help with relations()

Yii 1.1 General Discussion
1

I’m trying to wrap my mind around how the relations() method works. For instance, in the Yii Guide (Relational Active Record

), this example is given for a MANY_MANY relationship in the Post model:

‘categories’=>array(self::MANY_MANY, ‘Category’, ‘tbl_post_category(post_id, category_id)’),

How is Yii creating this relationship? Is the method getting category_id’s from the Category model where the category_id exists in the tbl_post_category only after filtering on post_id? I’m pretty sure it’s doing this, but I don’t understand how. In the Post table referenced in the guide, the ID field is named “ID”, not post_id. All I can guess is that Yii is looking at the underlying SQL relationships to do the actual linking. Then again, the Guide states:

"it is recommended that primary-foreign key constraints are declared for tables that need to be joined"

Not required.

2

Anyone?

3

First, Scan all table in the databases when used gii build model.

Gii base on table foreign key then find relation. e.g.

The table tbl_post_category used innodb engine and assign foreign key post_id to table post.post_id and table category.category.category_id.

Last, When used gii build model for tabe post’s model. Gii auto automatic scan tbl_post_category and find relation and create


'categories'=>array(self::MANY_MANY, 'Category', 'tbl_post_category(post_id, category_id)')

, code on relations method in the Post model.