CakePHP Unit belongsTo Complex, but not all Unit has Complex? - cakephp-2.0

Question

I have a 'Complex' model which hasMany Unit. My model associations are correct, everything works, it's just that I am having trouble getting a different model/association working correctly and it has made me wonder if I need to set this model up differently.
See, not ALL Unit will have a Complex associated with it. Some Unit are houses, some Unit are hotel rooms, and some Unit are just rental companies.
Because Complexes haveMany Units I am tempted to leave it alone, but I am wondering if I shouldn't redefine the relationship as Complex belongingTo Unit. I am trying to not repeat myself in my database with adding in multiple instances of the same complex.
Here is my current Unit Model:
class Unit extends AppModel {
public $name='Unit';
public $belongsTo=array(
'User'=>array(
'className'=>'User',
'foreignKey'=>'user'
),
'Complex'=>array(
'className'=>'Complex',
'foreignKey'=>'complex_id'
)
);
public $hasOne=array(
'Location'=>array(
'className'=>'Location',
'foreignKey'=>'location_id'
)
);
}
and here is my current Complex model:
class Complex extends AppModel {
public $name='Complex';
public $hasMany=array('Unit');
public $hasOne=array(
'Location'=>array(
'className'=>'Location',
'foreignKey'=>'location_id'
)
);
}
By the way, 'Location' is the model I am having trouble with (the Location part of my array currently returns empty when I call my unit/complex information in my view, so I need to get my association right).
If the Unit is a condo with a complex, I want it to return the Location of Complex. If it is a house or hotel or rental company, I want it to return the Location of Unit. I have to do several of these associations (images, location, and so forth) so I want to get everything straight right up front.
Is my current relationship between Unit and Complex correct or do I need to define everything differently?
UPDATE Here is my controller logic:
$this->paginate['Unit']=array(
'limit'=>9,
'order' => 'RAND()',
'contain'=>array(
'User'=>array(
'email'),
'Complex'=>array(
'id','complex_name', 'realname', 'photo1','photo2','photo3','photo4','photo5'),
'Location'=>array(
'complex_id','address', 'city','state','zip','area_code','exchange','sln','lat','lon','website')
),
'conditions'=>array(
'Unit.type'=>array('condo', 'rentalco'),
'Unit.active'=>1)
);
$data = $this->paginate('Unit');
$this->set('allcondos', $data);
}
And you can see the result I get here:
I am not currently interested in displaying a view of all Complexes, but the index page logic does have ContainableBehavior limited to just Complex(as originally I was going to have views for various Complexes):
public function index() {
$this->Complex->Behaviors->attach('Containable');
$this->Complex->contain();
$c=$this->Complex->find('all');
$this->set('complexes', $c);
}
UPDATE I have it working now, for anyone who encounters this problem. I had to change Location to the root and make Complex belongTo Location. Here are my models updated:
class Location extends AppModel {
public $name='Location';
public $hasMany=array('Complex', 'Unit');
var $belongsTo=array(
'Restaurant'=>array (
'className'=>'Restaurant',
'foreignKey'=>'restaurant_id'
)
);
}
class Complex extends AppModel {
public $name='Complex';
public $hasMany=array('Unit');
public $hasOne=array('Image');
public $belongsTo=array(
'Location'=>array(
'className'=>'Location',
'foreignKey'=>'location_id'
)
);
}
class Unit extends AppModel {
public $name='Unit';
public $belongsTo=array(
'User'=>array(
'className'=>'User',
'foreignKey'=>'user'
),
'Complex'=>array(
'className'=>'Complex',
'foreignKey'=>'complex_id'
),
'Location'=>array (
'className'=>'Location',
'foreignKey'=>'location_id'
),
);
public $hasOne=array('Image');
}
Many thanks to Wylie for the help, this was a doozy!

Answer 1

http://book.cakephp.org/2.0/en/core-libraries/behaviors/containable.html?containing-deeper-associations#containing-deeper-associations
When using ‘fields’ and ‘contain’ options - be careful to include all foreign keys that your query directly or indirectly requires. Please also note that because Containable must to be attached to all models used in containment, you may consider attaching it to your AppModel.
You can do that in your AppModel like this: public $actsAs = array('Containable');
You don't have to use Contain when you don't want to so it shouldn't get in the way.
When a model A has model B, you use the foreign key within model B. So your foreign key on the Location should be complex_id. Although, that shouldn't be so because not all units have a complex.
It seems to me you should make the Location the "root". So, Complex belongsTo Location and Unit belongsTo Complex and Location. Then Location hasOne/Many complex, etc. Either that or just put the address columns in the Unit/Complex tables.