Add DeleteEdges function to client and fix small issues on server.

Author: Pawan Rawal

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project will adhere to [Semantic Versioning](http://semver.org/spec/v2.
 
 * Support for removing dead node from quorum.
 * Support for alias in groupby queries.
+* Add DeleteEdges helper function for Go client.
 
 ### Changed
 

client/client.go

@@ -78,3 +78,18 @@ func (d *Dgraph) Alter(ctx context.Context, op *protos.Operation) error {
 func (d *Dgraph) anyClient() protos.DgraphClient {
 	return d.dc[rand.Intn(len(d.dc))]
 }
+
+// DeleteEdges sets the edges corresponding to predicates on the node with the given uid
+// for deletion.
+// This helper function doesn't run the mutation on the server. It must be done by the user
+// after the function returns.
+func DeleteEdges(mu *protos.Mutation, uid string, predicates ...string) {
+	for _, predicate := range predicates {
+		mu.Del = append(mu.Del, &protos.NQuad{
+			Subject:   uid,
+			Predicate: predicate,
+			// _STAR_ALL is defined as x.Star in x package.
+			ObjectValue: &protos.Value{&protos.Value_DefaultVal{"_STAR_ALL"}},
+		})
+	}
+}

client/example_set_object_test.go

@@ -5,6 +5,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"log"
+	"time"
 
 	"github.com/dgraph-io/dgraph/client"
 	"github.com/dgraph-io/dgraph/protos"
@@ -24,14 +25,15 @@ type loc struct {
 // for bool) would be created for values not specified explicitly.
 
 type Person struct {
-	Uid      string   `json:"uid,omitempty"`
-	Name     string   `json:"name,omitempty"`
-	Age      int      `json:"age,omitempty"`
-	Married  bool     `json:"married,omitempty"`
-	Raw      []byte   `json:"raw_bytes",omitempty`
-	Friends  []Person `json:"friend,omitempty"`
-	Location loc      `json:"loc,omitempty"`
-	School   []School `json:"school,omitempty"`
+	Uid      string     `json:"uid,omitempty"`
+	Name     string     `json:"name,omitempty"`
+	Age      int        `json:"age,omitempty"`
+	Dob      *time.Time `json:"dob,omitempty"`
+	Married  bool       `json:"married,omitempty"`
+	Raw      []byte     `json:"raw_bytes",omitempty`
+	Friends  []Person   `json:"friend,omitempty"`
+	Location loc        `json:"loc,omitempty"`
+	School   []School   `json:"school,omitempty"`
 }
 
 func Example_setObject() {
@@ -50,6 +52,7 @@ func Example_setObject() {
 	// have a Uid).  Alice is also connected via the friend edge to an existing node with Uid
 	// 1000(Bob).  We also set Name and Age values for this node with Uid 1000.
 
+	dob := time.Date(1980, 01, 01, 23, 0, 0, 0, time.UTC)
 	p := Person{
 		Name:    "Alice",
 		Age:     26,
@@ -58,6 +61,7 @@ func Example_setObject() {
 			Type:   "Point",
 			Coords: []float64{1.1, 2},
 		},
+		Dob: &dob,
 		Raw: []byte("raw_bytes"),
 		Friends: []Person{{
 			Uid:  "1000",
@@ -77,6 +81,7 @@ func Example_setObject() {
 		age: int .
 		married: bool .
 		loc: geo .
+		dob: datetime .
 	`
 
 	ctx := context.Background()
@@ -105,6 +110,7 @@ func Example_setObject() {
 		me(func: uid(%s)) {
 			uid
 			name
+			dob
 			age
 			loc
 			raw_bytes

client/examples_test.go

@@ -604,7 +604,7 @@ func ExampleTxn_Mutate_list(t *testing.T) {
 	fmt.Printf("Me: %+v\n", r.Me)
 }
 
-func ExampleTxn_Mutate_delete() {
+func ExampleDeleteEdges() {
 	conn, err := grpc.Dial("127.0.0.1:9080", grpc.WithInsecure())
 	if err != nil {
 		log.Fatal("While trying to dial gRPC")
@@ -631,22 +631,18 @@ func ExampleTxn_Mutate_delete() {
 
 	// Lets add some data first.
 	p := Person{
-		Uid:      "1000",
 		Name:     "Alice",
 		Age:      26,
 		Married:  true,
 		Location: "Riley Street",
 		Friends: []Person{{
-			Uid:  "1001",
 			Name: "Bob",
 			Age:  24,
 		}, {
-			Uid:  "1002",
 			Name: "Charlie",
 			Age:  29,
 		}},
 		School: []*School{&School{
-			Uid:  "1003",
 			Name: "Crown Public School",
 		}},
 	}
@@ -671,13 +667,14 @@ func ExampleTxn_Mutate_delete() {
 
 	mu.SetJson = pb
 	mu.CommitNow = true
-	_, err = dg.NewTxn().Mutate(ctx, mu)
+	assigned, err := dg.NewTxn().Mutate(ctx, mu)
 	if err != nil {
 		log.Fatal(err)
 	}
 
+	uid := assigned.Uids["blank-0"]
 	q := fmt.Sprintf(`{
-		me(func: uid(1000)) {
+		me(func: uid(%s)) {
 			uid
 			name
 			age
@@ -693,45 +690,19 @@ func ExampleTxn_Mutate_delete() {
 				name@en
 			}
 		}
-
-		me2(func: uid(1001)) {
-			uid
-			name
-			age
-		}
-
-		me3(func: uid(1003)) {
-			uid
-			name@en
-		}
-
-		me4(func: uid(1002)) {
-			uid
-			name
-			age
-		}
-	}`)
+	}`, uid)
 
 	resp, err := dg.NewTxn().Query(ctx, q)
 	if err != nil {
 		log.Fatal(err)
 	}
 
-	// Now lets delete the edge between Alice and Bob.
-	// Also lets delete the location for Alice.
-	p2 := Person{
-		Uid:      "1000",
-		Location: "",
-		Friends:  []Person{Person{Uid: "1001"}},
-	}
+	fmt.Println(string(resp.Json))
 
+	// Now lets delete the friend and location edge from Alice
 	mu = &protos.Mutation{}
-	pb, err = json.Marshal(p2)
-	if err != nil {
-		log.Fatal(err)
-	}
+	client.DeleteEdges(mu, uid, "friend", "loc")
 
-	mu.DeleteJson = pb
 	mu.CommitNow = true
 	_, err = dg.NewTxn().Mutate(ctx, mu)
 	if err != nil {
@@ -744,10 +715,7 @@ func ExampleTxn_Mutate_delete() {
 	}
 
 	type Root struct {
-		Me  []Person `json:"me"`
-		Me2 []Person `json:"me2"`
-		Me3 []School `json:"me3"`
-		Me4 []Person `json:"me4"`
+		Me []Person `json:"me"`
 	}
 
 	var r Root

dgraph/cmd/live/run.go

@@ -212,7 +212,9 @@ func setupConnection(host string, insecure bool) (*grpc.ClientConn, error) {
 			grpc.WithDefaultCallOptions(
 				grpc.MaxCallRecvMsgSize(x.GrpcMaxSize),
 				grpc.MaxCallSendMsgSize(x.GrpcMaxSize)),
-			grpc.WithInsecure())
+			grpc.WithInsecure(),
+			grpc.WithBlock(),
+			grpc.WithTimeout(10*time.Second))
 	}
 
 	tlsConf.ConfigType = x.TLSClientConfig
@@ -228,7 +230,7 @@ func setupConnection(host string, insecure bool) (*grpc.ClientConn, error) {
 			grpc.MaxCallSendMsgSize(x.GrpcMaxSize)),
 		grpc.WithTransportCredentials(credentials.NewTLS(tlsCfg)),
 		grpc.WithBlock(),
-		grpc.WithTimeout(5*time.Second))
+		grpc.WithTimeout(10*time.Second))
 }
 
 func fileList(files string) []string {
@@ -250,7 +252,7 @@ func setup(opts batchMutationOptions, dc *client.Dgraph) *loader {
 	x.Checkf(err, "Error while creating badger KV posting store")
 
 	connzero, err := setupConnection(opt.zero, true)
-	x.Checkf(err, "While trying to dial gRPC")
+	x.Checkf(err, "While trying to setup connection to Zero")
 
 	alloc := xidmap.New(kv,
 		&uidProvider{
@@ -308,7 +310,7 @@ func run() {
 	var clients []protos.DgraphClient
 	for _, d := range ds {
 		conn, err := setupConnection(d, !tlsConf.CertRequired)
-		x.Checkf(err, "While trying to dial gRPC")
+		x.Checkf(err, "While trying to setup connection to Dgraph server.")
 		defer conn.Close()
 
 		dc := protos.NewDgraphClient(conn)

dgraph/cmd/server/run_test.go

@@ -1362,6 +1362,11 @@ func TestMain(m *testing.M) {
 	}
 	time.Sleep(10 * time.Millisecond)
 
+	// Increment lease, so that mutations work.
+	_, err = worker.AssignUidsOverNetwork(context.Background(), &protos.Num{Val: 10e6})
+	if err != nil {
+		log.Fatal(err)
+	}
 	// Parse GQL into internal query representation.
 	r := m.Run()
 	closeAll(dir1, dir2)

edgraph/server.go

@@ -193,6 +193,13 @@ func (s *ServerState) getTimestamp() uint64 {
 
 func (s *Server) Alter(ctx context.Context, op *protos.Operation) (*protos.Payload, error) {
 	empty := &protos.Payload{}
+	if err := x.HealthCheck(); err != nil {
+		if tr, ok := trace.FromContext(ctx); ok {
+			tr.LazyPrintf("Request rejected %v", err)
+		}
+		return empty, err
+	}
+
 	if op.DropAll {
 		m := protos.Mutations{DropAll: true}
 		_, err := query.ApplyMutations(ctx, &m)
@@ -233,6 +240,13 @@ func (s *Server) Alter(ctx context.Context, op *protos.Operation) (*protos.Paylo
 
 func (s *Server) Mutate(ctx context.Context, mu *protos.Mutation) (resp *protos.Assigned, err error) {
 	resp = &protos.Assigned{}
+	if err := x.HealthCheck(); err != nil {
+		if tr, ok := trace.FromContext(ctx); ok {
+			tr.LazyPrintf("Request rejected %v", err)
+		}
+		return resp, err
+	}
+
 	if !isMutationAllowed(ctx) {
 		return nil, x.Errorf("No mutations allowed.")
 	}
@@ -296,7 +310,6 @@ func (s *Server) Mutate(ctx context.Context, mu *protos.Mutation) (resp *protos.
 // This method is used to execute the query and return the response to the
 // client as a protocol buffer message.
 func (s *Server) Query(ctx context.Context, req *protos.Request) (resp *protos.Response, err error) {
-	// we need membership information
 	if err := x.HealthCheck(); err != nil {
 		if tr, ok := trace.FromContext(ctx); ok {
 			tr.LazyPrintf("Request rejected %v", err)
@@ -388,6 +401,13 @@ func (s *Server) Query(ctx context.Context, req *protos.Request) (resp *protos.R
 
 func (s *Server) CommitOrAbort(ctx context.Context, tc *protos.TxnContext) (*protos.TxnContext,
 	error) {
+	if err := x.HealthCheck(); err != nil {
+		if tr, ok := trace.FromContext(ctx); ok {
+			tr.LazyPrintf("Request rejected %v", err)
+		}
+		return &protos.TxnContext{}, err
+	}
+
 	commitTs, err := worker.CommitOverNetwork(ctx, tc)
 	return &protos.TxnContext{
 		CommitTs: commitTs,
@@ -564,12 +584,19 @@ func mapToNquads(m map[string]interface{}, idx *int, op int, parentPred string)
 				uid = uint64(u)
 			}
 		}
+
 		if uid > 0 {
 			mr.uid = fmt.Sprintf("%d", uid)
 		}
+
 	}
 
-	if len(mr.uid) == 0 && op != delete {
+	if len(mr.uid) == 0 {
+		if op == delete {
+			// Delete operations with a non-nil value must have a uid specified.
+			return mr, x.Errorf("uid must be present and non-zero while deleting edges.")
+		}
+
 		mr.uid = fmt.Sprintf("_:blank-%d", *idx)
 		*idx++
 	}
@@ -584,17 +611,14 @@ func mapToNquads(m map[string]interface{}, idx *int, op int, parentPred string)
 		}
 
 		if op == delete {
-			// This corresponds to predicate deletion.
+			// This corresponds to edge deletion.
 			if v == nil {
 				mr.nquads = append(mr.nquads, &protos.NQuad{
-					Subject:     x.Star,
+					Subject:     mr.uid,
 					Predicate:   pred,
 					ObjectValue: &protos.Value{&protos.Value_DefaultVal{x.Star}},
 				})
 				continue
-			} else if len(mr.uid) == 0 {
-				// Delete operations with a non-nil value must have a uid specified.
-				return mr, x.Errorf("uid must be present and non-zero. Got: %+v", m)
 			}
 		}
 

edgraph/server_test.go

@@ -158,6 +158,13 @@ func TestNquadsFromJson4(t *testing.T) {
 	require.Contains(t, nq, makeNquad("_:blank-0", "name", oval))
 }
 
+func TestNquadsDeleteEdges(t *testing.T) {
+	json := `[{"uid": "0x1","name":null,"mobile":null,"car":null}]`
+	nq, err := nquadsFromJson([]byte(json), delete)
+	require.NoError(t, err)
+	require.Equal(t, 3, len(nq))
+}
+
 func checkCount(t *testing.T, nq []*protos.NQuad, pred string, count int) {
 	for _, n := range nq {
 		if n.Predicate == pred {
@@ -200,7 +207,7 @@ func TestNquadsFromJsonError1(t *testing.T) {
 
 	_, err = nquadsFromJson(b, delete)
 	require.Error(t, err)
-	require.Contains(t, err.Error(), "uid must be present and non-zero.")
+	require.Contains(t, err.Error(), "uid must be present and non-zero while deleting edges.")
 }
 
 func TestNquadsFromJsonList(t *testing.T) {