feat: add MapColumns method (#6901)

* add MapColumns method

* fix MapColumns desc

* add TestMapColumns

chainable_api.go

@@ -185,6 +185,13 @@ func (db *DB) Omit(columns ...string) (tx *DB) {
 	return
 }
 
+// MapColumns modify the column names in the query results to facilitate align to the corresponding structural fields
+func (db *DB) MapColumns(m map[string]string) (tx *DB) {
+	tx = db.getInstance()
+	tx.Statement.ColumnMapping = m
+	return
+}
+
 // Where add conditions
 //
 // See the [docs] for details on the various formats that where clauses can take. By default, where clauses chain with AND.

scan.go

@@ -131,6 +131,15 @@ func Scan(rows Rows, db *DB, mode ScanMode) {
 		onConflictDonothing = mode&ScanOnConflictDoNothing != 0
 	)
 
+	if len(db.Statement.ColumnMapping) > 0 {
+		for i, column := range columns {
+			v, ok := db.Statement.ColumnMapping[column]
+			if ok {
+				columns[i] = v
+			}
+		}
+	}
+
 	db.RowsAffected = 0
 
 	switch dest := db.Statement.Dest.(type) {

statement.go

@@ -32,6 +32,7 @@ type Statement struct {
 	Distinct             bool
 	Selects              []string          // selected columns
 	Omits                []string          // omit columns
+	ColumnMapping        map[string]string // map columns
 	Joins                []join
 	Preloads             map[string][]interface{}
 	Settings             sync.Map
@@ -513,6 +514,7 @@ func (stmt *Statement) clone() *Statement {
 		Distinct:             stmt.Distinct,
 		Selects:              stmt.Selects,
 		Omits:                stmt.Omits,
+		ColumnMapping:        stmt.ColumnMapping,
 		Preloads:             map[string][]interface{}{},
 		ConnPool:             stmt.ConnPool,
 		Schema:               stmt.Schema,

tests/query_test.go

@@ -860,6 +860,28 @@ func TestOmitWithAllFields(t *testing.T) {
 	}
 }
 
+func TestMapColumns(t *testing.T) {
+	user := User{Name: "MapColumnsUser", Age: 12}
+	DB.Save(&user)
+
+	type result struct {
+		Name     string
+		Nickname string
+		Age      uint
+	}
+	var res result
+	DB.Table("users").Where("name = ?", user.Name).MapColumns(map[string]string{"name": "nickname"}).Scan(&res)
+	if res.Nickname != user.Name {
+		t.Errorf("Expected res.Nickname to be %s, but got %s", user.Name, res.Nickname)
+	}
+	if res.Name != "" {
+		t.Errorf("Expected res.Name to be empty, but got %s", res.Name)
+	}
+	if res.Age != user.Age {
+		t.Errorf("Expected res.Age to be %d, but got %d", user.Age, res.Age)
+	}
+}
+
 func TestPluckWithSelect(t *testing.T) {
 	users := []User{
 		{Name: "pluck_with_select_1", Age: 25},
@@ -1194,7 +1216,6 @@ func TestSubQueryWithRaw(t *testing.T) {
 			Where("age >= ? and name in (?)", 20, []string{"subquery_raw_1", "subquery_raw_3"}).
 			Group("name"),
 	).Count(&count).Error
-
 	if err != nil {
 		t.Errorf("Expected to get no errors, but got %v", err)
 	}
@@ -1210,7 +1231,6 @@ func TestSubQueryWithRaw(t *testing.T) {
 			Not("age <= ?", 10).Not("name IN (?)", []string{"subquery_raw_1", "subquery_raw_3"}).
 			Group("name"),
 	).Count(&count).Error
-
 	if err != nil {
 		t.Errorf("Expected to get no errors, but got %v", err)
 	}