Consider empty slices to be "zero"

serializer/serix/map_encode.go

@@ -198,7 +198,7 @@ func (api *API) mapEncodeStructFields(
 			continue
 		}
 
-		if sField.settings.omitEmpty && fieldValue.IsZero() {
+		if sField.settings.omitEmpty && api.isValueEmpty(fieldValue) {
 			continue
 		}
 
@@ -323,3 +323,19 @@ func (api *API) mapEncodeMap(ctx context.Context, value reflect.Value, ts TypeSe
 
 	return m, nil
 }
+
+// Returns whether the value is empty.
+//
+// Thin wrapper around reflect.Value.IsZero to also consider slices of length 0 as empty.
+func (api *API) isValueEmpty(value reflect.Value) bool {
+	if value.IsZero() {
+		return true
+	}
+
+	switch value.Kind() {
+	case reflect.Slice:
+		return value.Len() == 0
+	}
+
+	return false
+}

serializer/serix/serix_test.go

@@ -3,7 +3,9 @@ package serix_test
 
 import (
 	"context"
+	"encoding/json"
 	"reflect"
+	"strings"
 	"testing"
 
 	"github.com/iancoleman/orderedmap"
@@ -808,3 +810,56 @@ func (test *decodingTest) run(t *testing.T) {
 
 	require.EqualValues(t, test.source, jsonDest)
 }
+
+func TestSerixOmitEmpty(t *testing.T) {
+	type Numbers struct {
+		Bytes []uint8 `serix:",omitempty"`
+	}
+	type omitEmptyTest struct {
+		name        string
+		expectEmpty bool
+		source      Numbers
+	}
+
+	tests := []omitEmptyTest{
+		{
+			name:        "ok - slice empty",
+			expectEmpty: true,
+			source: Numbers{
+				Bytes: []uint8{},
+			},
+		},
+		{
+			name:        "ok - nil slice",
+			expectEmpty: true,
+			source: Numbers{
+				Bytes: nil,
+			},
+		},
+		{
+			name:        "ok - non-empty slice",
+			expectEmpty: false,
+			source: Numbers{
+				Bytes: []uint8{0xff},
+			},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			encodedJson, err := testAPI.JSONEncode(context.Background(), test.source)
+			require.NoError(t, err)
+
+			dec := json.NewDecoder(strings.NewReader(string(encodedJson)))
+			var decoded Numbers
+			err = dec.Decode(&decoded)
+			require.NoError(t, err)
+
+			if test.expectEmpty {
+				require.Empty(t, decoded.Bytes)
+			} else {
+				require.NotEmpty(t, decoded.Bytes)
+			}
+		})
+	}
+}