yii\db\ColumnSchemaBuilder::buildLengthString PHP Method

    protected function buildLengthString()
    {
        if ($this->length === null || $this->length === []) {
            return '';
        }
        if (is_array($this->length)) {
            $this->length = implode(',', $this->length);
        }
        return "({$this->length})";
    }