CakePHP: Joining calculated fields from another model to a model - php

Question

I've been trying to figure out how to add some computed fields to a model in CakePHP. I'm able to achieve the desired result with the following query:
SELECT project_id,
COUNT(*) AS clicks_total,
SUM(CASE WHEN clicks.redirect_url = projects.url THEN 1 ELSE 0 END) AS clicks_redirected,
SUM(CASE WHEN clicks.redirect_url = projects.url THEN 0 ELSE 1 END) AS clicks_not_redirected
FROM clicks
LEFT JOIN projects ON clicks.project_id = projects.id
GROUP BY project_id
If I attempt to execute it as a custom query Cake transforms the result in such a way that it would require much array manipulation to be usable. I tried to do it the Cake way with the following code, but for some reason the calculated fields end up in a separate array which causes strange behavior in the view:
$this->paginate = array(
'Project' => array(
'fields' => array(
'id', 'name', 'url', 'url_mac', 'url_mobile',
'COUNT(*) AS clicks_total',
'SUM(CASE WHEN Click.redirect_url = Project.url THEN 1 ELSE 0 END) AS clicks_redirected',
'SUM(CASE WHEN Click.redirect_url = Project.url THEN 0 ELSE 1 END) AS clicks_not_redirected'
),
'joins' => array(
array(
'table' => 'clicks',
'alias' => 'Click',
'type' => 'LEFT',
'conditions' => array('Click.project_id = Project.id')
)
),
'group' => 'project_id'
));
$this->set('projects', $this->paginate());
Produces the following result:
array(
(int) 0 => array(
'Project' => array(
'id' => '508705c8-126c-48f9-bd9a-6d79d13bb9ea',
'name' => 'Test Project',
'url' => 'http://www.test.com',
'url_mac' => 'http://www.mac.com',
'url_mobile' => 'http://www.mobile.com'
),
(int) 0 => array(
'clicks_total' => '80',
'clicks_redirected' => '35',
'clicks_not_redirected' => '45'
)
),
(int) 1 => array(
'Project' => array(
'id' => '508b1073-2aa8-4895-b8d9-152ed13bb9ea',
'name' => 'Another Project',
'url' => 'http://another.com',
'url_mac' => 'http://anothermac.com',
'url_mobile' => 'http://anothermobile.com'
),
(int) 0 => array(
'clicks_total' => '134',
'clicks_redirected' => '70',
'clicks_not_redirected' => '64'
)
)
)
Does anyone have any ideas for getting the calculated click counts to show up under the Project array?

Answer 1

You can add virtual fields to your model:
Check it out: http://book.cakephp.org/1.3/view/1608/Virtual-fields
In Project model:
public $virtualFields = array('clicks_total' => 'COUNT(*)');