fix: #2684 (#2693)

core/mapping/unmarshaler.go

@@ -80,438 +80,22 @@ func (u *Unmarshaler) UnmarshalValuer(m Valuer, v interface{}) error {
 	return u.unmarshalWithFullName(simpleValuer{current: m}, v, "")
 }
 
-func (u *Unmarshaler) unmarshalWithFullName(m valuerWithParent, v interface{}, fullName string) error {
-	rv := reflect.ValueOf(v)
-	if err := ValidatePtr(&rv); err != nil {
-		return err
-	}
-
-	rte := reflect.TypeOf(v).Elem()
-	if rte.Kind() != reflect.Struct {
-		return errValueNotStruct
-	}
-
-	rve := rv.Elem()
-	numFields := rte.NumField()
-	for i := 0; i < numFields; i++ {
-		if err := u.processField(rte.Field(i), rve.Field(i), m, fullName); err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-func (u *Unmarshaler) processAnonymousField(field reflect.StructField, value reflect.Value,
-	m valuerWithParent, fullName string) error {
-	key, options, err := u.parseOptionsWithContext(field, m, fullName)
-	if err != nil {
-		return err
-	}
-
-	if _, hasValue := getValue(m, key); hasValue {
-		return fmt.Errorf("fields of %s can't be wrapped inside, because it's anonymous", key)
-	}
-
-	if options.optional() {
-		return u.processAnonymousFieldOptional(field, value, key, m, fullName)
-	}
-
-	return u.processAnonymousFieldRequired(field, value, m, fullName)
-}
-
-func (u *Unmarshaler) processAnonymousFieldOptional(field reflect.StructField, value reflect.Value,
-	key string, m valuerWithParent, fullName string) error {
-	var filled bool
-	var required int
-	var requiredFilled int
-	var indirectValue reflect.Value
-	fieldType := Deref(field.Type)
-
-	for i := 0; i < fieldType.NumField(); i++ {
-		subField := fieldType.Field(i)
-		fieldKey, fieldOpts, err := u.parseOptionsWithContext(subField, m, fullName)
-		if err != nil {
-			return err
-		}
-
-		_, hasValue := getValue(m, fieldKey)
-		if hasValue {
-			if !filled {
-				filled = true
-				maybeNewValue(field, value)
-				indirectValue = reflect.Indirect(value)
-			}
-			if err = u.processField(subField, indirectValue.Field(i), m, fullName); err != nil {
-				return err
-			}
-		}
-		if !fieldOpts.optional() {
-			required++
-			if hasValue {
-				requiredFilled++
-			}
-		}
-	}
-
-	if filled && required != requiredFilled {
-		return fmt.Errorf("%s is not fully set", key)
-	}
-
-	return nil
-}
-
-func (u *Unmarshaler) processAnonymousFieldRequired(field reflect.StructField, value reflect.Value,
-	m valuerWithParent, fullName string) error {
-	maybeNewValue(field, value)
-	fieldType := Deref(field.Type)
-	indirectValue := reflect.Indirect(value)
-
-	for i := 0; i < fieldType.NumField(); i++ {
-		if err := u.processField(fieldType.Field(i), indirectValue.Field(i), m, fullName); err != nil {
-			return err
-		}
-	}
-
-	return nil
-}
-
-func (u *Unmarshaler) processField(field reflect.StructField, value reflect.Value,
-	m valuerWithParent, fullName string) error {
-	if usingDifferentKeys(u.key, field) {
-		return nil
-	}
-
-	if field.Anonymous {
-		return u.processAnonymousField(field, value, m, fullName)
-	}
-
-	return u.processNamedField(field, value, m, fullName)
-}
-
-func (u *Unmarshaler) processFieldNotFromString(field reflect.StructField, value reflect.Value,
-	vp valueWithParent, opts *fieldOptionsWithContext, fullName string) error {
-	fieldType := field.Type
-	derefedFieldType := Deref(fieldType)
-	typeKind := derefedFieldType.Kind()
-	valueKind := reflect.TypeOf(vp.value).Kind()
-	mapValue := vp.value
-
-	switch {
-	case valueKind == reflect.Map && typeKind == reflect.Struct:
-		if mv, ok := mapValue.(map[string]interface{}); ok {
-			return u.processFieldStruct(field, value, &simpleValuer{
-				current: mapValuer(mv),
-				parent:  vp.parent,
-			}, fullName)
-		} else {
-			return errTypeMismatch
-		}
-	case valueKind == reflect.Map && typeKind == reflect.Map:
-		return u.fillMap(field, value, mapValue)
-	case valueKind == reflect.String && typeKind == reflect.Map:
-		return u.fillMapFromString(value, mapValue)
-	case valueKind == reflect.String && typeKind == reflect.Slice:
-		return u.fillSliceFromString(fieldType, value, mapValue)
-	case valueKind == reflect.String && derefedFieldType == durationType:
-		return fillDurationValue(fieldType.Kind(), value, mapValue.(string))
-	default:
-		return u.processFieldPrimitive(field, value, mapValue, opts, fullName)
-	}
-}
-
-func (u *Unmarshaler) processFieldPrimitive(field reflect.StructField, value reflect.Value,
-	mapValue interface{}, opts *fieldOptionsWithContext, fullName string) error {
-	fieldType := field.Type
-	typeKind := Deref(fieldType).Kind()
-	valueKind := reflect.TypeOf(mapValue).Kind()
-
-	switch {
-	case typeKind == reflect.Slice && valueKind == reflect.Slice:
-		return u.fillSlice(fieldType, value, mapValue)
-	case typeKind == reflect.Map && valueKind == reflect.Map:
-		return u.fillMap(field, value, mapValue)
-	default:
-		switch v := mapValue.(type) {
-		case json.Number:
-			return u.processFieldPrimitiveWithJSONNumber(field, value, v, opts, fullName)
-		default:
-			if typeKind == valueKind {
-				if err := validateValueInOptions(mapValue, opts.options()); err != nil {
-					return err
-				}
-
-				return fillWithSameType(field, value, mapValue, opts)
-			}
-		}
-	}
-
-	return newTypeMismatchError(fullName)
-}
-
-func (u *Unmarshaler) processFieldPrimitiveWithJSONNumber(field reflect.StructField, value reflect.Value,
-	v json.Number, opts *fieldOptionsWithContext, fullName string) error {
-	fieldType := field.Type
-	fieldKind := fieldType.Kind()
-	typeKind := Deref(fieldType).Kind()
-
-	if err := validateJsonNumberRange(v, opts); err != nil {
-		return err
-	}
-
-	if err := validateValueInOptions(v, opts.options()); err != nil {
-		return err
-	}
-
-	if fieldKind == reflect.Ptr {
-		value = value.Elem()
-	}
-
-	switch typeKind {
-	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
-		iValue, err := v.Int64()
-		if err != nil {
-			return err
-		}
-
-		value.SetInt(iValue)
-	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
-		iValue, err := v.Int64()
-		if err != nil {
-			return err
-		}
-
-		if iValue < 0 {
-			return fmt.Errorf("unmarshal %q with bad value %q", fullName, v.String())
-		}
-
-		value.SetUint(uint64(iValue))
-	case reflect.Float32, reflect.Float64:
-		fValue, err := v.Float64()
-		if err != nil {
-			return err
-		}
-
-		value.SetFloat(fValue)
-	default:
-		return newTypeMismatchError(fullName)
-	}
-
-	return nil
-}
-
-func (u *Unmarshaler) processFieldStruct(field reflect.StructField, value reflect.Value,
-	m valuerWithParent, fullName string) error {
-	if field.Type.Kind() == reflect.Ptr {
-		baseType := Deref(field.Type)
-		target := reflect.New(baseType).Elem()
-		if err := u.unmarshalWithFullName(m, target.Addr().Interface(), fullName); err != nil {
-			return err
-		}
-
-		value.Set(target.Addr())
-	} else if err := u.unmarshalWithFullName(m, value.Addr().Interface(), fullName); err != nil {
-		return err
-	}
-
-	return nil
-}
-
-func (u *Unmarshaler) processFieldTextUnmarshaler(field reflect.StructField, value reflect.Value,
-	mapValue interface{}) (bool, error) {
-	var tval encoding.TextUnmarshaler
-	var ok bool
-
-	if field.Type.Kind() == reflect.Ptr {
-		tval, ok = value.Interface().(encoding.TextUnmarshaler)
-	} else {
-		tval, ok = value.Addr().Interface().(encoding.TextUnmarshaler)
-	}
-	if ok {
-		switch mv := mapValue.(type) {
-		case string:
-			return true, tval.UnmarshalText([]byte(mv))
-		case []byte:
-			return true, tval.UnmarshalText(mv)
-		}
-	}
-
-	return false, nil
-}
-
-func (u *Unmarshaler) processFieldWithEnvValue(field reflect.StructField, value reflect.Value,
-	envVal string, opts *fieldOptionsWithContext, fullName string) error {
-	if err := validateValueInOptions(envVal, opts.options()); err != nil {
-		return err
-	}
-
-	fieldKind := field.Type.Kind()
-	switch fieldKind {
-	case reflect.Bool:
-		val, err := strconv.ParseBool(envVal)
-		if err != nil {
-			return fmt.Errorf("unmarshal field %q with environment variable, %w", fullName, err)
-		}
-
-		value.SetBool(val)
-		return nil
-	case durationType.Kind():
-		if err := fillDurationValue(fieldKind, value, envVal); err != nil {
-			return fmt.Errorf("unmarshal field %q with environment variable, %w", fullName, err)
-		}
-
-		return nil
-	case reflect.String:
-		value.SetString(envVal)
-		return nil
-	default:
-		return u.processFieldPrimitiveWithJSONNumber(field, value, json.Number(envVal), opts, fullName)
-	}
-}
-
-func (u *Unmarshaler) processNamedField(field reflect.StructField, value reflect.Value,
-	m valuerWithParent, fullName string) error {
-	key, opts, err := u.parseOptionsWithContext(field, m, fullName)
-	if err != nil {
-		return err
-	}
-
-	fullName = join(fullName, key)
-	if opts != nil && len(opts.EnvVar) > 0 {
-		envVal := proc.Env(opts.EnvVar)
-		if len(envVal) > 0 {
-			return u.processFieldWithEnvValue(field, value, envVal, opts, fullName)
-		}
-	}
-
-	canonicalKey := key
-	if u.opts.canonicalKey != nil {
-		canonicalKey = u.opts.canonicalKey(key)
-	}
-
-	valuer := createValuer(m, opts)
-	mapValue, hasValue := getValue(valuer, canonicalKey)
-	if !hasValue {
-		return u.processNamedFieldWithoutValue(field, value, opts, fullName)
-	}
-
-	return u.processNamedFieldWithValue(field, value, valueWithParent{
-		value:  mapValue,
-		parent: valuer,
-	}, key, opts, fullName)
-}
-
-func (u *Unmarshaler) processNamedFieldWithValue(field reflect.StructField, value reflect.Value,
-	vp valueWithParent, key string, opts *fieldOptionsWithContext, fullName string) error {
-	mapValue := vp.value
-	if mapValue == nil {
-		if opts.optional() {
-			return nil
-		}
-
-		return fmt.Errorf("field %s mustn't be nil", key)
-	}
-
-	if !value.CanSet() {
-		return fmt.Errorf("field %s is not settable", key)
-	}
-
-	maybeNewValue(field, value)
-
-	if yes, err := u.processFieldTextUnmarshaler(field, value, mapValue); yes {
-		return err
-	}
-
-	fieldKind := Deref(field.Type).Kind()
-	switch fieldKind {
-	case reflect.Array, reflect.Map, reflect.Slice, reflect.Struct:
-		return u.processFieldNotFromString(field, value, vp, opts, fullName)
-	default:
-		if u.opts.fromString || opts.fromString() {
-			valueKind := reflect.TypeOf(mapValue).Kind()
-			if valueKind != reflect.String {
-				return fmt.Errorf("error: the value in map is not string, but %s", valueKind)
-			}
-
-			options := opts.options()
-			if len(options) > 0 {
-				if !stringx.Contains(options, mapValue.(string)) {
-					return fmt.Errorf(`error: value "%s" for field "%s" is not defined in options "%v"`,
-						mapValue, key, options)
-				}
-			}
-
-			return fillPrimitive(field.Type, value, mapValue, opts, fullName)
-		}
-
-		return u.processFieldNotFromString(field, value, vp, opts, fullName)
-	}
-}
-
-func (u *Unmarshaler) processNamedFieldWithoutValue(field reflect.StructField, value reflect.Value,
-	opts *fieldOptionsWithContext, fullName string) error {
-	derefedType := Deref(field.Type)
-	fieldKind := derefedType.Kind()
-	if defaultValue, ok := opts.getDefault(); ok {
-		if field.Type.Kind() == reflect.Ptr {
-			maybeNewValue(field, value)
-			value = value.Elem()
-		}
-		if derefedType == durationType {
-			return fillDurationValue(fieldKind, value, defaultValue)
-		}
-
-		switch fieldKind {
-		case reflect.Array, reflect.Slice:
-			return u.fillSliceWithDefault(derefedType, value, defaultValue)
-		default:
-			return setValue(fieldKind, value, defaultValue)
-		}
-	}
-
-	switch fieldKind {
-	case reflect.Array, reflect.Map, reflect.Slice:
-		if !opts.optional() {
-			return u.processFieldNotFromString(field, value, valueWithParent{
-				value: emptyMap,
-			}, opts, fullName)
-		}
-	case reflect.Struct:
-		if !opts.optional() {
-			required, err := structValueRequired(u.key, derefedType)
-			if err != nil {
-				return err
-			}
-
-			if required {
-				return fmt.Errorf("%q is not set", fullName)
-			}
-
-			return u.processFieldNotFromString(field, value, valueWithParent{
-				value: emptyMap,
-			}, opts, fullName)
-		}
-	default:
-		if !opts.optional() {
-			return newInitError(fullName)
-		}
-	}
-
-	return nil
-}
-
-func (u *Unmarshaler) fillMap(field reflect.StructField, value reflect.Value, mapValue interface{}) error {
+func (u *Unmarshaler) fillMap(fieldType reflect.Type, value reflect.Value, mapValue interface{}) error {
 	if !value.CanSet() {
 		return errValueNotSettable
 	}
 
-	fieldKeyType := field.Type.Key()
-	fieldElemType := field.Type.Elem()
+	fieldKeyType := fieldType.Key()
+	fieldElemType := fieldType.Elem()
 	targetValue, err := u.generateMap(fieldKeyType, fieldElemType, mapValue)
 	if err != nil {
 		return err
 	}
 
+	if !targetValue.Type().AssignableTo(value.Type()) {
+		return errTypeMismatch
+	}
+
 	value.Set(targetValue)
 	return nil
 }
@@ -633,12 +217,14 @@ func (u *Unmarshaler) fillSliceValue(slice reflect.Value, index int,
 		return setValue(baseKind, ithVal, v.String())
 	case string:
 		return setValue(baseKind, ithVal, v)
+	case map[string]interface{}:
+		return u.fillMap(ithVal.Type(), ithVal, value)
 	default:
 		// don't need to consider the difference between int, int8, int16, int32, int64,
 		// uint, uint8, uint16, uint32, uint64, because they're handled as json.Number.
 		if ithVal.Kind() == reflect.Ptr {
 			baseType := Deref(ithVal.Type())
-			if baseType.Kind() != reflect.TypeOf(value).Kind() {
+			if !reflect.TypeOf(value).AssignableTo(baseType) {
 				return errTypeMismatch
 			}
 
@@ -648,7 +234,7 @@ func (u *Unmarshaler) fillSliceValue(slice reflect.Value, index int,
 			return nil
 		}
 
-		if ithVal.Kind() != reflect.TypeOf(value).Kind() {
+		if !reflect.TypeOf(value).AssignableTo(ithVal.Type()) {
 			return errTypeMismatch
 		}
 
@@ -783,6 +369,424 @@ func (u *Unmarshaler) parseOptionsWithContext(field reflect.StructField, m Value
 	return key, optsWithContext, nil
 }
 
+func (u *Unmarshaler) processAnonymousField(field reflect.StructField, value reflect.Value,
+	m valuerWithParent, fullName string) error {
+	key, options, err := u.parseOptionsWithContext(field, m, fullName)
+	if err != nil {
+		return err
+	}
+
+	if _, hasValue := getValue(m, key); hasValue {
+		return fmt.Errorf("fields of %s can't be wrapped inside, because it's anonymous", key)
+	}
+
+	if options.optional() {
+		return u.processAnonymousFieldOptional(field.Type, value, key, m, fullName)
+	}
+
+	return u.processAnonymousFieldRequired(field.Type, value, m, fullName)
+}
+
+func (u *Unmarshaler) processAnonymousFieldOptional(fieldType reflect.Type, value reflect.Value,
+	key string, m valuerWithParent, fullName string) error {
+	var filled bool
+	var required int
+	var requiredFilled int
+	var indirectValue reflect.Value
+	derefedFieldType := Deref(fieldType)
+
+	for i := 0; i < derefedFieldType.NumField(); i++ {
+		subField := derefedFieldType.Field(i)
+		fieldKey, fieldOpts, err := u.parseOptionsWithContext(subField, m, fullName)
+		if err != nil {
+			return err
+		}
+
+		_, hasValue := getValue(m, fieldKey)
+		if hasValue {
+			if !filled {
+				filled = true
+				maybeNewValue(fieldType, value)
+				indirectValue = reflect.Indirect(value)
+			}
+			if err = u.processField(subField, indirectValue.Field(i), m, fullName); err != nil {
+				return err
+			}
+		}
+		if !fieldOpts.optional() {
+			required++
+			if hasValue {
+				requiredFilled++
+			}
+		}
+	}
+
+	if filled && required != requiredFilled {
+		return fmt.Errorf("%s is not fully set", key)
+	}
+
+	return nil
+}
+
+func (u *Unmarshaler) processAnonymousFieldRequired(fieldType reflect.Type, value reflect.Value,
+	m valuerWithParent, fullName string) error {
+	maybeNewValue(fieldType, value)
+	derefedFieldType := Deref(fieldType)
+	indirectValue := reflect.Indirect(value)
+
+	for i := 0; i < derefedFieldType.NumField(); i++ {
+		if err := u.processField(derefedFieldType.Field(i), indirectValue.Field(i), m, fullName); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (u *Unmarshaler) processField(field reflect.StructField, value reflect.Value,
+	m valuerWithParent, fullName string) error {
+	if usingDifferentKeys(u.key, field) {
+		return nil
+	}
+
+	if field.Anonymous {
+		return u.processAnonymousField(field, value, m, fullName)
+	}
+
+	return u.processNamedField(field, value, m, fullName)
+}
+
+func (u *Unmarshaler) processFieldNotFromString(fieldType reflect.Type, value reflect.Value,
+	vp valueWithParent, opts *fieldOptionsWithContext, fullName string) error {
+	derefedFieldType := Deref(fieldType)
+	typeKind := derefedFieldType.Kind()
+	valueKind := reflect.TypeOf(vp.value).Kind()
+	mapValue := vp.value
+
+	switch {
+	case valueKind == reflect.Map && typeKind == reflect.Struct:
+		mv, ok := mapValue.(map[string]interface{})
+		if !ok {
+			return errTypeMismatch
+		}
+
+		return u.processFieldStruct(fieldType, value, &simpleValuer{
+			current: mapValuer(mv),
+			parent:  vp.parent,
+		}, fullName)
+	case valueKind == reflect.Map && typeKind == reflect.Map:
+		return u.fillMap(fieldType, value, mapValue)
+	case valueKind == reflect.String && typeKind == reflect.Map:
+		return u.fillMapFromString(value, mapValue)
+	case valueKind == reflect.String && typeKind == reflect.Slice:
+		return u.fillSliceFromString(fieldType, value, mapValue)
+	case valueKind == reflect.String && derefedFieldType == durationType:
+		return fillDurationValue(fieldType.Kind(), value, mapValue.(string))
+	default:
+		return u.processFieldPrimitive(fieldType, value, mapValue, opts, fullName)
+	}
+}
+
+func (u *Unmarshaler) processFieldPrimitive(fieldType reflect.Type, value reflect.Value,
+	mapValue interface{}, opts *fieldOptionsWithContext, fullName string) error {
+	typeKind := Deref(fieldType).Kind()
+	valueKind := reflect.TypeOf(mapValue).Kind()
+
+	switch {
+	case typeKind == reflect.Slice && valueKind == reflect.Slice:
+		return u.fillSlice(fieldType, value, mapValue)
+	case typeKind == reflect.Map && valueKind == reflect.Map:
+		return u.fillMap(fieldType, value, mapValue)
+	default:
+		switch v := mapValue.(type) {
+		case json.Number:
+			return u.processFieldPrimitiveWithJSONNumber(fieldType, value, v, opts, fullName)
+		default:
+			if typeKind == valueKind {
+				if err := validateValueInOptions(mapValue, opts.options()); err != nil {
+					return err
+				}
+
+				return fillWithSameType(fieldType, value, mapValue, opts)
+			}
+		}
+	}
+
+	return newTypeMismatchError(fullName)
+}
+
+func (u *Unmarshaler) processFieldPrimitiveWithJSONNumber(fieldType reflect.Type, value reflect.Value,
+	v json.Number, opts *fieldOptionsWithContext, fullName string) error {
+	fieldKind := fieldType.Kind()
+	typeKind := Deref(fieldType).Kind()
+
+	if err := validateJsonNumberRange(v, opts); err != nil {
+		return err
+	}
+
+	if err := validateValueInOptions(v, opts.options()); err != nil {
+		return err
+	}
+
+	if fieldKind == reflect.Ptr {
+		value = value.Elem()
+	}
+
+	switch typeKind {
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
+		iValue, err := v.Int64()
+		if err != nil {
+			return err
+		}
+
+		value.SetInt(iValue)
+	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		iValue, err := v.Int64()
+		if err != nil {
+			return err
+		}
+
+		if iValue < 0 {
+			return fmt.Errorf("unmarshal %q with bad value %q", fullName, v.String())
+		}
+
+		value.SetUint(uint64(iValue))
+	case reflect.Float32, reflect.Float64:
+		fValue, err := v.Float64()
+		if err != nil {
+			return err
+		}
+
+		value.SetFloat(fValue)
+	default:
+		return newTypeMismatchError(fullName)
+	}
+
+	return nil
+}
+
+func (u *Unmarshaler) processFieldStruct(fieldType reflect.Type, value reflect.Value,
+	m valuerWithParent, fullName string) error {
+	if fieldType.Kind() == reflect.Ptr {
+		baseType := Deref(fieldType)
+		target := reflect.New(baseType).Elem()
+		if err := u.unmarshalWithFullName(m, target.Addr().Interface(), fullName); err != nil {
+			return err
+		}
+
+		value.Set(target.Addr())
+	} else if err := u.unmarshalWithFullName(m, value.Addr().Interface(), fullName); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func (u *Unmarshaler) processFieldTextUnmarshaler(fieldType reflect.Type, value reflect.Value,
+	mapValue interface{}) (bool, error) {
+	var tval encoding.TextUnmarshaler
+	var ok bool
+
+	if fieldType.Kind() == reflect.Ptr {
+		tval, ok = value.Interface().(encoding.TextUnmarshaler)
+	} else {
+		tval, ok = value.Addr().Interface().(encoding.TextUnmarshaler)
+	}
+	if ok {
+		switch mv := mapValue.(type) {
+		case string:
+			return true, tval.UnmarshalText([]byte(mv))
+		case []byte:
+			return true, tval.UnmarshalText(mv)
+		}
+	}
+
+	return false, nil
+}
+
+func (u *Unmarshaler) processFieldWithEnvValue(fieldType reflect.Type, value reflect.Value,
+	envVal string, opts *fieldOptionsWithContext, fullName string) error {
+	if err := validateValueInOptions(envVal, opts.options()); err != nil {
+		return err
+	}
+
+	fieldKind := fieldType.Kind()
+	switch fieldKind {
+	case reflect.Bool:
+		val, err := strconv.ParseBool(envVal)
+		if err != nil {
+			return fmt.Errorf("unmarshal field %q with environment variable, %w", fullName, err)
+		}
+
+		value.SetBool(val)
+		return nil
+	case durationType.Kind():
+		if err := fillDurationValue(fieldKind, value, envVal); err != nil {
+			return fmt.Errorf("unmarshal field %q with environment variable, %w", fullName, err)
+		}
+
+		return nil
+	case reflect.String:
+		value.SetString(envVal)
+		return nil
+	default:
+		return u.processFieldPrimitiveWithJSONNumber(fieldType, value, json.Number(envVal), opts, fullName)
+	}
+}
+
+func (u *Unmarshaler) processNamedField(field reflect.StructField, value reflect.Value,
+	m valuerWithParent, fullName string) error {
+	key, opts, err := u.parseOptionsWithContext(field, m, fullName)
+	if err != nil {
+		return err
+	}
+
+	fullName = join(fullName, key)
+	if opts != nil && len(opts.EnvVar) > 0 {
+		envVal := proc.Env(opts.EnvVar)
+		if len(envVal) > 0 {
+			return u.processFieldWithEnvValue(field.Type, value, envVal, opts, fullName)
+		}
+	}
+
+	canonicalKey := key
+	if u.opts.canonicalKey != nil {
+		canonicalKey = u.opts.canonicalKey(key)
+	}
+
+	valuer := createValuer(m, opts)
+	mapValue, hasValue := getValue(valuer, canonicalKey)
+	if !hasValue {
+		return u.processNamedFieldWithoutValue(field.Type, value, opts, fullName)
+	}
+
+	return u.processNamedFieldWithValue(field.Type, value, valueWithParent{
+		value:  mapValue,
+		parent: valuer,
+	}, key, opts, fullName)
+}
+
+func (u *Unmarshaler) processNamedFieldWithValue(fieldType reflect.Type, value reflect.Value,
+	vp valueWithParent, key string, opts *fieldOptionsWithContext, fullName string) error {
+	mapValue := vp.value
+	if mapValue == nil {
+		if opts.optional() {
+			return nil
+		}
+
+		return fmt.Errorf("field %s mustn't be nil", key)
+	}
+
+	if !value.CanSet() {
+		return fmt.Errorf("field %s is not settable", key)
+	}
+
+	maybeNewValue(fieldType, value)
+
+	if yes, err := u.processFieldTextUnmarshaler(fieldType, value, mapValue); yes {
+		return err
+	}
+
+	fieldKind := Deref(fieldType).Kind()
+	switch fieldKind {
+	case reflect.Array, reflect.Map, reflect.Slice, reflect.Struct:
+		return u.processFieldNotFromString(fieldType, value, vp, opts, fullName)
+	default:
+		if u.opts.fromString || opts.fromString() {
+			valueKind := reflect.TypeOf(mapValue).Kind()
+			if valueKind != reflect.String {
+				return fmt.Errorf("error: the value in map is not string, but %s", valueKind)
+			}
+
+			options := opts.options()
+			if len(options) > 0 {
+				if !stringx.Contains(options, mapValue.(string)) {
+					return fmt.Errorf(`error: value "%s" for field "%s" is not defined in options "%v"`,
+						mapValue, key, options)
+				}
+			}
+
+			return fillPrimitive(fieldType, value, mapValue, opts, fullName)
+		}
+
+		return u.processFieldNotFromString(fieldType, value, vp, opts, fullName)
+	}
+}
+
+func (u *Unmarshaler) processNamedFieldWithoutValue(fieldType reflect.Type, value reflect.Value,
+	opts *fieldOptionsWithContext, fullName string) error {
+	derefedType := Deref(fieldType)
+	fieldKind := derefedType.Kind()
+	if defaultValue, ok := opts.getDefault(); ok {
+		if fieldType.Kind() == reflect.Ptr {
+			maybeNewValue(fieldType, value)
+			value = value.Elem()
+		}
+		if derefedType == durationType {
+			return fillDurationValue(fieldKind, value, defaultValue)
+		}
+
+		switch fieldKind {
+		case reflect.Array, reflect.Slice:
+			return u.fillSliceWithDefault(derefedType, value, defaultValue)
+		default:
+			return setValue(fieldKind, value, defaultValue)
+		}
+	}
+
+	switch fieldKind {
+	case reflect.Array, reflect.Map, reflect.Slice:
+		if !opts.optional() {
+			return u.processFieldNotFromString(fieldType, value, valueWithParent{
+				value: emptyMap,
+			}, opts, fullName)
+		}
+	case reflect.Struct:
+		if !opts.optional() {
+			required, err := structValueRequired(u.key, derefedType)
+			if err != nil {
+				return err
+			}
+
+			if required {
+				return fmt.Errorf("%q is not set", fullName)
+			}
+
+			return u.processFieldNotFromString(fieldType, value, valueWithParent{
+				value: emptyMap,
+			}, opts, fullName)
+		}
+	default:
+		if !opts.optional() {
+			return newInitError(fullName)
+		}
+	}
+
+	return nil
+}
+
+func (u *Unmarshaler) unmarshalWithFullName(m valuerWithParent, v interface{}, fullName string) error {
+	rv := reflect.ValueOf(v)
+	if err := ValidatePtr(&rv); err != nil {
+		return err
+	}
+
+	rte := reflect.TypeOf(v).Elem()
+	if rte.Kind() != reflect.Struct {
+		return errValueNotStruct
+	}
+
+	rve := rv.Elem()
+	numFields := rte.NumField()
+	for i := 0; i < numFields; i++ {
+		if err := u.processField(rte.Field(i), rve.Field(i), m, fullName); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
 // WithStringValues customizes an Unmarshaler with number values from strings.
 func WithStringValues() UnmarshalOption {
 	return func(opt *unmarshalOptions) {
@@ -855,7 +859,7 @@ func fillPrimitive(fieldType reflect.Type, value reflect.Value, mapValue interfa
 	}
 }
 
-func fillWithSameType(field reflect.StructField, value reflect.Value, mapValue interface{},
+func fillWithSameType(fieldType reflect.Type, value reflect.Value, mapValue interface{},
 	opts *fieldOptionsWithContext) error {
 	if !value.CanSet() {
 		return errValueNotSettable
@@ -865,13 +869,13 @@ func fillWithSameType(field reflect.StructField, value reflect.Value, mapValue i
 		return err
 	}
 
-	if field.Type.Kind() == reflect.Ptr {
-		baseType := Deref(field.Type)
+	if fieldType.Kind() == reflect.Ptr {
+		baseType := Deref(fieldType)
 		target := reflect.New(baseType).Elem()
 		setSameKindValue(baseType, target, mapValue)
 		value.Set(target.Addr())
 	} else {
-		setSameKindValue(field.Type, value, mapValue)
+		setSameKindValue(fieldType, value, mapValue)
 	}
 
 	return nil

core/mapping/unmarshaler_test.go

@@ -3628,6 +3628,54 @@ func TestUnmarshalJsonReaderWithMismatchTypeBoolMap(t *testing.T) {
 	}, &req))
 }
 
+func TestUnmarshalJsonBytesSliceOfMaps(t *testing.T) {
+	input := []byte(`{
+  "order_id": "1234567",
+  "refund_reason": {
+    "reason_code": [
+      123,
+      234
+    ],
+    "desc": "not wanted",
+    "show_reason": [
+      {
+        "123": "not enough",
+        "234": "closed"
+      }
+    ]
+  },
+  "product_detail": {
+    "product_id": "123",
+    "sku_id": "123",
+    "name": "cake",
+    "actual_amount": 100
+  }
+}`)
+
+	type (
+		RefundReasonData struct {
+			ReasonCode []int               `json:"reason_code"`
+			Desc       string              `json:"desc"`
+			ShowReason []map[string]string `json:"show_reason"`
+		}
+
+		ProductDetailData struct {
+			ProductId    string `json:"product_id"`
+			SkuId        string `json:"sku_id"`
+			Name         string `json:"name"`
+			ActualAmount int    `json:"actual_amount"`
+		}
+		OrderApplyRefundReq struct {
+			OrderId       string            `json:"order_id"`
+			RefundReason  RefundReasonData  `json:"refund_reason,optional"`
+			ProductDetail ProductDetailData `json:"product_detail,optional"`
+		}
+	)
+
+	var req OrderApplyRefundReq
+	assert.NoError(t, UnmarshalJsonBytes(input, &req))
+}
+
 func BenchmarkDefaultValue(b *testing.B) {
 	for i := 0; i < b.N; i++ {
 		var a struct {

core/mapping/utils.go

@@ -210,8 +210,8 @@ func isRightInclude(b byte) (bool, error) {
 	}
 }
 
-func maybeNewValue(field reflect.StructField, value reflect.Value) {
-	if field.Type.Kind() == reflect.Ptr && value.IsNil() {
+func maybeNewValue(fieldType reflect.Type, value reflect.Value) {
+	if fieldType.Kind() == reflect.Ptr && value.IsNil() {
 		value.Set(reflect.New(value.Type().Elem()))
 	}
 }