php - How to select distinct query using symfony2 doctrine query builder?

Question

I have this symfony code where it retrieves all the categories related to a blog section on my project:

$category = $catrep->createQueryBuilder('cc')
    ->Where('cc.contenttype = :type')
    ->setParameter('type', 'blogarticle')
    ->getQuery();

$categories = $category->getResult();

This works, but the query includes duplicates:

Test Content
Business
Test Content

I want to use the DISTINCT command in my query. The only examples I have seen require me to write raw SQL. I want to avoid this as much as possible as I am trying to keep all of my code the same so they all use the QueryBuilder feature supplied by Symfony2/Doctrine.

I tried adding distinct() to my query like this:

$category = $catrep->createQueryBuilder('cc')
    ->Where('cc.contenttype = :type')
    ->setParameter('type', 'blogarticle')
    ->distinct('cc.categoryid')
    ->getQuery();

$categories = $category->getResult();

But it results in the following error:

Fatal error: Call to undefined method DoctrineORMQueryBuilder::distinct()

How do I tell symfony to select distinct?

Answer 1

This works:

$category = $catrep->createQueryBuilder('cc')
        ->select('cc.categoryid')
        ->where('cc.contenttype = :type')
        ->setParameter('type', 'blogarticle')
        ->distinct()
        ->getQuery();

$categories = $category->getResult();

Edit for Symfony 3 & 4.

You should use ->groupBy('cc.categoryid') instead of ->distinct()