Re: Correct model associations

Assuming you are using CakePHP 2.x

It is a good idea to define a primary key in your HABTM table - in the books_users table (name should be alphabetic order, but you can deviate). Thus your table definition is:
books_users
id, book_id, user_id

What is your comment table reflecting?
1) comments added to a book by a user?
2) comments added to a book_user?

To me it sounds like you have implemented 2) - if that is so, please clarify your reason :)

I would go with 1) - so that your comments table definition becomes:
comments
id, book_id, user_id, comment, ...
where book_id is a reference to the books table and user_id is a reference to the users table.

Enjoy, John


On Friday, 6 February 2015 22:46:08 UTC+2, gt0p wrote:

I am trying to bind 3 tables and I am having problems with proper relations. 

Table users (pk id), books (pk id), users_books (user_id, book_id), comments (pk and foreign key book_id, user_id -> with reference to users_books)

Here are the models:

Book

  public $hasAndBelongsToMany = array(

      'User' =>

      array(

        'className' => 'User',

          'joinTable' => 'users_books',

            'foreignKey' => 'book_id',

            'associationForeignKey' => 'user_id',

            'unique' => true,

        'conditions' => '',

        'fields' => '',

        'order' => '',

        'limit' => '',

        'offset' => '',

        'finderQuery' => '',

      //  'with' => 'UserBook'

    ),);

    public $hasMany = array('Comment'=>array('className'=>'Comment'));

Comment:

  public $belongsTo = array (

    'Book' => array (

'className'=>'Book',

    )

  );

When I try to save with the saveAll method I got: 

Error: SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (`metabook`.`comments`, CONSTRAINT `comments_ibfk_1` FOREIGN KEY (`user_id`, `book_id`) REFERENCES `users_books` (`user_id`, `book_id`))  

I know that this is not according to the cakephp conventions, but what I can do to bind those tables?

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