1486: dynamo/attributevalue allow json tag encoding/decoding

feature/dynamodb/attributevalue/decode.go

@@ -114,6 +114,13 @@ func UnmarshalListOfMaps(l []map[string]types.AttributeValue, out interface{}) e
 // DecoderOptions is a collection of options to configure how the decoder
 // unmarshalls the value.
 type DecoderOptions struct {
+	// States that the encoding/json struct tags should be supported.
+	// if a `dynamodbav` struct tag is also provided the encoding/json
+	// tag will be ignored.
+	//
+	// Enabled by default.
+	SupportJSONTags bool
+
 	// Support other custom struct tag keys, such as `yaml`, `json`, or `toml`.
 	// Note that values provided with a custom TagKey must also be supported
 	// by the (un)marshalers in this package.
@@ -136,7 +143,10 @@ type Decoder struct {
 // NewDecoder creates a new Decoder with default configuration. Use
 // the `opts` functional options to override the default configuration.
 func NewDecoder(optFns ...func(*DecoderOptions)) *Decoder {
-	var options DecoderOptions
+	var options = DecoderOptions{
+		SupportJSONTags: true,
+	}
+
 	for _, fn := range optFns {
 		fn(&options)
 	}
@@ -509,7 +519,8 @@ func (d *Decoder) decodeMap(avMap map[string]types.AttributeValue, v reflect.Val
 		}
 	} else if v.Kind() == reflect.Struct {
 		fields := unionStructFields(v.Type(), structFieldOptions{
-			TagKey: d.options.TagKey,
+			TagKey:          d.options.TagKey,
+			SupportJSONTags: true,
 		})
 		for k, av := range avMap {
 			if f, ok := fields.FieldByName(k); ok {

feature/dynamodb/attributevalue/encode.go

@@ -212,6 +212,13 @@ func MarshalList(in interface{}) ([]types.AttributeValue, error) {
 // EncoderOptions is a collection of options shared between marshaling
 // and unmarshaling
 type EncoderOptions struct {
+	// States that the encoding/json struct tags should be supported.
+	// if a `dynamodbav` struct tag is also provided the encoding/json
+	// tag will be ignored.
+	//
+	// Enabled by default.
+	SupportJSONTags bool
+
 	// Support other custom struct tag keys, such as `yaml`, `json`, or `toml`.
 	// Note that values provided with a custom TagKey must also be supported
 	// by the (un)marshalers in this package.
@@ -241,7 +248,8 @@ type Encoder struct {
 // the `opts` functional options to override the default configuration.
 func NewEncoder(optFns ...func(*EncoderOptions)) *Encoder {
 	options := EncoderOptions{
-		NullEmptySets: true,
+		NullEmptySets:   true,
+		SupportJSONTags: true,
 	}
 	for _, fn := range optFns {
 		fn(&options)

feature/dynamodb/attributevalue/field.go

@@ -34,6 +34,13 @@ func buildField(pIdx []int, i int, sf reflect.StructField, fieldTag tag) field {
 }
 
 type structFieldOptions struct {
+	// States that the encoding/json struct tags should be supported.
+	// if a `dynamodbav` struct tag is also provided the encoding/json
+	// tag will be ignored.
+	//
+	// Enabled by default.
+	SupportJSONTags bool
+
 	// Support other custom struct tag keys, such as `yaml`, `json`, or `toml`.
 	// Note that values provided with a custom TagKey must also be supported
 	// by the (un)marshalers in this package.
@@ -107,6 +114,8 @@ func enumFields(t reflect.Type, opts structFieldOptions) []field {
 				// Because MarshalOptions.TagKey must be explicitly set.
 				if opts.TagKey != "" && fieldTag == (tag{}) {
 					fieldTag.parseStructTag(opts.TagKey, sf.Tag)
+				} else if opts.SupportJSONTags && fieldTag == (tag{}) {
+					fieldTag.parseStructTag("json", sf.Tag)
 				}
 
 				if fieldTag.Ignore {