AddIndex for multiple columns

README.md

@@ -923,6 +923,16 @@ for rows.Next() {
 db.Table("users").Select("users.name, emails.email").Joins("left join emails on emails.user_id = users.id").Scan(&results)
 ```
 
+## Indices
+
+```go
+// single column index
+db.Model(User{}).AddIndex("idx_user_name", "name")
+
+// multiple column index
+db.Model(User{}).AddIndex("idx_user_name", "name", "age")
+```
+
 ## Run Raw SQL
 
 ```go
@@ -1032,7 +1042,7 @@ db.Where("email = ?", "x@example.org").Attrs(User{RegisteredIp: "111.111.111.111
   share or not? transaction?
 * Github Pages
 * Includes
-* AlertColumn, DropColumn, AddIndex, RemoveIndex
+* AlertColumn, DropColumn
 
 # Author
 

main.go

@@ -314,8 +314,8 @@ func (s *DB) DropColumn(column string) *DB {
 	return s
 }
 
-func (s *DB) AddIndex(column string, indexName ...string) *DB {
-	s.clone().NewScope(s.Value).addIndex(column, indexName...)
+func (s *DB) AddIndex(indexName string, column ...string) *DB {
+	s.clone().NewScope(s.Value).addIndex(indexName, column...)
 	return s
 }
 

main_test.go

@@ -83,6 +83,16 @@ type User struct {
 	IgnoreStringSlice []string `sql:"-"`
 }
 
+type UserCompany struct {
+	Id        int64
+	UserId    int64
+	CompanyId int64
+}
+
+func (t UserCompany) TableName() string {
+	return "user_companies"
+}
+
 type CreditCard struct {
 	Id        int8
 	Number    string
@@ -179,6 +189,7 @@ func init() {
 	db.Exec("drop table roles")
 	db.Exec("drop table companies")
 	db.Exec("drop table animals")
+	db.Exec("drop table user_companies")
 
 	if err = db.CreateTable(&Animal{}).Error; err != nil {
 		panic(fmt.Sprintf("No error should happen when create table, but got %+v", err))
@@ -212,6 +223,10 @@ func init() {
 		panic(fmt.Sprintf("No error should happen when create table, but got %+v", err))
 	}
 
+	if err = db.AutoMigrate(UserCompany{}).Error; err != nil {
+		panic(fmt.Sprintf("No error should happen when create table, but got %+v", err))
+	}
+
 	var shortForm = "2006-01-02 15:04:05"
 	t1, _ = time.Parse(shortForm, "2000-10-27 12:02:40")
 	t2, _ = time.Parse(shortForm, "2002-01-01 00:00:00")
@@ -2003,3 +2018,15 @@ func TestSelectWithEscapedFieldName(t *testing.T) {
 		t.Errorf("Expected one name, but got: %d", len(names))
 	}
 }
+
+func TestIndices(t *testing.T) {
+	if err := db.Model(&UserCompany{}).AddIndex("idx_user_company_user", "user_id").Error; err != nil {
+		t.Errorf("Got error when tried to create index: %+v", err)
+	}
+	if err := db.Model(&UserCompany{}).RemoveIndex("idx_user_company_user").Error; err != nil {
+		t.Errorf("Got error when tried to remove index: %+v", err)
+	}
+	if err := db.Model(&UserCompany{}).AddIndex("idx_user_company_user_company", "user_id", "company_id").Error; err != nil {
+		t.Errorf("Got error when tried to create index: %+v", err)
+	}
+}

scope_private.go

@@ -431,15 +431,13 @@ func (scope *Scope) dropColumn(column string) {
 	scope.Raw(fmt.Sprintf("ALTER TABLE %v DROP COLUMN %v", scope.Quote(scope.TableName()), scope.Quote(column))).Exec()
 }
 
-func (scope *Scope) addIndex(column string, names ...string) {
-	var indexName string
-	if len(names) > 0 {
-		indexName = names[0]
-	} else {
-		indexName = fmt.Sprintf("index_%v_on_%v", scope.TableName(), column)
+func (scope *Scope) addIndex(indexName string, column ...string) {
+	var columns []string
+	for _, name := range column {
+		columns = append(columns, scope.Quote(name))
 	}
 
-	scope.Raw(fmt.Sprintf("CREATE INDEX %v ON %v(%v);", indexName, scope.Quote(scope.TableName()), scope.Quote(column))).Exec()
+	scope.Raw(fmt.Sprintf("CREATE INDEX %v ON %v(%v);", indexName, scope.Quote(scope.TableName()), strings.Join(columns, ", "))).Exec()
 }
 
 func (scope *Scope) removeIndex(indexName string) {