Leave out discriminator part of Doctrine' generated SQL

问题

Assume the following AbstractPage model:

/*
 *     @ORM\Entity
 *     @ORM\Table(name="page")
 *     @ORM\InheritanceType("SINGLE_TABLE")
 *     @ORM\DiscriminatorColumn(name="type", type="string")
 *     @ORM\DiscriminatorMap
 *     ({
 *         "page" = "Page",
 *         "link" = "Link"
 *     })
 */

And the following DQL query:

SELECT p FROM \Page\Model\AbstractPage

The generated SQL will be:

SELECT ... FROM page p0_ WHERE p0_.type IN ('page', 'link')

Now to the question: how can I remove the WHERE clause from this query. On more complex queries this part of the WHERE clause makes it not possible to use some indexes that are defined. This can be resolved by adding type to the indexes, but this makes my indexes larger and I feel this is not necessary.

The AbstractPage is the root in the inheritance tree. Thus we are interested in ALL records in the table. Omiting the WHERE part does precisely that.

So the question is: how can I make Doctrine remove this WHERE part where it is not necessary.

Thanks!

回答1:

Here is the solution I can think out. The idea is to extend some doctrine classes to add functionality required. Keep models as they are now.

Create new class extending SqlWalker (update namespaces of course)

<?php

namespace Sad;


use Doctrine\ORM\Mapping\ClassMetadata;
use Doctrine\ORM\Query\SqlWalker;

class CustomSqlWalker extends SqlWalker
{

  const IGNORE_DISCRIMINATION = 'ignoreDiscrimination';

  /**
   * {@inheritdoc}
   */
  public function walkWhereClause($whereClause)
  {
    // Get list of aliases in which discrimination should be ignored
    $ignoreDescription = $this->getQuery()->getHint(self::IGNORE_DISCRIMINATION);
    if ($ignoreDescription !== false) {
      // For each aliases...
      foreach ($this->getQueryComponents() as $k => $component) {
        // ...check if alias is in ignore list
        if (in_array($k, $ignoreDescription)) {
          /** @var $metaObj ClassMetadata */
          $metaObj = $component['metadata'];
          // Update inheritance type to disable discrimination where
          if ($metaObj->isInheritanceTypeSingleTable()) {
            $metaObj->setInheritanceType(ClassMetadata::INHERITANCE_TYPE_NONE);
          }
        }
      }
    }
    return parent::walkWhereClause($whereClause);
  }
}

Then making query you do the following:

echo $entityManager->createQuery("SELECT p FROM \Sad\Schema\AbstractPage as p")->getSQL();
// Output: ELECT p0_.id AS id_0, p0_.name AS name_1, p0_.type AS type_2 FROM page p0_ WHERE p0_.type IN ('page', 'link')

$query = $entityManager->createQuery("SELECT p FROM \Sad\Schema\AbstractPage as p");
// Make sure query uses custom walker
$query->setHint(\Doctrine\ORM\Query::HINT_CUSTOM_OUTPUT_WALKER, 'Sad\CustomSqlWalker');
// Specify which aliases should ignore discrimination
$query->setHint(\Sad\CustomSqlWalker::IGNORE_DISCRIMINATION, array('p'));

echo $query->getSQL();
// Output: ELECT p0_.id AS id_0, p0_.name AS name_1, p0_.type AS type_2 FROM page p0_

来源：https://stackoverflow.com/questions/20396506/leave-out-discriminator-part-of-doctrine-generated-sql

标签

php

sql

doctrine-orm

indexing

dql