Calling WithConnection from WithInstance to de-duplicate code

database/mysql/mysql.go

@@ -55,7 +55,7 @@ type Mysql struct {
 }
 
 // connection instance must have `multiStatements` set to true
-func WithConnection(conn *sql.Conn, config *Config) (database.Driver, error) {
+func WithConnection(conn *sql.Conn, config *Config) (*Mysql, error) {
 	if config == nil {
 		return nil, ErrNilConfig
 	}
@@ -66,8 +66,22 @@ func WithConnection(conn *sql.Conn, config *Config) (database.Driver, error) {
 		config: config,
 	}
 
-	if err := mx.setupDefaultConfig(); err != nil {
-		return nil, err
+	if config.DatabaseName == "" {
+		query := `SELECT DATABASE()`
+		var databaseName sql.NullString
+		if err := conn.QueryRowContext(context.Background(), query).Scan(&databaseName); err != nil {
+			return nil, &database.Error{OrigErr: err, Query: []byte(query)}
+		}
+
+		if len(databaseName.String) == 0 {
+			return nil, ErrNoDatabaseName
+		}
+
+		config.DatabaseName = databaseName.String
+	}
+
+	if len(config.MigrationsTable) == 0 {
+		config.MigrationsTable = DefaultMigrationsTable
 	}
 
 	if err := mx.ensureVersionTable(); err != nil {
@@ -79,10 +93,6 @@ func WithConnection(conn *sql.Conn, config *Config) (database.Driver, error) {
 
 // instance must have `multiStatements` set to true
 func WithInstance(instance *sql.DB, config *Config) (database.Driver, error) {
-	if config == nil {
-		return nil, ErrNilConfig
-	}
-
 	if err := instance.Ping(); err != nil {
 		return nil, err
 	}
@@ -92,45 +102,16 @@ func WithInstance(instance *sql.DB, config *Config) (database.Driver, error) {
 		return nil, err
 	}
 
-	mx := &Mysql{
-		conn:   conn,
-		db:     instance,
-		config: config,
-	}
-
-	if err := mx.setupDefaultConfig(); err != nil {
+	mx, err := WithConnection(conn, config)
+	if err != nil {
 		return nil, err
 	}
 
-	if err := mx.ensureVersionTable(); err != nil {
-		return nil, err
-	}
+	mx.db = instance
 
 	return mx, nil
 }
 
-func (m *Mysql) setupDefaultConfig() error {
-	if m.config.DatabaseName == "" {
-		query := `SELECT DATABASE()`
-		var databaseName sql.NullString
-		if err := m.conn.QueryRowContext(context.Background(), query).Scan(&databaseName); err != nil {
-			return &database.Error{OrigErr: err, Query: []byte(query)}
-		}
-
-		if len(databaseName.String) == 0 {
-			return ErrNoDatabaseName
-		}
-
-		m.config.DatabaseName = databaseName.String
-	}
-
-	if len(m.config.MigrationsTable) == 0 {
-		m.config.MigrationsTable = DefaultMigrationsTable
-	}
-
-	return nil
-}
-
 // extractCustomQueryParams extracts the custom query params (ones that start with "x-") from
 // mysql.Config.Params (connection parameters) as to not interfere with connecting to MySQL
 func extractCustomQueryParams(c *mysql.Config) (map[string]string, error) {