        taughtBy: [Teacher] @hasInverse(field: "teaches")
 }
-
 type Message {
     content: String! @dgraph(pred: "post")
     author: String @dgraph(pred: "<职业>")

graphql/e2e/normal/schema.graphql

@@ -136,6 +136,6 @@ type Teacher implements People {
 }
 
 type Student implements People {
-        taughtBy: [Teacher]
+        taughtBy: [Teacher] @hasInverse(field: teaches)
 }