How to set the rules depending on the entity field? - validation

Question

Situation
using Cake 3.2.6
in my CostItemsTable,
I have a buildRules function
/**
* Returns a rules checker object that will be used for validating
* application integrity.
*
* #param \Cake\ORM\RulesChecker $rules The rules object to be modified.
* #return \Cake\ORM\RulesChecker
*/
public function buildRules(RulesChecker $rules)
{
$rules->add($rules->existsIn(['foreign_model_id'], 'ForeignModels'));
return $rules;
}
What I want
My CostItems Entity has 2 fields called foreign_model and foreign_model_id.
foreign_model_id acts as the foreign key. foreign_model acts as the Table that will be Parent to the CostItems table.
so a typical record can have foreign_model as GeneralCostCategories and foreign_model_id as 1.
What I tried
I tried to log the $this inside the buildRules function but I find nothing useful that allows me to dynamically change this rule.
$rules->add($rules->existsIn(['foreign_model_id'], 'ForeignModels'));
to
$rules->add($rules->existsIn(['foreign_model_id'], $entity->foreign_model));

Answer 1

There are various ways to solve this, here's two of them.
* It should be noted that the following is all untested example code!
Custom rules
You could implement a custom rule, either as a callback, or as a rule class, where the entity is going to be passed to, and then run the exists check accordingly with the data from the entity.
callback
use Cake\Datasource\EntityInterface;
use Cake\ORM\Rule\ExistsIn;
// ...
$rules->add(
function (EntityInterface $entity, array $options) {
$check = new ExistsIn(['foreign_model_id'], $entity->get('foreign_model'));
return $check($entity, $options);
},
'_existsIn',
[
'errorField' => 'foreign_model_id',
'message' => __d('cake', 'This value does not exist')
]
);
custom rule class, src/Model/Rule/MyExitsIn.php
namespace App\Model\Rule;
use Cake\Datasource\EntityInterface;
use Cake\ORM\Rule\ExistsIn;
class MyExistsIn extends ExistsIn
{
public function __construct($fields)
{
parent::__construct($fields, null);
}
public function __invoke(EntityInterface $entity, array $options)
{
$this->_repository = $entity->get('foreign_model');
return parent::__invoke($entity, $options);
}
}
use App\Model\Rule\MyExistsIn;
// ...
$rules->add(
new MyExistsIn(['foreign_model_id']),
'_existsIn',
[
'errorField' => 'foreign_model_id',
'message' => __d('cake', 'This value does not exist')
]
);
Build rules on the fly
Or use the Model.beforeRules event, which receives the entity too, and modify the rules checker object on the fly.
in your table class
use Cake\Datasource\EntityInterface;
use Cake\Event\Event;
// ...
public function beforeRules(Event $event, EntityInterface $entity, \ArrayObject $options, $operation)
{
/* #var $rulesChecker \Cake\ORM\RulesChecker */
$rulesChecker = $this->rulesChecker();
$rulesChecker->add(
$rulesChecker->existsIn(['foreign_model_id'], $entity->get('foreign_model'))
);
}
See also
Cookbook > Database Access & ORM > Validation > Creating a Rules Checker
Cookbook > Database Access & ORM > Validation > Creating Custom Rule objects
Cookbook > Database Access & ORM > Table Objects > Lifecycle Callbacks > beforeRules