code: public function json()
      {
          /*
           * TODO Remove in Yii 2.1
           *
           * Disabled due to bug in MySQL extension
           * @link https://bugs.php.net/bug.php?id=70384
           */
          if (version_compare(PHP_VERSION, '5.6', '<') && $this->getDb()->getDriverName() === 'mysql') {
              throw new \yii\base\Exception('JSON column type is not supported in PHP < 5.6');
          }
  
          return $this->getDb()->getSchema()->createColumnSchemaBuilder(Schema::TYPE_JSON);
      }
docs: Creates a JSON column.
  @return ColumnSchemaBuilder the column instance which can be further customized.
  @since 2.0.14
  @throws \yii\base\Exception