From dbb28729cc7e35e802b6b3df5084799518b8f72b Mon Sep 17 00:00:00 2001
From: nlimpid <jshuangzl@gmail.com>
Date: Mon, 20 Mar 2023 13:21:08 +0800
Subject: [PATCH] feat: support empty tag (#136)

Co-authored-by: jieshuang <shuang.jie@longbridge.sg>
---
 scanner/scanner.go      | 25 +++++++++++++------------
 scanner/scanner_test.go | 37 ++++++++++++++++++++++++++++++-------
 2 files changed, 43 insertions(+), 19 deletions(-)

diff --git a/scanner/scanner.go b/scanner/scanner.go
index c270617..192b8d1 100644
--- a/scanner/scanner.go
+++ b/scanner/scanner.go
@@ -23,7 +23,7 @@ type ByteUnmarshaler interface {
 	UnmarshalByte(data []byte) error
 }
 
-//Rows defines methods that scanner needs, which database/sql.Rows already implements
+// Rows defines methods that scanner needs, which database/sql.Rows already implements
 type Rows interface {
 	Close() error
 
@@ -41,7 +41,7 @@ const (
 )
 
 var (
-	userDefinedTagName string
+	userDefinedTagName *string
 	//ErrTargetNotSettable means the second param of Bind is not settable
 	ErrTargetNotSettable = errors.New("[scanner]: target is not settable! a pointer is required")
 	//ErrNilRows means the first param can't be a nil
@@ -52,15 +52,15 @@ var (
 	ErrEmptyResult = errors.New(`[scanner]: empty result`)
 )
 
-//SetTagName can be set only once
+// SetTagName can be set only once
 func SetTagName(name string) {
-	if userDefinedTagName != "" {
+	if userDefinedTagName != nil {
 		return
 	}
-	userDefinedTagName = name
+	userDefinedTagName = &name
 }
 
-//ScanErr will be returned if an underlying type couldn't be AssignableTo type of target field
+// ScanErr will be returned if an underlying type couldn't be AssignableTo type of target field
 type ScanErr struct {
 	structName, fieldName string
 	from, to              reflect.Type
@@ -202,7 +202,7 @@ func ScanClose(rows Rows, target interface{}) error {
 	return err
 }
 
-//caller must guarantee to pass a &slice as the second param
+// caller must guarantee to pass a &slice as the second param
 func bindSlice(arr []map[string]interface{}, target interface{}) error {
 	targetObj := reflect.ValueOf(target)
 	if !targetObj.Elem().CanSet() {
@@ -333,11 +333,12 @@ func resolveDataFromRows(rows Rows) ([]map[string]interface{}, error) {
 }
 
 func lookUpTagName(typeObj reflect.StructField) (string, bool) {
-	var tName string
-	if "" != userDefinedTagName {
-		tName = userDefinedTagName
-	} else {
-		tName = DefaultTagName
+	tName := DefaultTagName
+	if userDefinedTagName != nil {
+		tName = *userDefinedTagName
+	}
+	if tName == "" {
+		return typeObj.Name, true
 	}
 	name, ok := typeObj.Tag.Lookup(tName)
 	if !ok {
diff --git a/scanner/scanner_test.go b/scanner/scanner_test.go
index 0ced576..8846b6c 100644
--- a/scanner/scanner_test.go
+++ b/scanner/scanner_test.go
@@ -948,15 +948,37 @@ func Test_sql_scanner_with_pointer(t *testing.T) {
 	}
 }
 
+func TestBindWithEmptyTag(t *testing.T) {
+	emptyStr := ""
+	userDefinedTagName = &emptyStr
+	type Person struct {
+		Name string
+		Age  int
+	}
+	var p Person
+	name := "deen"
+	age := 23
+	var mp = map[string]interface{}{
+		"Name": name,
+		"Age":  age,
+	}
+	err := bind(mp, &p)
+	should := require.New(t)
+	should.NoError(err)
+	should.Equal(name, p.Name)
+	should.Equal(age, p.Age)
+}
+
 func TestTagSetOnlyOnce(t *testing.T) {
-	userDefinedTagName = "a"
+	a := "a"
+	userDefinedTagName = &a
 	SetTagName("foo")
-	require.Equal(t, "a", userDefinedTagName)
-	userDefinedTagName = ""
+	require.Equal(t, "a", *userDefinedTagName)
+	userDefinedTagName = nil
 	SetTagName("foo")
-	require.Equal(t, "foo", userDefinedTagName)
+	require.Equal(t, "foo", *userDefinedTagName)
 	// restore default tag
-	userDefinedTagName = DefaultTagName
+	userDefinedTagName = nil
 }
 
 type fakeRows struct {
@@ -1044,7 +1066,8 @@ func TestScanMock(t *testing.T) {
 		Age  int    `ddb:"age"`
 	}
 	var boys []curdBoy
-	userDefinedTagName = "ddb"
+	defaultTag := DefaultTagName
+	userDefinedTagName = &defaultTag
 	err := Scan(scannn, &boys)
 	should.NoError(err)
 	should.Equal("deen", boys[0].Name)
@@ -1061,7 +1084,7 @@ func TestScanEmpty(t *testing.T) {
 		Age  int    `ddb:"age"`
 	}
 	var boys []curdBoy
-	userDefinedTagName = "ddb"
+	*userDefinedTagName = "ddb"
 	err := Scan(scannn, &boys)
 	should.NoError(err)
 	should.Equal(0, len(boys))