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Filters
Doctrine ORM 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).
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.
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. |
- For the filter to correctly function, the following rules must be followed. Failure to do so will lead to unexpected results from the query cache.
-
- Parameters for the query should be set on the filter object by
SQLFilter#setParameter()
before the filter is used by the ORM ( i.e. do not set parameters insideSQLFilter#addFilterConstraint()
function ). - The filter must be deterministic. Don't change the values base on external inputs.
- Parameters for the query should be set on the filter object by
The SQLFilter#getParameter()
function takes care of the proper quoting of parameters.
1 <?php
namespace Example;
use Doctrine\ORM\Mapping\ClassMetadata,
Doctrine\ORM\Query\Filter\SQLFilter;
class MyLocaleFilter extends SQLFilter
{
public function addFilterConstraint(ClassMetadata $targetEntity, $targetTableAlias): string
{
// Check if the entity implements the LocalAware interface
if (!$targetEntity->reflClass->implementsInterface('LocaleAware')) {
return "";
}
return $targetTableAlias.'.locale = ' . $this->getParameter('locale'); // getParameter applies quoting automatically
}
}
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If the parameter is an array and should be quoted as a list of values for an IN query
this is possible with the alternative SQLFilter#setParameterList()
and
SQLFilter#getParameterList()
functions.
Configuration
Filter classes are added to the configuration as following:
The Configuration#addFilter()
method takes a name for the filter and the name of the
class responsible for the actual filtering.
Disabling/Enabling Filters and Setting Parameters
Filters can be disabled and enabled via the FilterCollection
which is
stored in the EntityManager
. The FilterCollection#enable($name)
method
will retrieve the filter object. You can set the filter parameters on that
object.
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. |