fix(datastore): Handle loading nil values

datastore/integration_test.go

@@ -342,6 +342,34 @@ func TestIntegration_ListValues(t *testing.T) {
  }
 }
 
+func TestIntegration_PutGetUntypedNil(t *testing.T) {
+ ctx := context.Background()
+ client := newTestClient(ctx, t)
+ defer client.Close()
+
+ type X struct {
+ I interface{} `json:"i"`
+ }
+
+ putX := &X{
+ I: nil,
+ }
+ key, err := client.Put(ctx, IncompleteKey("X", nil), putX)
+ if err != nil {
+ t.Fatalf("client.Put got: %v, want: nil", err)
+ }
+
+ getX := &X{}
+ err = client.Get(ctx, key, getX)
+ if err != nil {
+ t.Fatalf("client.Get got: %v, want: nil", err)
+ }
+
+ if !reflect.DeepEqual(getX, putX) {
+ t.Fatalf("got: %v, want: %v", getX, putX)
+ }
+}
+
 func TestIntegration_GetMulti(t *testing.T) {
  ctx := context.Background()
  client := newTestClient(ctx, t)

datastore/load.go

@@ -302,11 +302,17 @@ func setVal(v reflect.Value, p Property) (s string) {
  return fmt.Sprintf("%v is unsettable", v.Type())
  }
 
- rpValue := reflect.ValueOf(pValue)
- if !rpValue.Type().AssignableTo(v.Type()) {
- return fmt.Sprintf("%q is not assignable to %q", rpValue.Type(), v.Type())
+ // When retrieved property value is untyped nil, its type cannot be determined
+ // So, set v to zero value of its datatype
+ if pValue == nil {
+ v.Set(reflect.Zero(v.Type()))
+ } else {
+ rpValue := reflect.ValueOf(pValue)
+ if !rpValue.Type().AssignableTo(v.Type()) {
+ return fmt.Sprintf("%q is not assignable to %q", rpValue.Type(), v.Type())
+ }
+ v.Set(rpValue)
  }
- v.Set(rpValue)
 
  case reflect.Ptr:
  // v must be a pointer to either a Key, an Entity, or one of the supported basic types.

datastore/load_test.go

@@ -1290,6 +1290,27 @@ func TestLoadNull(t *testing.T) {
  }
 }
 
+func TestLoadNilInterface(t *testing.T) {
+ type WithAny struct {
+ AnyField interface{}
+ }
+
+ withAny1 := &WithAny{}
+ err := loadEntityProto(withAny1, &pb.Entity{
+ Key: keyToProto(testKey0),
+ Properties: map[string]*pb.Value{
+ "AnyField": {ValueType: &pb.Value_NullValue{}},
+ },
+ })
+ if err != nil {
+ t.Fatalf("loadEntityProto got: %v, want: nil", err)
+ }
+
+ if withAny1.AnyField != nil {
+ t.Fatalf("got: %v, want: nil", withAny1.AnyField)
+ }
+}
+
 type KeyLoaderEnt struct {
  A int
  K *Key