問題描述
Có cách nào để kiểm tra tính toàn vẹn của tham chiếu cho các bảng MyIsam bằng cách sử dụng quan hệ gốc YII không? (Is there a way to check referential integrity for MyIsam tables using YII native relations?)
While I used InnoDB tables I caught FK constraint exceptions from InnoDB engine.
I know that Yii can fetch related tables according to relations(). Besides I need to check referential integrity during other CRUD operations ‑ such as insert, update and delete.
Is there some Yii native mechanism to perform this? Or I should write additional code for this checking?
參考解法
方法 1:
In order to avoid errors from the database you need to write additional code to handle this. I manage it using the beforeDelete() method of my models. Write an if condition to check for referential integrity violations uising the model's relations. You can then either delete the offending records or abort the deletion by not returning 'parent::beforeDelete().'
In this many to many example from a User model we can wrap the 'return parent::beforeDelete()' call in an if to check the relations() of the model in the following way:
protected function beforeDelete() {
if (empty($this‑>tasks))
return parent::beforeDelete();
}
The deletion is aborted if the User is found to have any assigned tasks.
For reference the relation in the model would look like this and requires a third table:
'tasks' => array(self::MANY_MANY, 'Task', 'task_assignment(user_id,task_id)'),
This example is very basic and obviously you may want to implement a more complex way of handling these scenarios which could include deletion of related records or even the updating of them to remove their foreign key references. You will have to decide what works best and makes sense for each of your models and their relations.
(by Peter Lyashevich、ShaunUK)