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Cakephp model associastion

I have thee following simple model:

  • Item belongsTo CatalogItem
  • CatalogItem hasMany Item, and b开发者_如何学CelongsTo Section
  • Section hasMany CatalogItem
  • I'm trying to get counts of items, grouped by catalogitem, for a certain section- the equivalent of:

    SELECT catalogitem.id, count(*) FROM section LEFT JOIN catalogitem ON section.id=catalogitem.section_id LEFT JOIN item ON item.catalogitem_id=catalogitem.id WHERE section.id=5 GROUP BY catalogitem.id

    So simple in sql, yet I can't get it to work with cake models. Can anyone point as to how to do it with cake models, using the model->find? I can't get it to group by correctly or join correctly on 3 tables :(

    Edit: highly prefer to get the info in single query


    Here's a longer way, "cakeish" way:

    class Item extends AppModel
    {
        /* snip */
        var $virtualFields = array('item_count' => 'count(Item.id)');
    
        function getCountForSection($sectionId)
        {
            $ca = $this->Catalogitem->find
                (
                    'all',
                    array
                    (
                        'fields' => array('Catalogitem.id'),
                        'conditions' => array('Catalogitem.section_id' => $sectionId),
                        'recursive' => -1
                    )
                );
    
            $ca = Set::extract('/Catalogitem/id', $ca);
    
            $ret = $this->find
                (
                    'all',
                    array
                    (
                        'fields' => array('Item.catalogitem_id', 'item_count'),
                        'conditions' => array('Item.catalogitem_id' => $ca),
                        'group' => array('Item.catalogitem_id'),
                        'recursive' => -1
                    )
                );
    
            return $ret;
        }
    }
    

    Then simply use it in your controller:

    $ret = $this->Item->getCountForSection(1);
    debug($ret);
    

    How does it work:

    • Define a virtual field (cake 1.3+ only AFAIK) which will count items
    • Fetch all the Catalogitems belonging to a Section you're interested in
    • Use Set::extract() to get the Catalogitems in a simple array
    • Use the array of Catalogitems to filter Items while counting and grouping them

    NB: You don't seem to be using Cake's naming conventions in your database. This may hurt you.


    Sorry, in my first answer I somehow missed your GROUP BY requirement, which was the whole point of the question, I now realize. I haven't used this yet, but I came across it recently, and it looks like it might accomplish what you are looking for: Linkable Behavior.

    http://planetcakephp.org/aggregator/items/891-linkable-behavior-taking-it-easy-in-your-db

    Like Containable, but works with only right and left joins, produces much more compact queries and supports GROUP BY.

    http://github.com/rafaelbandeira3/linkable


    @azv

    Would this work for you:

    $section_id = 5;
    $fields     = array('CatalogItem.id as CatalogItemId', 'count(*) AS SectionCount');
    $conditions = array('Section.id' => $section_id);
    $joins      = array(
        array('table' => 'catalogitem',
              'alias' => 'CatalogItem',
              'type' => 'LEFT',
              'conditions' => array('Section.id' => 'CatalogItem.section_id')
        ),
        array('table' => 'item',
              'alias' => 'Item',
              'type' => 'LEFT',
              'conditions' => array('Item.catalogitem_id' => 'CatalogItem.id')
    ));
    
    $data = $this->Section->find('all',
                      array('fields' => $fields,
                            'conditions' => $conditions,
                            'joins' => $joins,
                            'group' => 'CatalogItem.id',
                            'recursive' => -1)
             );
    
    // access your data values
    foreach ($data['Section'] as $i => $datarow) {
        $catalogitem_id = $datarow['CatalogItemId'];
        $section_count  = $datarow['SectionCount'];
    }
    

    This way you are explicitly setting your joins and doing it all in one query. See here for more info on joins in Cake:

    http://book.cakephp.org/view/1047/Joining-tables

    Hope this helps. All the best,
    -s_r

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