Add HasIndex method for dialect interface

README.md

@@ -60,7 +60,7 @@ type Address struct {
 	ID       int
 	Address1 string         `sql:"not null;unique"` // Set field as not nullable and unique
 	Address2 string         `sql:"type:varchar(100);unique"`
-	Post     sql.NullString `sql:not null`
+	Post     sql.NullString `sql:"not null"`
 }
 
 type Language struct {

common_dialect.go

@@ -86,13 +86,19 @@ func (s *commonDialect) databaseName(scope *Scope) string {
 
 func (s *commonDialect) HasTable(scope *Scope, tableName string) bool {
 	var count int
-	scope.NewDB().Raw("SELECT count(*) FROM INFORMATION_SCHEMA.tables WHERE table_name = ? AND table_schema = ?", tableName, s.databaseName(scope)).Row().Scan(&count)
+	scope.NewDB().Raw("SELECT count(*) FROM INFORMATION_SCHEMA.TABLES WHERE table_name = ? AND table_schema = ?", tableName, s.databaseName(scope)).Row().Scan(&count)
 	return count > 0
 }
 
 func (s *commonDialect) HasColumn(scope *Scope, tableName string, columnName string) bool {
 	var count int
-	scope.NewDB().Raw("SELECT count(*) FROM information_schema.columns WHERE table_schema = ? AND table_name = ? AND column_name = ?", s.databaseName(scope), tableName, columnName).Row().Scan(&count)
+	scope.NewDB().Raw("SELECT count(*) FROM INFORMATION_SCHEMA.COLUMNS WHERE table_schema = ? AND table_name = ? AND column_name = ?", s.databaseName(scope), tableName, columnName).Row().Scan(&count)
+	return count > 0
+}
+
+func (s *commonDialect) HasIndex(scope *Scope, tableName string, indexName string) bool {
+	var count int
+	scope.NewDB().Raw("SELECT count(*) FROM INFORMATION_SCHEMA.STATISTICS where table_name = ? AND index_name = ?", tableName, indexName).Row().Scan(&count)
 	return count > 0
 }
 

customize_column_test.go

@@ -23,7 +23,7 @@ func TestCustomizeColumn(t *testing.T) {
 	DB.DropTable(&CustomizeColumn{})
 	DB.AutoMigrate(&CustomizeColumn{})
 
-	scope := DB.Model("").NewScope(&CustomizeColumn{})
+	scope := DB.NewScope(&CustomizeColumn{})
 	if !scope.Dialect().HasColumn(scope, scope.TableName(), col) {
 		t.Errorf("CustomizeColumn should have column %s", col)
 	}

dialect.go

@@ -16,6 +16,7 @@ type Dialect interface {
 	Quote(key string) string
 	HasTable(scope *Scope, tableName string) bool
 	HasColumn(scope *Scope, tableName string, columnName string) bool
+	HasIndex(scope *Scope, tableName string, indexName string) bool
 	RemoveIndex(scope *Scope, indexName string)
 }
 

main.go

@@ -399,6 +399,16 @@ func (s *DB) AddIndex(indexName string, column ...string) *DB {
 	return s
 }
 
+func (s *DB) AddUniqueIndex(indexName string, column ...string) *DB {
+	s.clone().NewScope(s.Value).addIndex(true, indexName, column...)
+	return s
+}
+
+func (s *DB) RemoveIndex(indexName string) *DB {
+	s.clone().NewScope(s.Value).removeIndex(indexName)
+	return s
+}
+
 /*
 Add foreign key to the given scope
 
@@ -410,16 +420,6 @@ func (s *DB) AddForeignKey(field string, dest string, onDelete string, onUpdate
 	return s
 }
 
-func (s *DB) AddUniqueIndex(indexName string, column ...string) *DB {
-	s.clone().NewScope(s.Value).addIndex(true, indexName, column...)
-	return s
-}
-
-func (s *DB) RemoveIndex(indexName string) *DB {
-	s.clone().NewScope(s.Value).removeIndex(indexName)
-	return s
-}
-
 func (s *DB) Association(column string) *Association {
 	var err error
 	scope := s.clone().NewScope(s.Value)

migration_test.go

@@ -30,22 +30,43 @@ func TestIndexes(t *testing.T) {
 		t.Errorf("Got error when tried to create index: %+v", err)
 	}
 
+	scope := DB.NewScope(&Email{})
+	if !scope.Dialect().HasIndex(scope, scope.TableName(), "idx_email_email") {
+		t.Errorf("Email should have index idx_email_email")
+	}
+
 	if err := DB.Model(&Email{}).RemoveIndex("idx_email_email").Error; err != nil {
 		t.Errorf("Got error when tried to remove index: %+v", err)
 	}
 
+	if scope.Dialect().HasIndex(scope, scope.TableName(), "idx_email_email") {
+		t.Errorf("Email's index idx_email_email should be deleted")
+	}
+
 	if err := DB.Model(&Email{}).AddIndex("idx_email_email_and_user_id", "user_id", "email").Error; err != nil {
 		t.Errorf("Got error when tried to create index: %+v", err)
 	}
 
+	if !scope.Dialect().HasIndex(scope, scope.TableName(), "idx_email_email_and_user_id") {
+		t.Errorf("Email should have index idx_email_email_and_user_id")
+	}
+
 	if err := DB.Model(&Email{}).RemoveIndex("idx_email_email_and_user_id").Error; err != nil {
 		t.Errorf("Got error when tried to remove index: %+v", err)
 	}
 
+	if scope.Dialect().HasIndex(scope, scope.TableName(), "idx_email_email_and_user_id") {
+		t.Errorf("Email's index idx_email_email_and_user_id should be deleted")
+	}
+
 	if err := DB.Model(&Email{}).AddUniqueIndex("idx_email_email_and_user_id", "user_id", "email").Error; err != nil {
 		t.Errorf("Got error when tried to create index: %+v", err)
 	}
 
+	if !scope.Dialect().HasIndex(scope, scope.TableName(), "idx_email_email_and_user_id") {
+		t.Errorf("Email should have index idx_email_email_and_user_id")
+	}
+
 	if DB.Save(&User{Name: "unique_indexes", Emails: []Email{{Email: "user1@example.comiii"}, {Email: "user1@example.com"}, {Email: "user1@example.com"}}}).Error == nil {
 		t.Errorf("Should get to create duplicate record when having unique index")
 	}
@@ -54,6 +75,10 @@ func TestIndexes(t *testing.T) {
 		t.Errorf("Got error when tried to remove index: %+v", err)
 	}
 
+	if scope.Dialect().HasIndex(scope, scope.TableName(), "idx_email_email_and_user_id") {
+		t.Errorf("Email's index idx_email_email_and_user_id should be deleted")
+	}
+
 	if DB.Save(&User{Name: "unique_indexes", Emails: []Email{{Email: "user1@example.com"}, {Email: "user1@example.com"}}}).Error != nil {
 		t.Errorf("Should be able to create duplicated emails after remove unique index")
 	}

mssql.go

@@ -98,6 +98,12 @@ func (s *mssql) HasColumn(scope *Scope, tableName string, columnName string) boo
 	return count > 0
 }
 
+func (s *mssql) HasIndex(scope *Scope, tableName string, indexName string) bool {
+	var count int
+	scope.NewDB().Raw("SELECT count(*) FROM sys.indexes WHERE name=? AND object_id=OBJECT_ID(?)", indexName, tableName).Row().Scan(&count)
+	return count > 0
+}
+
 func (s *mssql) RemoveIndex(scope *Scope, indexName string) {
 	scope.NewDB().Exec(fmt.Sprintf("DROP INDEX %v ON %v", indexName, scope.QuotedTableName()))
 }

mysql.go

@@ -96,6 +96,12 @@ func (s *mysql) HasColumn(scope *Scope, tableName string, columnName string) boo
 	return count > 0
 }
 
+func (s *mysql) HasIndex(scope *Scope, tableName string, indexName string) bool {
+	var count int
+	scope.NewDB().Raw("SELECT count(*) FROM INFORMATION_SCHEMA.STATISTICS where table_name = ? AND index_name = ?", tableName, indexName).Row().Scan(&count)
+	return count > 0
+}
+
 func (s *mysql) RemoveIndex(scope *Scope, indexName string) {
 	scope.NewDB().Exec(fmt.Sprintf("DROP INDEX %v ON %v", indexName, scope.QuotedTableName()))
 }

postgres.go

@@ -87,7 +87,7 @@ func (s *postgres) HasTable(scope *Scope, tableName string) bool {
 
 func (s *postgres) HasColumn(scope *Scope, tableName string, columnName string) bool {
 	var count int
-	scope.NewDB().Raw("SELECT count(*) FROM information_schema.columns WHERE table_name = ? AND column_name = ?", tableName, columnName).Row().Scan(&count)
+	scope.NewDB().Raw("SELECT count(*) FROM INFORMATION_SCHEMA.columns WHERE table_name = ? AND column_name = ?", tableName, columnName).Row().Scan(&count)
 	return count > 0
 }
 
@@ -95,6 +95,12 @@ func (s *postgres) RemoveIndex(scope *Scope, indexName string) {
 	scope.NewDB().Exec(fmt.Sprintf("DROP INDEX %v", indexName))
 }
 
+func (s *postgres) HasIndex(scope *Scope, tableName string, indexName string) bool {
+	var count int
+	scope.NewDB().Raw("SELECT count(*) FROM pg_indexes WHERE tablename = ? AND indexname = ?", tableName, indexName).Row().Scan(&count)
+	return count > 0
+}
+
 var hstoreType = reflect.TypeOf(Hstore{})
 
 type Hstore map[string]*string

sqlite3.go

@@ -80,6 +80,12 @@ func (s *sqlite3) HasColumn(scope *Scope, tableName string, columnName string) b
 	return count > 0
 }
 
+func (s *sqlite3) HasIndex(scope *Scope, tableName string, indexName string) bool {
+	var count int
+	scope.NewDB().Raw(fmt.Sprintf("SELECT count(*) FROM sqlite_master WHERE tbl_name = ? AND sql LIKE '%%INDEX %v ON%%'", indexName), tableName).Row().Scan(&count)
+	return count > 0
+}
+
 func (s *sqlite3) RemoveIndex(scope *Scope, indexName string) {
 	scope.NewDB().Exec(fmt.Sprintf("DROP INDEX %v", indexName))
 }