HABTM with Pagination - php

Question

At first take a look at the following model structure:
Model Building:
id
name
Model BuildingRange:
id
building_id
postalcode
Ok, so BuildingRange $belongsTo Building and Building $hasMany BuildingRange. Should be clear til' here.
Now let
$current_postalcode="12345";
I know want to do something like this in the BuildingController:
$this->paginate('Building',array('Building.BuildingRange.postalcode'=>$current_postalcode));
In text: I want to select all buildings for that an entry "BuildingRange" with $current_postalcode exists. How do you do that?
I appreciate your help!

Answer 1

When dealing with such a hasMany association, CakePHPs auto-magic needs two queries, one on the Building table, and one on the BuildingRange table. When passing conditions via the pagiante method, these conditions will be passed to the first query, and thus this it will fail since the associated models table isn't joined.
This problem can be solved on a few different ways, one would be using an ad-hoc join, for example:
$this->paginate = array
(
'joins' => array
(
array
(
'table' => 'building_ranges',
'alias' => 'BuildingRange',
'type' => 'LEFT',
'conditions' => array('BuildingRange.building_id = Building.id')
)
)
);
$this->paginate('Building', array('BuildingRange.postalcode' => $current_postalcode));
This would result in a query that looks something like this:
SELECT `Building`.`id`,
`Building`.`name`
FROM `buildings` AS `Building`
LEFT JOIN `building_ranges` AS `BuildingRange`
ON ( `BuildingRange`.`building_id` = `Building`.`id` )
WHERE `BuildingRange`.`postalcode` = '12345'
LIMIT 20
Note that in the conditions passed to the paginate method there is no need to reference the BuildingRange model through the Building model, ie no need to use Builduing.BuildingRange (that wouldn't work anyway).
ps, it's always good to mention the CakePHP version you are using!