31. Filters

New in version 2.2.

Doctrine 2.2 features a filter system that allows the developer to add SQL to the conditional clauses of queries, regardless the place where the SQL is generated (e.g. from a DQL query, or by loading associated entities).

The filter functionality works on SQL level. Whether a SQL query is generated in a Persister, during lazy loading, in extra lazy collections or from DQL. Each time the system iterates over all the enabled filters, adding a new SQL part as a filter returns.

By adding SQL to the conditional clauses of queries, the filter system filters out rows belonging to the entities at the level of the SQL result set. This means that the filtered entities are never hydrated (which can be expensive).

31.1. Example filter class

Throughout this document the example MyLocaleFilter class will be used to illustrate how the filter feature works. A filter class must extend the base Doctrine\ORM\Query\Filter\SQLFilter class and implement the addFilterConstraint method. The method receives the ClassMetadata of the filtered entity and the table alias of the SQL table of the entity.

Note

In the case of joined or single table inheritance, you always get passed the ClassMetadata of the inheritance root. This is necessary to avoid edge cases that would break the SQL when applying the filters.

Parameters for the query should be set on the filter object by SQLFilter#setParameter(). Only parameters set via this function can be used in filters. The SQLFilter#getParameter() function takes care of the proper quoting of parameters.

<?php
namespace Example;
use Doctrine\ORM\Mapping\ClassMetaData,
    Doctrine\ORM\Query\Filter\SQLFilter;

class MyLocaleFilter extends SQLFilter
{
    public function addFilterConstraint(ClassMetadata $targetEntity, $targetTableAlias)
    {
        // Check if the entity implements the LocalAware interface
        if (!$targetEntity->reflClass->implementsInterface('LocaleAware')) {
            return "";
        }

        return $targetTableAlias.'.locale = ' . $this->getParameter('locale'); // getParameter applies quoting automatically
    }
}

31.2. Configuration

Filter classes are added to the configuration as following:

<?php
$config->addFilter("locale", "\Doctrine\Tests\ORM\Functional\MyLocaleFilter");

The Configuration#addFilter() method takes a name for the filter and the name of the class responsible for the actual filtering.

31.3. Disabling/Enabling Filters and Setting Parameters

Filters can be disabled and enabled via the FilterCollection which is stored in the EntityManager. The FilterCollection#enable($name) method will retrieve the filter object. You can set the filter parameters on that object.

<?php
$filter = $em->getFilters()->enable("locale");
$filter->setParameter('locale', 'en');

// Disable it
$filter = $em->getFilters()->disable("locale");

Warning

Disabling and enabling filters has no effect on managed entities. If you want to refresh or reload an object after having modified a filter or the FilterCollection, then you should clear the EntityManager and re-fetch your entities, having the new rules for filtering applied.

Fork me on GitHub