diff --git a/binding/bind.go b/binding/bind.go
index f22ca78..b3c00ea 100644
--- a/binding/bind.go
+++ b/binding/bind.go
@@ -418,3 +418,7 @@ func (b *Binding) bindJSON(pointer interface{}, bodyBytes []byte) error {
 func (b *Binding) ResetJSONUnmarshaler(fn JSONUnmarshaler) {
 	b.jsonUnmarshalFunc = fn
 }
+
+func (b *Binding) ResetValidator(vd *validator.Validator) {
+	b.vd = vd
+}
\ No newline at end of file
diff --git a/go.mod b/go.mod
index 1c25523..ea150e3 100644
--- a/go.mod
+++ b/go.mod
@@ -1,6 +1,8 @@
 module github.com/bytedance/go-tagexpr/v2
 
-go 1.14
+go 1.22
+
+toolchain go1.22.2
 
 require (
 	github.com/andeya/ameda v1.5.3
@@ -10,5 +12,15 @@ require (
 	github.com/stretchr/testify v1.7.5
 	github.com/tidwall/match v1.1.1
 	github.com/tidwall/pretty v1.2.0
-	google.golang.org/protobuf v1.27.1
+	google.golang.org/protobuf v1.36.6
+)
+
+require (
+	github.com/golang/protobuf v1.5.0 // indirect
+	github.com/google/go-cmp v0.5.5 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/stretchr/objx v0.4.0 // indirect
+	golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 // indirect
+	gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )
diff --git a/go.sum b/go.sum
index 79105e4..1aaa1e6 100644
--- a/go.sum
+++ b/go.sum
@@ -28,6 +28,8 @@ golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8T
 google.golang.org/protobuf v1.26.0-rc.1/go.mod h1:jlhhOSvTdKEhbULTjvd4ARK9grFBp09yW+WbY/TyQbw=
 google.golang.org/protobuf v1.27.1 h1:SnqbnDw1V7RiZcXPx5MEeqPv2s79L9i7BJUlG/+RurQ=
 google.golang.org/protobuf v1.27.1/go.mod h1:9q0QmTI4eRPtz6boOQmLYwt+qCgq0jsYwAQnmE0givc=
+google.golang.org/protobuf v1.36.6 h1:z1NpPI8ku2WgiWnf+t9wTPsn6eP1L7ksHUlkfLvd9xY=
+google.golang.org/protobuf v1.36.6/go.mod h1:jduwjTPXsFjZGTmRluh+L6NjiWu7pchiJ2/5YcXBHnY=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/tagexpr.go b/tagexpr.go
index 288f351..1661d15 100644
--- a/tagexpr.go
+++ b/tagexpr.go
@@ -38,10 +38,25 @@ type (
 // VM struct tag expression interpreter
 type VM struct {
 	tagName   string
+	checkPublicOnly bool
 	structJar map[uintptr]*structVM
 	rw        sync.RWMutex
 }
 
+type TagExprOption func(*VM)
+
+func WithTagName(tagName string) TagExprOption {
+	return func(vm *VM) {
+		vm.tagName = tagName
+	}
+}
+
+func WithCheckPublicOnly() TagExprOption {
+	return func(vm *VM) {
+		vm.checkPublicOnly = true
+	}
+}
+
 // structVM tag expression set of struct
 type structVM struct {
 	vm                         *VM
@@ -291,6 +306,9 @@ func (vm *VM) registerStructLocked(structType reflect.Type) (*structVM, error) {
 	var sub *structVM
 	for i := 0; i < numField; i++ {
 		structField = structType.Field(i)
+		if vm.checkPublicOnly && structField.PkgPath != "" {
+			continue	// skip private fields
+		}
 		field, ok, err := s.newFieldVM(structField)
 		if err != nil {
 			s.err = err
diff --git a/test_data/demo.pb.go b/test_data/demo.pb.go
new file mode 100644
index 0000000..bf6bd7d
--- /dev/null
+++ b/test_data/demo.pb.go
@@ -0,0 +1,222 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// versions:
+// 	protoc-gen-go v1.28.0
+// 	protoc        v5.27.1
+// source: demo.proto
+
+package test_data
+
+import (
+	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
+	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
+	reflect "reflect"
+	sync "sync"
+)
+
+const (
+	// Verify that this generated code is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(20 - protoimpl.MinVersion)
+	// Verify that runtime/protoimpl is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
+)
+
+type EchoRequest struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	Msg  string                    `protobuf:"bytes,1,opt,name=msg,proto3" form:"msg" json:"msg,omitempty" vd:"@:len($) >= 3"`
+	Subs []*EchoRequest_SubMessage `protobuf:"bytes,2,rep,name=subs,proto3" form:"subs" json:"subs,omitempty" query:"subs"`
+}
+
+func (x *EchoRequest) Reset() {
+	*x = EchoRequest{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_demo_proto_msgTypes[0]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *EchoRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*EchoRequest) ProtoMessage() {}
+
+func (x *EchoRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_demo_proto_msgTypes[0]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use EchoRequest.ProtoReflect.Descriptor instead.
+func (*EchoRequest) Descriptor() ([]byte, []int) {
+	return file_demo_proto_rawDescGZIP(), []int{0}
+}
+
+func (x *EchoRequest) GetMsg() string {
+	if x != nil {
+		return x.Msg
+	}
+	return ""
+}
+
+func (x *EchoRequest) GetSubs() []*EchoRequest_SubMessage {
+	if x != nil {
+		return x.Subs
+	}
+	return nil
+}
+
+type EchoRequest_SubMessage struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	Msg string `protobuf:"bytes,1,opt,name=msg,proto3" form:"msg" json:"msg,omitempty" query:"msg" vd:"len($) >= 4"`
+}
+
+func (x *EchoRequest_SubMessage) Reset() {
+	*x = EchoRequest_SubMessage{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_demo_proto_msgTypes[1]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *EchoRequest_SubMessage) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*EchoRequest_SubMessage) ProtoMessage() {}
+
+func (x *EchoRequest_SubMessage) ProtoReflect() protoreflect.Message {
+	mi := &file_demo_proto_msgTypes[1]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use EchoRequest_SubMessage.ProtoReflect.Descriptor instead.
+func (*EchoRequest_SubMessage) Descriptor() ([]byte, []int) {
+	return file_demo_proto_rawDescGZIP(), []int{0, 0}
+}
+
+func (x *EchoRequest_SubMessage) GetMsg() string {
+	if x != nil {
+		return x.Msg
+	}
+	return ""
+}
+
+var File_demo_proto protoreflect.FileDescriptor
+
+var file_demo_proto_rawDesc = []byte{
+	0x0a, 0x0a, 0x64, 0x65, 0x6d, 0x6f, 0x2e, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x12, 0x09, 0x74, 0x65,
+	0x73, 0x74, 0x5f, 0x64, 0x61, 0x74, 0x61, 0x1a, 0x09, 0x61, 0x70, 0x69, 0x2e, 0x70, 0x72, 0x6f,
+	0x74, 0x6f, 0x22, 0xa1, 0x01, 0x0a, 0x0b, 0x45, 0x63, 0x68, 0x6f, 0x52, 0x65, 0x71, 0x75, 0x65,
+	0x73, 0x74, 0x12, 0x2a, 0x0a, 0x03, 0x6d, 0x73, 0x67, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09, 0x42,
+	0x18, 0xca, 0xbb, 0x18, 0x03, 0x6d, 0x73, 0x67, 0xda, 0xbb, 0x18, 0x0d, 0x40, 0x3a, 0x6c, 0x65,
+	0x6e, 0x28, 0x24, 0x29, 0x20, 0x3e, 0x3d, 0x20, 0x33, 0x52, 0x03, 0x6d, 0x73, 0x67, 0x12, 0x35,
+	0x0a, 0x04, 0x73, 0x75, 0x62, 0x73, 0x18, 0x02, 0x20, 0x03, 0x28, 0x0b, 0x32, 0x21, 0x2e, 0x74,
+	0x65, 0x73, 0x74, 0x5f, 0x64, 0x61, 0x74, 0x61, 0x2e, 0x45, 0x63, 0x68, 0x6f, 0x52, 0x65, 0x71,
+	0x75, 0x65, 0x73, 0x74, 0x2e, 0x53, 0x75, 0x62, 0x4d, 0x65, 0x73, 0x73, 0x61, 0x67, 0x65, 0x52,
+	0x04, 0x73, 0x75, 0x62, 0x73, 0x1a, 0x2f, 0x0a, 0x0a, 0x53, 0x75, 0x62, 0x4d, 0x65, 0x73, 0x73,
+	0x61, 0x67, 0x65, 0x12, 0x21, 0x0a, 0x03, 0x6d, 0x73, 0x67, 0x18, 0x01, 0x20, 0x01, 0x28, 0x09,
+	0x42, 0x0f, 0xda, 0xbb, 0x18, 0x0b, 0x6c, 0x65, 0x6e, 0x28, 0x24, 0x29, 0x20, 0x3e, 0x3d, 0x20,
+	0x34, 0x52, 0x03, 0x6d, 0x73, 0x67, 0x42, 0x2e, 0x5a, 0x2c, 0x67, 0x69, 0x74, 0x68, 0x75, 0x62,
+	0x2e, 0x63, 0x6f, 0x6d, 0x2f, 0x62, 0x79, 0x74, 0x65, 0x64, 0x61, 0x6e, 0x63, 0x65, 0x2f, 0x67,
+	0x6f, 0x2d, 0x74, 0x61, 0x67, 0x65, 0x78, 0x70, 0x72, 0x2f, 0x76, 0x32, 0x2f, 0x74, 0x65, 0x73,
+	0x74, 0x5f, 0x64, 0x61, 0x74, 0x61, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x33,
+}
+
+var (
+	file_demo_proto_rawDescOnce sync.Once
+	file_demo_proto_rawDescData = file_demo_proto_rawDesc
+)
+
+func file_demo_proto_rawDescGZIP() []byte {
+	file_demo_proto_rawDescOnce.Do(func() {
+		file_demo_proto_rawDescData = protoimpl.X.CompressGZIP(file_demo_proto_rawDescData)
+	})
+	return file_demo_proto_rawDescData
+}
+
+var file_demo_proto_msgTypes = make([]protoimpl.MessageInfo, 2)
+var file_demo_proto_goTypes = []interface{}{
+	(*EchoRequest)(nil),            // 0: test_data.EchoRequest
+	(*EchoRequest_SubMessage)(nil), // 1: test_data.EchoRequest.SubMessage
+}
+var file_demo_proto_depIdxs = []int32{
+	1, // 0: test_data.EchoRequest.subs:type_name -> test_data.EchoRequest.SubMessage
+	1, // [1:1] is the sub-list for method output_type
+	1, // [1:1] is the sub-list for method input_type
+	1, // [1:1] is the sub-list for extension type_name
+	1, // [1:1] is the sub-list for extension extendee
+	0, // [0:1] is the sub-list for field type_name
+}
+
+func init() { file_demo_proto_init() }
+func file_demo_proto_init() {
+	if File_demo_proto != nil {
+		return
+	}
+	file_api_proto_init()
+	if !protoimpl.UnsafeEnabled {
+		file_demo_proto_msgTypes[0].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*EchoRequest); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+		file_demo_proto_msgTypes[1].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*EchoRequest_SubMessage); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+	}
+	type x struct{}
+	out := protoimpl.TypeBuilder{
+		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
+			RawDescriptor: file_demo_proto_rawDesc,
+			NumEnums:      0,
+			NumMessages:   2,
+			NumExtensions: 0,
+			NumServices:   0,
+		},
+		GoTypes:           file_demo_proto_goTypes,
+		DependencyIndexes: file_demo_proto_depIdxs,
+		MessageInfos:      file_demo_proto_msgTypes,
+	}.Build()
+	File_demo_proto = out.File
+	file_demo_proto_rawDesc = nil
+	file_demo_proto_goTypes = nil
+	file_demo_proto_depIdxs = nil
+}
diff --git a/validator/validator.go b/validator/validator.go
index 577bffc..faaab8e 100644
--- a/validator/validator.go
+++ b/validator/validator.go
@@ -48,6 +48,24 @@ func New(tagName string) *Validator {
 	return v
 }
 
+var (
+	WithTagName = tagexpr.WithTagName
+	WithCheckPublicOnly  = tagexpr.WithCheckPublicOnly
+)
+
+func NewValidator(opts ...tagexpr.TagExprOption) *Validator {
+	vm := tagexpr.New("")
+	for _, opt := range opts {
+		opt(vm)
+	}
+
+	v := &Validator{
+		vm:         vm,
+		errFactory: defaultErrorFactory,
+	}
+	return v
+}
+
 // VM returns the struct tag expression interpreter.
 func (v *Validator) VM() *tagexpr.VM {
 	return v.vm
diff --git a/validator/validator_pb_test.go b/validator/validator_pb_test.go
new file mode 100644
index 0000000..bc251da
--- /dev/null
+++ b/validator/validator_pb_test.go
@@ -0,0 +1,91 @@
+package validator_test
+
+import (
+	"encoding/json"
+	"testing"
+
+	"github.com/bytedance/go-tagexpr/v2/test_data"
+	vd "github.com/bytedance/go-tagexpr/v2/validator"
+	"github.com/stretchr/testify/assert"
+	"google.golang.org/protobuf/encoding/protojson"
+	"google.golang.org/protobuf/proto"
+)
+
+func TestVdFailWithPbMsg(t *testing.T) {
+	// Protobuf message got from protojson does not work
+	td := &test_data.EchoRequest{}
+	assert.NoError(t, protojson.Unmarshal([]byte(`{"msg": "hello"}`), td))
+	assert.Equal(t, "hello", td.Msg)
+	assert.Error(t, vd.Validate(td), "unsupport data: nil")
+
+	td1 := proto.Clone(td).(*test_data.EchoRequest)
+	assert.Equal(t, "hello", td1.Msg)
+	assert.Error(t, vd.Validate(td1), "unsupport data: nil")
+
+	td2 := &test_data.EchoRequest{}
+	proto.Merge(td2, td)
+	assert.Equal(t, "hello", td2.Msg)
+	assert.Error(t, vd.Validate(td2), "unsupport data: nil")
+}
+
+func TestVdWithPbMsg(t *testing.T) {
+	// Direct assign value works
+	{
+		td := &test_data.EchoRequest{Msg: "hello"}
+		assert.NoError(t, vd.Validate(td))
+	}
+	{
+		td := &test_data.EchoRequest{Msg: "hi"}
+		assert.ErrorContains(t, vd.Validate(td), "invalid parameter: Msg")
+	}
+	// json works
+	{
+		td := &test_data.EchoRequest{}
+		assert.NoError(t, json.Unmarshal([]byte(`{"msg": "hello"}`), td))
+		assert.Equal(t, "hello", td.Msg)
+		assert.NoError(t, vd.Validate(td))
+	}
+	{
+		td := &test_data.EchoRequest{}
+		assert.NoError(t, json.Unmarshal([]byte(`{"msg": "hi"}`), td))
+		assert.Equal(t, "hi", td.Msg)
+		assert.ErrorContains(t, vd.Validate(td), "invalid parameter: Msg")
+	}
+	// protojson works sometime for failure check
+	{
+		td := &test_data.EchoRequest{}
+		assert.NoError(t, protojson.Unmarshal([]byte(`{"msg": "hi"}`), td))
+		assert.Equal(t, "hi", td.Msg)
+		assert.ErrorContains(t, vd.Validate(td), "invalid parameter: Msg")
+	}
+}
+
+func TestVdFixedWithPbMsg(t *testing.T) {
+	validator := vd.NewValidator(vd.WithTagName("vd"), vd.WithCheckPublicOnly())
+	{
+		td := &test_data.EchoRequest{}
+		assert.NoError(t, protojson.Unmarshal([]byte(`{"msg": "hello"}`), td))
+		assert.Equal(t, "hello", td.Msg)
+		assert.NoError(t, validator.Validate(td))
+	}
+	{
+		td := &test_data.EchoRequest{}
+		assert.NoError(t, protojson.Unmarshal([]byte(`{"msg": "hi"}`), td))
+		assert.Equal(t, "hi", td.Msg)
+		assert.ErrorContains(t, validator.Validate(td), "invalid parameter: Msg")
+	}
+	{
+		td := &test_data.EchoRequest{}
+		assert.NoError(t, protojson.Unmarshal([]byte(`{"msg": "hello", "subs": [{"msg": "world"}]}`), td))
+		assert.Equal(t, "hello", td.Msg)
+		assert.Equal(t, "world", td.Subs[0].Msg)
+		assert.NoError(t, validator.Validate(td))
+	}
+	{
+		td := &test_data.EchoRequest{}
+		assert.NoError(t, protojson.Unmarshal([]byte(`{"msg": "hello", "subs": [{"msg": "bob"}]}`), td))
+		assert.Equal(t, "hello", td.Msg)
+		assert.Equal(t, "bob", td.Subs[0].Msg)
+		assert.ErrorContains(t, validator.Validate(td), "invalid parameter: Subs[0].Msg")
+	}
+}