Question

For some models, we have soft deletion implemented using a valid boolean in MySQL.

In the class, the scopes method is defined as follows:

public function scopes() {
    return array(
        'valid'=>array(
            'condition'=>"t.valid=1",
        )
    );
}

This is so that when we load a model we can call the scope to make it include only valid (not deleted) models alongside the other find criteria, or whatever it happens to be.

This isn’t very DRY and I am wondering if there is an alternative way of achieving the same thing, that could perhaps be applied to an interface, the abstract Model class that all models derive from, or, if using 5.4, a trait.

Answer 1

Yii has a feature called Behaviors
that is similar to php 5.4 traits but works with earlier versions too.

SoftDeleteBehavior.php:

class SoftDeleteBehavior extends CActiveRecordBehavior {
    public $deleteAttribute = 'valid';
    public $deletedValue = 0;

    public function beforeDelete($event) {
        if ($this->deleteAttribute !== null) {
            $this->getOwner()->{$this->deleteAttribute} = $this->deletedValue;
            $this->getOwner()->update(array($this->deleteAttribute));

            // prevent real deletion of record from database
            $event->isValid = false;
        }
    }

    /**
     * Default scope to be applied to active record's default scope.
     * ActiveRecord must call this from our own default scope.
     * @return array the scope to be applied to default scope
     */
    public function defaultScope() {
        return array(
            'condition' => $this->getOwner()->getTableAlias(false,false).'.'.$this->deleteAttribute
                . ' <> '.var_export($this->deletedValue, true),
        );
    }
}

Then i have this class to apply deafultscope from behaviors:
ActiveRecord.php (i ofcourse have more methods in this class, downside is that you need to call parent method if you need to extend the method):

class ActiveRecord extends CActiveRecord {

    public function defaultScope() {
        $scope = new CDbCriteria();

        foreach ($this->behaviors() as $name => $value) {
            $behavior = $this->asa($name);
            if ($behavior->enabled && method_exists($behavior,'defaultScope')) {
                $scope->mergeWith($behavior->defaultScope());
            }
        }



        return $scope;
    }
}

And then you use it in your Models:

class MyModel extends ActiveRecord {
    public function behaviors() {
        return array(
            'SoftDeleteBehavior' => array(
                'class' => 'application.components.behaviors.SoftDeleteBehavior',
            ),
        );
    }
}

PROTIP: you can specify your own ActiveRecord class when you generate models with gii