Using count subquery within CakePHP ORM - mysql

Question

I'm looking through the CakePHP docs and I can't see anywhere that explains how you execute a subquery in the MySQL statement. I would essentially like to count the number of credits each user has as a field, but at the moment it is counting the credits cumulatively for all users into one field:
$this->Users->find()
->contain(['Plans','Products'])
->contain('Credits', function ($q) {
return $q->select(['count' => $q->func()->count('*')]);
})->group(['Users.id']);
The query I'm trying to create is more like :
SELECT *, (SELECT COUNT(*) FROM credits Credits WHERE Credits.user_id = Users.id) as credit_count FROM users Users group by Users.id ASC

Answer 1

Contained hasMany associations will always be retrieved in a separate query, and that is where the conditions will be applied that you are defining in the contain callback (check Sql Log tab of DebugKit).
To get the results that you are looking for requires to either join in the association, and counting the Credits in the same query, something like this:
$this->Users
->find()
->select(function(\Cake\ORM\Query $q) {
return ['count' => $q->func()->count('Credits.id')]
})
->select($this->Users)
->contain(['Plans','Products'])
->leftJoinWith('Credits')
->group(['Users.id']);
or to explicitly use a subquery, which works by simply creating a regular query object, and passing it to wherever the query builder accepts expression objects, for example as the value in your select list:
$subquery = $this->Users->Credits
->find()
->select(function(\Cake\ORM\Query $q) {
return ['count' => $q->func()->count('Credits.id')]
})
->where(function (\Cake\Database\Expression\QueryExpression $exp) {
return $exp->equalFields('Credits.user_id', 'Users.id'):
});
$this->Users
->find()
->select(['count' => $subquery])
->select($this->Users)
->contain(['Plans','Products']);
See also
Cookbook > Database Access & ORM > Query Builder > Selecting Specific Fields
Cookbook > Database Access & ORM > Query Builder > Advanced Conditions