Working with Virtual Fields when using model alias - cakephp

Question

I'm a CakePHP newbie. I have been looking for an answer to this for a while.
I followed directions from RichardAtHome in answer regarding autocomplete in CakePHP (autoComplete CakePHP 2.0).
I set up the function in my AppController.
This works very well with real fields but bugged when using Virtual Fields:
class Person extends AppModel {
public $virtualFields = array(
'name' => "CONCAT(Person.firstname, ' ', Person.lastname)"
);
}
I get this error: Column not found: 1054 Unknown column 'Person.name' in 'where clause'
When checking the SQL query I see this:
(CONCAT(`Person`.`firstname`, ' ', `Person`.`lastname`)) AS `Person__name`
This problem only occurs when I use $model = $this->{$this->modelClass}->alias;. Hardcording the model class in a specific controller (not AppController) works fine.
What do I need to do to make it work?
UPDATE:
After fiddling with this I discovered that it doesn't relate to $model = $this->{$this->modelClass}->alias; at all.
Instead I changed the 'conditions' value in the find() method and it all worked out fine. I am still puzzled as to why, but now it works just fine.
Incorrect code:
$result = $this->$model->find('all', array(
'conditions' => array(
$model . '.' . $field . " LIKE '%" . $term . "%'"
)
));
Correct code:
$result = $this->$model->find('all', array(
'conditions' => array(
$model . '.' . $field . " LIKE " => "%" . $term . "%"
)
));

Answer 1

That is an issue of the CakePHP core. You can't use a variable or another property within the declaration of a property. So you have to override the constructor and set your virtual fields there using $this->alias. The core has no automatic way to handle this internally so you have to take care of it.
The issue applies to all model properties by the way. We had the same issue with the $order property of the model. I'll paste the code here but you will have to modify the aliasPrefixing() method to not just go by the start of a string. Replace it by a regex and you should be fine to apply the prefix replacing method to all properties.
/**
* Constructor
*
* #param integer|string|array $id Set this ID for this model on startup, can also be an array of options, see above.
* #param string $table Name of database table to use.
* #param string $ds DataSource connection name.
*/
public function __construct($id = false, $table = null, $ds = null) {
parent::__construct($id, $table, $ds);
$this->prefixOrderProperty();
}
/**
* Prefixes the order property with the actual alias if its a string or array
*
* The core fails on using the proper prefix when building the query with two
* different tables. Already reported this to the core team and might work on a
* core patch to fix this in the DboSource. The core fix should be done in DboSource,
* when reading the order property from the model.
*
* #return void
*/
public function prefixOrderProperty() {
if (is_string($this->order)) {
$this->order = $this->aliasPrefixing($this->order);
}
if (is_array($this->order)) {
foreach ($this->order as $key => $value) {
$this->order[$key] = $this->aliasPrefixing($value);
}
}
}
/**
* Checks if a string of a field name contains a dot if not it will add it and add the alias prefix
*
* #param string
* #return string
*/
public function aliasPrefixing($string) {
if (stripos($string, '.') === false) {
return $this->alias . '.' . $string;
}
return $string;
}