Symfony2查询具有订单的特定数量的对象

Question

I want to know if it is possible to query only a specific amount of objects and order them. For example I want to query for the newest products added, and I want to get only the newest 10 products from the table.

I dont know if you can order a specific amount in the controller, but I know that you can do slice in the twig. However getting the right amount straight from the query would be much more sufficient if possible.

However for some reason I cant even sort the product that I get(http://symfony.com/doc/current/book/doctrine.html#fetching-objects-from-the-database). The documentation clearly shows that you can easily order objects. However with my code it does not order:

        $newProducts = $em->getRepository('MpShopBundle:Product')->findBy(array(), array('id' => 'DESC'));

This returns all of the products. How to query for only 10 of all of them?

How can I achieve what I want?

Answer 1

You can add more parameters to the findBy()-method like:

$newProducts = $em->getRepository('MpShopBundle:Product')->findBy(
    array('foo' => 'bar'),
    array('id' => 'ASC'),
    10,
    0
);

The signature of this method:

/**
 * Finds entities by a set of criteria.
 *
 * @param array      $criteria
 * @param array|null $orderBy
 * @param int|null   $limit
 * @param int|null   $offset
 *
 * @return array The objects.
 */
public function findBy(array $criteria, array $orderBy = null, $limit = null, $offset = null)

Further reading: 7. Working with Objects / 7.8.2. By Simple Conditions

The EntityRepository#findBy() method additionally accepts orderings, limit and offset as second to fourth parameters.