feat(x/tx): add an option to encode maps using amino json (backport #23539) (#23540)

Co-authored-by: Julien Robert <julien@rbrt.fr>

x/tx/CHANGELOG.md

@@ -33,9 +33,11 @@ Since v0.13.0, x/tx follows Cosmos SDK semver: https://github.com/cosmos/cosmos-
 
 ## [Unreleased]
 
-## [v0.13.7](https://github.com/cosmos/cosmos-sdk/releases/tag/x/tx/v0.13.7) - 2024-12-16
+## [v0.13.8](https://github.com/cosmos/cosmos-sdk/releases/tag/x/tx/v0.13.8) - 2025-01-28
 
-### Bug Fixes
+* [#23513](https://github.com/cosmos/cosmos-sdk/pull/23513), [#23539](https://github.com/cosmos/cosmos-sdk/pull/23539) Add map marshalling support (as option) to Amino JSON encoder. 
+
+## [v0.13.7](https://github.com/cosmos/cosmos-sdk/releases/tag/x/tx/v0.13.7) - 2024-12-16
 
 * Fix [ABS-0043](https://github.com/cosmos/cosmos-sdk/security/advisories/GHSA-8wcc-m6j2-qxvm) Limit recursion depth for unknown field detection
 

x/tx/signing/aminojson/json_marshal.go

@@ -38,6 +38,8 @@ type EncoderOptions struct {
 	// It is useful when using the Amino JSON encoder for non Amino purposes,
 	// such as JSON RPC.
 	AminoNameAsTypeURL bool
+	// MarshalMappings when set will use the Amino JSON encoder to marshal maps.
+	MarshalMappings bool
 	// TypeResolver is used to resolve protobuf message types by TypeURL when marshaling any packed messages.
 	TypeResolver signing.TypeResolver
 	// FileResolver is used to resolve protobuf file descriptors TypeURL when TypeResolver fails.
@@ -57,6 +59,7 @@ type Encoder struct {
 	indent                    string
 	enumsAsString             bool
 	aminoNameAsTypeURL        bool
+	marshalMappings           bool
 }
 
 // NewEncoder returns a new Encoder capable of serializing protobuf messages to JSON using the Amino JSON encoding
@@ -93,6 +96,7 @@ func NewEncoder(options EncoderOptions) Encoder {
 		indent:             options.Indent,
 		enumsAsString:      options.EnumAsString,
 		aminoNameAsTypeURL: options.AminoNameAsTypeURL,
+		marshalMappings:    options.MarshalMappings,
 	}
 	return enc
 }
@@ -237,6 +241,20 @@ func (enc Encoder) marshal(value protoreflect.Value, fd protoreflect.FieldDescri
 		return err
 
 	case protoreflect.Map:
+		if enc.marshalMappings {
+			if !val.IsValid() {
+				_, err := io.WriteString(writer, "null")
+				return err
+			}
+
+			mapData := make(map[string]interface{})
+			val.Range(func(k protoreflect.MapKey, v protoreflect.Value) bool {
+				mapData[k.String()] = v.Interface()
+				return true
+			})
+
+			return jsonMarshal(writer, mapData)
+		}
 		return errors.New("maps are not supported")
 
 	case protoreflect.List:

x/tx/signing/aminojson/json_marshal_test.go

@@ -265,7 +265,6 @@ func TestIndent(t *testing.T) {
 
 	bz, err := encoder.Marshal(msg)
 	require.NoError(t, err)
-	fmt.Println(string(bz))
 	require.Equal(t, `{
 	"type": "ABitOfEverything",
 	"value": {
@@ -324,7 +323,6 @@ func TestEnumAsString(t *testing.T) {
 
 	bz, err := encoder.Marshal(msg)
 	require.NoError(t, err)
-	fmt.Println(string(bz))
 	require.Equal(t, `{
 	"type": "ABitOfEverything",
 	"value": {
@@ -383,7 +381,6 @@ func TestAminoNameAsTypeURL(t *testing.T) {
 
 	bz, err := encoder.Marshal(msg)
 	require.NoError(t, err)
-	fmt.Println(string(bz))
 	require.Equal(t, `{
 	"type": "/testpb.ABitOfEverything",
 	"value": {
@@ -414,3 +411,29 @@ func TestAminoNameAsTypeURL(t *testing.T) {
 	}
 }`, string(bz))
 }
+
+func TestMarshalMappings(t *testing.T) {
+	// valid
+	encoder := aminojson.NewEncoder(aminojson.EncoderOptions{Indent: "	", MarshalMappings: true})
+
+	msg := &testpb.WithAMap{
+		StrMap: map[string]string{
+			"foo": "bar",
+			"baz": "qux",
+		},
+	}
+
+	bz, err := encoder.Marshal(msg)
+	require.NoError(t, err)
+	require.Equal(t, `{
+	"str_map": {
+		"baz": "qux",
+		"foo": "bar"
+	}
+}`, string(bz))
+
+	// invalid
+	encoder = aminojson.NewEncoder(aminojson.EncoderOptions{Indent: "	", MarshalMappings: false})
+	_, err = encoder.Marshal(msg)
+	require.Error(t, err)
+}