diff --git a/.gitignore b/.gitignore
index 2bdc15b..735b1a6 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 /.idea/
 /dist/
+/gtag
 
 # Created by https://www.gitignore.io/api/go,intellij,visualstudiocode,vim,macos
 # Edit at https://www.gitignore.io/?templates=go,intellij,visualstudiocode,vim,macos
@@ -120,7 +121,7 @@ fabric.properties
 .LSOverride
 
 # Icon must end with two \r
-Icon
+Icon
 
 # Thumbnails
 ._*
diff --git a/cmd/gtag/main.go b/cmd/gtag/main.go
index e429f45..e76d794 100644
--- a/cmd/gtag/main.go
+++ b/cmd/gtag/main.go
@@ -5,20 +5,33 @@ import (
 	"flag"
 	"fmt"
 	"os"
+	"strings"
 
 	"github.com/gochore/tag/internal/gtag"
 )
 
 var (
-	file = flag.String("file", "", "source file")
-	name = flag.String("name", "", "struct type name")
+	types = flag.String("types", "", "struct types")
 )
 
 func main() {
 	flag.Parse()
-	_, err := gtag.Generate(context.Background(), *file, *name)
+
+	args := flag.Args()
+	if *types == "" || len(args) != 1 {
+		printUsages()
+		return
+	}
+	dir := args[0]
+
+	_, err := gtag.Generate(context.Background(), dir, strings.Split(*types, ","))
 	if err != nil {
 		fmt.Println(err)
 		os.Exit(1)
 	}
 }
+
+func printUsages() {
+	fmt.Println(`gtag -types A,B dir`)
+	flag.PrintDefaults()
+}
diff --git a/go.mod b/go.mod
index 823193d..2394529 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,9 @@
 module github.com/gochore/tag
 
 go 1.14
+
+require (
+	github.com/gochore/uniq v1.0.0
+	github.com/pmezard/go-difflib v1.0.0
+	golang.org/x/tools v0.0.0-20200505023115-26f46d2f7ef8
+)
diff --git a/go.sum b/go.sum
index e69de29..acdb4ac 100644
--- a/go.sum
+++ b/go.sum
@@ -0,0 +1,23 @@
+github.com/gochore/uniq v1.0.0 h1:qBA8Jm9GhSojZ8vsCI2h5FJGonmItjY9NLBPUaciOYk=
+github.com/gochore/uniq v1.0.0/go.mod h1:zxZBO4/6PcgNuYMrlJCUKOEEpxSejbD6R53GUpSHelk=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/yuin/goldmark v1.1.27/go.mod h1:3hX8gzYuyVAZsxl0MRgGTJEmQBFcNTphYh9decYSb74=
+golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
+golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
+golang.org/x/mod v0.2.0/go.mod h1:s0Qsj1ACt9ePp/hMypM3fl4fZqREWJwdYDEqhRiZZUA=
+golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
+golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20200226121028-0de0cce0169b/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
+golang.org/x/sys v0.0.0-20190412213103-97732733099d/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
+golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
+golang.org/x/tools v0.0.0-20200505023115-26f46d2f7ef8 h1:BMFHd4OFnFtWX46Xj4DN6vvT1btiBxyq+s0orYBqcQY=
+golang.org/x/tools v0.0.0-20200505023115-26f46d2f7ef8/go.mod h1:EkVYQZoAsY45+roYkvgYkIh4xh/qjgUK9TdY2XT94GE=
+golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
+golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
diff --git a/internal/gtag/gtag.go b/internal/gtag/gtag.go
index 507c4b6..923bf52 100644
--- a/internal/gtag/gtag.go
+++ b/internal/gtag/gtag.go
@@ -10,6 +10,9 @@ import (
 	"io/ioutil"
 	"os"
 	"strings"
+
+	"github.com/gochore/uniq"
+	"golang.org/x/tools/go/packages"
 )
 
 type GenerateResult struct {
@@ -17,13 +20,51 @@ type GenerateResult struct {
 	Output  string
 }
 
-func Generate(ctx context.Context, file, name string) (*GenerateResult, error) {
-	f, err := loadFile(file)
+func (r *GenerateResult) String() string {
+	return fmt.Sprintf("%s\n%s", r.Output, r.Content)
+}
+
+func Generate(ctx context.Context, dir string, types []string) ([]*GenerateResult, error) {
+	cmd := fmt.Sprintf("gtag -types %s %s", strings.Join(types, ","), dir)
+
+	types = types[:uniq.Strings(types)]
+
+	pkgs, err := packages.Load(&packages.Config{
+		Mode:    packages.NeedFiles,
+		Context: ctx,
+		Dir:     dir,
+		Env:     os.Environ(),
+		Fset:    token.NewFileSet(),
+	})
 	if err != nil {
 		return nil, err
 	}
 
-	fields, err := parseStructField(f, name)
+	var files []string
+	for _, pkg := range pkgs {
+		files = append(files, pkg.GoFiles...)
+	}
+
+	var ret []*GenerateResult
+	for _, file := range files {
+		result, err := generateFile(ctx, cmd, file, types)
+		if err != nil {
+			return nil, err
+		}
+		if result != nil {
+			ret = append(ret, result)
+		}
+	}
+	for _, v := range ret {
+		if err := v.Commit(); err != nil {
+			return nil, err
+		}
+	}
+	return ret, nil
+}
+
+func generateFile(ctx context.Context, cmd, file string, types []string) (*GenerateResult, error) {
+	f, err := loadFile(file)
 	if err != nil {
 		return nil, err
 	}
@@ -33,10 +74,30 @@ func Generate(ctx context.Context, file, name string) (*GenerateResult, error) {
 	}
 	pkg := f.Name.Name
 
+	fieldM := map[string][]string{}
+	for _, typ := range types {
+		fields, ok := parseStructField(f, typ)
+		if ok {
+			fieldM[typ] = fields
+		}
+	}
+
+	if len(fieldM) == 0 {
+		return nil, nil
+	}
+
 	data := templateData{
 		Package: pkg,
-		Type:    name,
-		Fields:  fields,
+		Command: cmd,
+	}
+
+	for _, typ := range types {
+		if fields, ok := fieldM[typ]; ok {
+			data.Types = append(data.Types, templateDataType{
+				Name:   typ,
+				Fields: fields,
+			})
+		}
 	}
 
 	src, err := format.Source(execute(data))
@@ -49,10 +110,6 @@ func Generate(ctx context.Context, file, name string) (*GenerateResult, error) {
 		Output:  strings.TrimSuffix(file, ".go") + "_tag.go",
 	}
 
-	if err := ret.Commit(); err != nil {
-		return nil, err
-	}
-
 	return ret, nil
 }
 
@@ -73,7 +130,7 @@ func loadFile(name string) (*ast.File, error) {
 	return parser.ParseFile(token.NewFileSet(), name, f, 0)
 }
 
-func parseStructField(f *ast.File, name string) ([]string, error) {
+func parseStructField(f *ast.File, name string) ([]string, bool) {
 	var fields []*ast.Field
 	found := false
 
@@ -96,7 +153,7 @@ func parseStructField(f *ast.File, name string) ([]string, error) {
 	})
 
 	if !found {
-		return nil, fmt.Errorf("can not find struct %q", name)
+		return nil, found
 	}
 
 	var ret []string
@@ -106,5 +163,5 @@ func parseStructField(f *ast.File, name string) ([]string, error) {
 		}
 	}
 
-	return ret, nil
+	return ret, found
 }
diff --git a/internal/gtag/gtag_test.go b/internal/gtag/gtag_test.go
index 3442d61..db07e89 100644
--- a/internal/gtag/gtag_test.go
+++ b/internal/gtag/gtag_test.go
@@ -9,32 +9,22 @@ const testDir = "../../test/internal/"
 
 func TestGenerate(t *testing.T) {
 	type args struct {
-		ctx  context.Context
-		file string
-		name string
+		ctx   context.Context
+		dir   string
+		types []string
 	}
 	tests := []struct {
 		name    string
 		args    args
-		want    []byte
+		want    []*GenerateResult
 		wantErr bool
 	}{
 		{
-			name: "regular",
+			name: "reguler",
 			args: args{
-				ctx:  context.Background(),
-				file: testDir + "regular/user.go",
-				name: "User",
-			},
-			want:    nil,
-			wantErr: false,
-		},
-		{
-			name: "empty",
-			args: args{
-				ctx:  context.Background(),
-				file: testDir + "regular/empty.go",
-				name: "Empty",
+				ctx:   context.Background(),
+				dir:   testDir + "regular/",
+				types: []string{"User", "Empty", "UserName", "UserName"},
 			},
 			want:    nil,
 			wantErr: false,
@@ -42,17 +32,16 @@ func TestGenerate(t *testing.T) {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			got, err := Generate(tt.args.ctx, tt.args.file, tt.args.name)
+			got, err := Generate(tt.args.ctx, tt.args.dir, tt.args.types)
 			if (err != nil) != tt.wantErr {
 				t.Errorf("Generate() error = %v, wantErr %v", err, tt.wantErr)
 				return
 			}
 			//if !reflect.DeepEqual(got, tt.want) {
-			//	t.Errorf("Generate() got = %s, want %s", got, tt.want)
+			//	t.Errorf("Generate() got = %v, want %v", got, tt.want)
 			//}
-			t.Logf("%s", got)
-			if err := got.Commit(); err != nil {
-				t.Error(err)
+			for _, result := range got {
+				t.Log(result)
 			}
 		})
 	}
diff --git a/internal/gtag/template.go b/internal/gtag/template.go
index 4cae6ed..8cb15f3 100644
--- a/internal/gtag/template.go
+++ b/internal/gtag/template.go
@@ -7,24 +7,31 @@ import (
 
 type templateData struct {
 	Package string
-	Type    string
-	Fields  []string
+	Command string
+	Types   []templateDataType
+}
+
+type templateDataType struct {
+	Name   string
+	Fields []string
 }
 
 const templateLayout = `
 // Code generated by gtag. DO NOT EDIT.
 // See: https://github.com/wolfogre/gtag
 
-//go:generate gtag
+//go:generate {{.Command}}
 package {{.Package}}
 
 import "reflect"
 
+{{- range .Types}}
+
 var (
-	valueOf{{.Type}} = {{.Type}}{}
-	typeOf{{.Type}}  = reflect.TypeOf(valueOf{{.Type}})
+	valueOf{{.Name}} = {{.Name}}{}
+	typeOf{{.Name}}  = reflect.TypeOf(valueOf{{.Name}})
 
-{{$type := .Type}}
+{{$type := .Name}}
 {{- range .Fields}}
 	_ = valueOf{{$type}}.{{.}}
 	fieldOf{{$type}}{{.}}, _ = typeOf{{$type}}.FieldByName("{{.}}")
@@ -46,6 +53,8 @@ func ({{$type}}) Tags(tag string) {{$type}}Tags {
 	}
 }
 
+{{- end}}
+
 `
 
 func execute(data templateData) []byte {
diff --git a/internal/gtag/template_test.go b/internal/gtag/template_test.go
index 35afcd8..42fd5be 100644
--- a/internal/gtag/template_test.go
+++ b/internal/gtag/template_test.go
@@ -2,6 +2,8 @@ package gtag
 
 import (
 	"testing"
+
+	"github.com/pmezard/go-difflib/difflib"
 )
 
 func Test_execute(t *testing.T) {
@@ -18,43 +20,47 @@ func Test_execute(t *testing.T) {
 			args: args{
 				data: templateData{
 					Package: "test",
-					Type:    "Test",
-					Fields:  []string{"A", "b"},
+					Types: []templateDataType{
+						{
+							Name:   "test",
+							Fields: []string{"A", "b"},
+						},
+					},
 				},
 			},
 			want: `
 // Code generated by gtag. DO NOT EDIT.
 // See: https://github.com/wolfogre/gtag
 
-//go:generate gtag
+//go:generate 
 package test
 
 import "reflect"
 
 var (
-	valueOfTest = Test{}
-	typeOfTest  = reflect.TypeOf(valueOfTest)
+	valueOftest = test{}
+	typeOftest  = reflect.TypeOf(valueOftest)
 
 
-	_ = valueOfTest.A
-	fieldOfTestA, _ = typeOfTest.FieldByName("A")
-	tagOfTestA = fieldOfTestA.Tag
+	_ = valueOftest.A
+	fieldOftestA, _ = typeOftest.FieldByName("A")
+	tagOftestA = fieldOftestA.Tag
 
-	_ = valueOfTest.b
-	fieldOfTestb, _ = typeOfTest.FieldByName("b")
-	tagOfTestb = fieldOfTestb.Tag
+	_ = valueOftest.b
+	fieldOftestb, _ = typeOftest.FieldByName("b")
+	tagOftestb = fieldOftestb.Tag
 
 )
 
-type TestTags struct {
+type testTags struct {
 	A string
 	b string
 }
 
-func (Test) Tags(tag string) TestTags {
-	return TestTags{
-		A: tagOfTestA.Get(tag),
-		b: tagOfTestb.Get(tag),
+func (test) Tags(tag string) testTags {
+	return testTags{
+		A: tagOftestA.Get(tag),
+		b: tagOftestb.Get(tag),
 	}
 }
 
@@ -63,8 +69,16 @@ func (Test) Tags(tag string) TestTags {
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			if got := execute(tt.args.data); string(got) != tt.want {
+			if got := string(execute(tt.args.data)); got != tt.want {
 				t.Errorf("execute() = %v, want %v", got, tt.want)
+				diff := difflib.UnifiedDiff{
+					A:        difflib.SplitLines(got),
+					B:        difflib.SplitLines(tt.want),
+					FromFile: "got",
+					ToFile:   "want",
+				}
+				text, _ := difflib.GetUnifiedDiffString(diff)
+				t.Log(text)
 			}
 		})
 	}
diff --git a/test/internal/regular/empty_tag.go b/test/internal/regular/empty_tag.go
index bdd7c1b..cc47358 100644
--- a/test/internal/regular/empty_tag.go
+++ b/test/internal/regular/empty_tag.go
@@ -1,7 +1,7 @@
 // Code generated by gtag. DO NOT EDIT.
 // See: https://github.com/wolfogre/gtag
 
-//go:generate gtag
+//go:generate gtag -types User,Empty,UserName,UserName ../../test/internal/regular/
 package regular
 
 import "reflect"
diff --git a/test/internal/regular/user.go b/test/internal/regular/user.go
index d254cd3..3af0409 100644
--- a/test/internal/regular/user.go
+++ b/test/internal/regular/user.go
@@ -1,8 +1,13 @@
 package regular
 
 type User struct {
-	Id    int    `json:"id"`
-	Name  string `json:"name"`
-	Email string `json:"email"`
+	Id    int      `json:"id"`
+	Name  UserName `json:"name"`
+	Email string   `json:"email"`
 	age   int
 }
+
+type UserName struct {
+	First string `json:"first"`
+	Last  string `json:"last"`
+}
diff --git a/test/internal/regular/user_tag.go b/test/internal/regular/user_tag.go
index e58505a..f5f7172 100644
--- a/test/internal/regular/user_tag.go
+++ b/test/internal/regular/user_tag.go
@@ -1,7 +1,7 @@
 // Code generated by gtag. DO NOT EDIT.
 // See: https://github.com/wolfogre/gtag
 
-//go:generate gtag
+//go:generate gtag -types User,Empty,UserName,UserName ../../test/internal/regular/
 package regular
 
 import "reflect"
@@ -42,3 +42,28 @@ func (User) Tags(tag string) UserTags {
 		age:   tagOfUserage.Get(tag),
 	}
 }
+
+var (
+	valueOfUserName = UserName{}
+	typeOfUserName  = reflect.TypeOf(valueOfUserName)
+
+	_                       = valueOfUserName.First
+	fieldOfUserNameFirst, _ = typeOfUserName.FieldByName("First")
+	tagOfUserNameFirst      = fieldOfUserNameFirst.Tag
+
+	_                      = valueOfUserName.Last
+	fieldOfUserNameLast, _ = typeOfUserName.FieldByName("Last")
+	tagOfUserNameLast      = fieldOfUserNameLast.Tag
+)
+
+type UserNameTags struct {
+	First string
+	Last  string
+}
+
+func (UserName) Tags(tag string) UserNameTags {
+	return UserNameTags{
+		First: tagOfUserNameFirst.Get(tag),
+		Last:  tagOfUserNameLast.Get(tag),
+	}
+}
diff --git a/test/internal/regular/user_tag_test.go b/test/internal/regular/user_tag_test.go
index 8495b78..37dc436 100644
--- a/test/internal/regular/user_tag_test.go
+++ b/test/internal/regular/user_tag_test.go
@@ -8,7 +8,7 @@ import (
 func TestUser_Tags(t *testing.T) {
 	type fields struct {
 		Id    int
-		Name  string
+		Name  UserName
 		Email string
 		age   int
 	}
@@ -24,8 +24,11 @@ func TestUser_Tags(t *testing.T) {
 		{
 			name: "regular",
 			fields: fields{
-				Id:    0,
-				Name:  "",
+				Id: 0,
+				Name: UserName{
+					First: "",
+					Last:  "",
+				},
 				Email: "",
 				age:   0,
 			},
@@ -54,3 +57,45 @@ func TestUser_Tags(t *testing.T) {
 		})
 	}
 }
+
+func TestUserName_Tags(t *testing.T) {
+	type fields struct {
+		First string
+		Last  string
+	}
+	type args struct {
+		tag string
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		args   args
+		want   UserNameTags
+	}{
+		{
+			name: "regular",
+			fields: fields{
+				First: "",
+				Last:  "",
+			},
+			args: args{
+				tag: "json",
+			},
+			want: UserNameTags{
+				First: "first",
+				Last:  "last",
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			us := UserName{
+				First: tt.fields.First,
+				Last:  tt.fields.Last,
+			}
+			if got := us.Tags(tt.args.tag); !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("Tags() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}