Matthew Beaumont Thu Jul 07 14:46:24 -0400 2011

Subject: Problem with eager loading and many-to-many

Hi All,

I'm probably doing something wrong here, but I'm having trouble using many-to-many relationships with eager-loading. Here's my table structure:

 1 tbl  `concern` (
 2   `id` int(11) NOT NULL auto_increment,
 3    ...
 4   PRIMARY KEY  (`id`)
 5 )  ;
 6 
 7 tbl  `product` (
 8   `id` int(11) NOT NULL auto_increment,
 9    ...
10   PRIMARY KEY  (`id`)
11 )  ;
12 
13 tbl  `concern_product` (
14   `concern_id` int(11) NOT NULL,
15   `product_id` int(11) NOT NULL,
16 
17 )  ;

then I have the following (partial) model code:

 1 class Concern extends ActiveRecord\Model {
 2 
 3     static $table = 'concern';
 4     static $has_many = array(
 5         array('concern_product'),
 6         array('products', 
 7                    'through' => 'concern_product', 
 8        )
 9  );
10 
11 class ConcernProduct extends ActiveRecord\Model {
12 
13     static $table = 'concern_product';
14 
15     static $belongs_to = array(
16         array('product'),
17         array('concern'),
18     );
19 }

I'm trying to access $concern->products, but it return an empty array. It generates the correct SQL 
1 'SELECT  `product`.* FROM `product` INNER JOIN `concern_product` ON(`product`.id = `concern_product`.product_id) WHERE status != ? AND `concern_id` IN(?)'

and seems to pull the correct records, but then they are filtered out by this part of Relationships.php around line 191:

 1 foreach ($related_models as $related)
 2             {
 3                 if ($related->$query_key == $key_to_match)
 4                 {
 5                     $hash = spl_object_hash($related);
 6 
 7                     if (in_array($hash, $used_models))
 8                         $model->set_relationship_from_eager_load(clone($related), $this->attribute_name);
 9                     else
10                         $model->set_relationship_from_eager_load($related, $this->attribute_name);
11 
12                     $used_models[] = $hash;
13                     $matches++;
14                 }
15             }

Maybe I'm crazy, but doesn't this code look for a direct relationship between the model and related model? Obviously there isn't one in my case since I have a many-to-many relationship through a third table, but it seems to be looking for a key in my product model that relates to my concern model, which doesn't exist.

I'm using the nightly build. Any ideas on what I'm doing wrong?


K. LR Mon Jul 11 14:34:40 -0400 2011

Try something like this :

class Concern extends ActiveRecord\Model {
        static $table = 'concern';
        static $has_many = array( 
            array('products',  'through' => 'concern_product' )
        );
    }
class Product extends ActiveRecord\Model
{    
        static $table = 'product';
        static $has_many = array(
            array('concern_product')
        );
    }
class ConcernProduct extends ActiveRecord\Model
{    
        static $table = 'concern_product';
        static $belongs_to = array(
            array('concern'),
            array('product')
        );
    }

(1-1/1)