Question

I have a “answers” table and a “users” table. I need to link them but I have to use custom keys on both tables (i.e. I’m not using ‘id’ in any of them). Both tables have the “facebook_id” field which connects them.

In the Answer model I define a “belongs_to” User, and I can define Answer’s foreign_key, but how can I say “link Answer to User using facebook_id on both tables”?

Answer 1

It appears the only way this is possible is by changing your models _primary_key to facebook_id

Upon investigation of the ORM class structure you’ll see the tables are joined like so

    elseif (isset($this->_belongs_to[$column]))
    {
        $this->_load();

        $model = $this->_related($column);

        // Use this model's column and foreign model's primary key
        $col = $model->_table_name.'.'.$model->_primary_key;
        $val = $this->_object[$this->_belongs_to[$column]['foreign_key']];

        $model->where($col, '=', $val)->find();

        return $model;
    }

As you mentioned you can use

protected $_belongs_to = array('user' => array('foreign_key' => 'facebook_id')

But that would result in

answers.id = users.facebook_id

But if you change the primary key on answers from id to facebook_id like so

protected $_primary_key = 'facebook_id';

Then of course the final query would result in

answers.facebook_id = users.facebook_id