fix: fix apijson.Port for embedded structs (#3844)

internal/apijson/port.go

@@ -34,22 +34,33 @@ func Port(from any, to any) error {
 	fromJSON := fromVal.FieldByName("JSON")
 	toJSON := toVal.FieldByName("JSON")
 
-	// First, iterate through the from fields and load all the "normal" fields in the struct to the map of
-	// string to reflect.Value, as well as their raw .JSON.Foo counterpart.
-	for i := 0; i < fromType.NumField(); i++ {
-		field := fromType.Field(i)
-		ptag, ok := parseJSONStructTag(field)
-		if !ok {
-			continue
-		}
-		if ptag.name == "-" {
-			continue
+	// Iterate through the fields of v and load all the "normal" fields in the struct to the map of
+	// string to reflect.Value, as well as their raw .JSON.Foo counterpart indicated by j.
+	var getFields func(t reflect.Type, v, j reflect.Value)
+	getFields = func(t reflect.Type, v, j reflect.Value) {
+		// Recurse into anonymous fields first, since the fields on the object should win over the fields in the
+		// embedded object.
+		for i := 0; i < t.NumField(); i++ {
+			field := t.Field(i)
+			if field.Anonymous {
+				getFields(field.Type, v.Field(i), v.FieldByName("JSON"))
+				continue
+			}
 		}
-		values[ptag.name] = fromVal.Field(i)
-		if fromJSON.IsValid() {
-			fields[ptag.name] = fromJSON.FieldByName(field.Name)
+
+		for i := 0; i < t.NumField(); i++ {
+			field := t.Field(i)
+			ptag, ok := parseJSONStructTag(field)
+			if !ok || ptag.name == "-" {
+				continue
+			}
+			values[ptag.name] = v.Field(i)
+			if j.IsValid() {
+				fields[ptag.name] = j.FieldByName(field.Name)
+			}
 		}
 	}
+	getFields(fromType, fromVal, fromJSON)
 
 	// Use the values from the previous step to populate the 'to' struct.
 	for i := 0; i < toType.NumField(); i++ {

internal/apijson/port_test.go

@@ -94,6 +94,37 @@ type CardMastercardData struct {
 	Bar int64 `json:"bar"`
 }
 
+type CommonFields struct {
+	Metadata Metadata `json:"metadata"`
+	Value    string   `json:"value"`
+}
+
+type commonFieldsJSON struct {
+	Metadata    Field
+	Value       Field
+	ExtraFields map[string]Field
+}
+
+type CardEmbedded struct {
+	CommonFields
+	Processor CardVisaProcessor `json:"processor"`
+	Data      CardVisaData      `json:"data"`
+	IsFoo     bool              `json:"is_foo"`
+
+	JSON cardEmbeddedJSON
+}
+
+type cardEmbeddedJSON struct {
+	commonFieldsJSON
+	Processor   Field
+	Data        Field
+	IsFoo       Field
+	ExtraFields map[string]Field
+	raw         string
+}
+
+func (r cardEmbeddedJSON) RawJSON() string { return r.raw }
+
 var portTests = map[string]struct {
 	from any
 	to   any
@@ -158,6 +189,51 @@ var portTests = map[string]struct {
 			Value: false,
 		},
 	},
+	"embedded to card": {
+		CardEmbedded{
+			CommonFields: CommonFields{
+				Metadata: Metadata{
+					CreatedAt: "Mar 29 2024",
+				},
+				Value: "embedded_value",
+			},
+			Processor: "visa",
+			IsFoo:     true,
+			Data: CardVisaData{
+				Foo: "embedded_foo",
+			},
+			JSON: cardEmbeddedJSON{
+				commonFieldsJSON: commonFieldsJSON{
+					Metadata: Field{raw: `{"created_at":"Mar 29 2024"}`, status: valid},
+					Value:    Field{raw: `"embedded_value"`, status: valid},
+				},
+				raw:       `{"processor":"visa","is_foo":true,"data":{"foo":"embedded_foo"}}`,
+				Processor: Field{raw: `"visa"`, status: valid},
+				IsFoo:     Field{raw: `true`, status: valid},
+				Data:      Field{raw: `{"foo":"embedded_foo"}`, status: valid},
+			},
+		},
+		Card{
+			Processor: "visa",
+			IsFoo:     true,
+			IsBar:     false,
+			Data: CardVisaData{
+				Foo: "embedded_foo",
+			},
+			Metadata: Metadata{
+				CreatedAt: "Mar 29 2024",
+			},
+			Value: "embedded_value",
+			JSON: cardJSON{
+				raw:       "{\"processor\":\"visa\",\"is_foo\":true,\"data\":{\"foo\":\"embedded_foo\"}}",
+				Processor: Field{raw: `"visa"`, status: 0x3},
+				IsFoo:     Field{raw: "true", status: 0x3},
+				Data:      Field{raw: `{"foo":"embedded_foo"}`, status: 0x3},
+				Metadata:  Field{raw: `{"created_at":"Mar 29 2024"}`, status: 0x3},
+				Value:     Field{raw: `"embedded_value"`, status: 0x3},
+			},
+		},
+	},
 }
 
 func TestPort(t *testing.T) {