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omitempty for NULL attribute values from custom marshalers (#2739)
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babattles authored Aug 24, 2024
1 parent d7a7f5a commit 84ca95e
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9 changes: 9 additions & 0 deletions .changelog/281f2e28209e44068c04c9d74bab8970.json
Original file line number Diff line number Diff line change
@@ -0,0 +1,9 @@
{
"id": "281f2e28-209e-4406-8c04-c9d74bab8970",
"type": "feature",
"description": "Add Encoder option to obey omitempty tag for NULL attribute values.",
"modules": [
"feature/dynamodb/attributevalue",
"feature/dynamodbstreams/attributevalue"
]
}
14 changes: 14 additions & 0 deletions feature/dynamodb/attributevalue/encode.go
Original file line number Diff line number Diff line change
Expand Up @@ -392,6 +392,13 @@ type EncoderOptions struct {
// The results of a MarshalText call will convert to string (S), results
// from a MarshalBinary call will convert to binary (B).
UseEncodingMarshalers bool

// When enabled, the encoder will omit null (NULL) attribute values
// returned from custom marshalers tagged with `omitempty`.
//
// NULL attribute values returned from the standard marshaling routine will
// always respect omitempty regardless of this setting.
OmitNullAttributeValues bool
}

// An Encoder provides marshaling Go value types to AttributeValues.
Expand Down Expand Up @@ -452,6 +459,8 @@ func (e *Encoder) encode(v reflect.Value, fieldTag tag) (types.AttributeValue, e
if v.Kind() != reflect.Invalid {
if av, err := e.tryMarshaler(v); err != nil {
return nil, err
} else if e.options.OmitNullAttributeValues && fieldTag.OmitEmpty && isNullAttributeValue(av) {
return nil, nil
} else if av != nil {
return av, nil
}
Expand Down Expand Up @@ -893,3 +902,8 @@ func defaultEncodeTime(t time.Time) (types.AttributeValue, error) {
Value: t.Format(time.RFC3339Nano),
}, nil
}

func isNullAttributeValue(av types.AttributeValue) bool {
n, ok := av.(*types.AttributeValueMemberNULL)
return ok && n.Value
}
35 changes: 35 additions & 0 deletions feature/dynamodb/attributevalue/encode_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -420,6 +420,41 @@ func TestMarshalOmitEmpty(t *testing.T) {
}
}

type customNullMarshaler struct{}

func (m customNullMarshaler) MarshalDynamoDBAttributeValue() (types.AttributeValue, error) {
return &types.AttributeValueMemberNULL{Value: true}, nil
}

type testOmitEmptyCustom struct {
CustomNullOmit customNullMarshaler `dynamodbav:",omitempty"`
CustomNullOmitTagKey customNullMarshaler `tagkey:",omitempty"`
CustomNullPresent customNullMarshaler
EmptySetOmit []string `dynamodbav:",omitempty"`
}

func TestMarshalOmitEmptyCustom(t *testing.T) {
expect := &types.AttributeValueMemberM{
Value: map[string]types.AttributeValue{
"CustomNullPresent": &types.AttributeValueMemberNULL{Value: true},
},
}

m := testOmitEmptyCustom{}

actual, err := MarshalWithOptions(m, func(eo *EncoderOptions) {
eo.TagKey = "tagkey"
eo.OmitNullAttributeValues = true
eo.NullEmptySets = true
})
if err != nil {
t.Errorf("expect nil, got %v", err)
}
if e, a := expect, actual; !reflect.DeepEqual(e, a) {
t.Errorf("expect %v, got %v", e, a)
}
}

func TestEncodeEmbeddedPointerStruct(t *testing.T) {
type B struct {
Bint int
Expand Down
14 changes: 14 additions & 0 deletions feature/dynamodbstreams/attributevalue/encode.go
Original file line number Diff line number Diff line change
Expand Up @@ -392,6 +392,13 @@ type EncoderOptions struct {
// The results of a MarshalText call will convert to string (S), results
// from a MarshalBinary call will convert to binary (B).
UseEncodingMarshalers bool

// When enabled, the encoder will omit null (NULL) attribute values
// returned from custom marshalers tagged with `omitempty`.
//
// NULL attribute values returned from the standard marshaling routine will
// always respect omitempty regardless of this setting.
OmitNullAttributeValues bool
}

// An Encoder provides marshaling Go value types to AttributeValues.
Expand Down Expand Up @@ -452,6 +459,8 @@ func (e *Encoder) encode(v reflect.Value, fieldTag tag) (types.AttributeValue, e
if v.Kind() != reflect.Invalid {
if av, err := e.tryMarshaler(v); err != nil {
return nil, err
} else if e.options.OmitNullAttributeValues && fieldTag.OmitEmpty && isNullAttributeValue(av) {
return nil, nil
} else if av != nil {
return av, nil
}
Expand Down Expand Up @@ -893,3 +902,8 @@ func defaultEncodeTime(t time.Time) (types.AttributeValue, error) {
Value: t.Format(time.RFC3339Nano),
}, nil
}

func isNullAttributeValue(av types.AttributeValue) bool {
n, ok := av.(*types.AttributeValueMemberNULL)
return ok && n.Value
}
35 changes: 35 additions & 0 deletions feature/dynamodbstreams/attributevalue/encode_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -420,6 +420,41 @@ func TestMarshalOmitEmpty(t *testing.T) {
}
}

type customNullMarshaler struct{}

func (m customNullMarshaler) MarshalDynamoDBStreamsAttributeValue() (types.AttributeValue, error) {
return &types.AttributeValueMemberNULL{Value: true}, nil
}

type testOmitEmptyCustom struct {
CustomNullOmit customNullMarshaler `dynamodbav:",omitempty"`
CustomNullOmitTagKey customNullMarshaler `tagkey:",omitempty"`
CustomNullPresent customNullMarshaler
EmptySetOmit []string `dynamodbav:",omitempty"`
}

func TestMarshalOmitEmptyCustom(t *testing.T) {
expect := &types.AttributeValueMemberM{
Value: map[string]types.AttributeValue{
"CustomNullPresent": &types.AttributeValueMemberNULL{Value: true},
},
}

m := testOmitEmptyCustom{}

actual, err := MarshalWithOptions(m, func(eo *EncoderOptions) {
eo.TagKey = "tagkey"
eo.OmitNullAttributeValues = true
eo.NullEmptySets = true
})
if err != nil {
t.Errorf("expect nil, got %v", err)
}
if e, a := expect, actual; !reflect.DeepEqual(e, a) {
t.Errorf("expect %v, got %v", e, a)
}
}

func TestEncodeEmbeddedPointerStruct(t *testing.T) {
type B struct {
Bint int
Expand Down

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