Lost column definitions with joins, in twig - symfony

Question

I've got a query set up in doctrine that I'm confident does what it's supposed to...it joins several tables so we can skip a bunch of extra queries to get data through foreign keys:
$posts = $this->getDoctrine()->getManager()
->createQuery('
SELECT a AS article, COUNT(c) AS comments
FROM ArticleBundle:Article a
LEFT JOIN CommentsBundle:Comment c WITH (c.article = a.id)
LEFT JOIN ImageBundle:Image i WITH (i.id = a.image)
GROUP BY a.id
ORDER BY a.timestamp DESC
')
->getResult();
I'm able to access the data quite succesfully, like so:
{% for post in posts %}
<div id="news-story">
<div class="title">{{ post.article.title }}</div>
<div class="comments">{{ post.comments }}</div>
...
{% endfor %}
The issue is, as soon as I add a second column ("i AS image") to the field list, it fails. I get the following message...
Item "article" for "Array" does not exist in ...
...and I can't quite figure out why. I would hope that I would be able to access the variables like {{ post.article.title }} and {{ post.image.path }} (which does exist, by the way)...but I can't.
Any thoughts would be greatly appreciated.
Thanks!

Answer 1

I think your confusion arises from the fact that you have created a query that returns a scalar result: COUNT(c)... along with objects.
This means that instead of returning an array of Article entities, as you expect (you are trying to use post.image) you actually get an associative array, where each member contains the count - post.comments and the article entity post.article.
n.b. If you want to access images associated with the article, you will need to use post.article.image.
I'll try and illustrate:
Your expecting an array of article objects that you can iterate over:
array(
[0] => ArticleEntity,
[1] => ArticleEntity,
[2] => ArticleEntity
)
What you actually get from your query
array(
[0] => array(
'article' => ArticleEntity,
'comments'=> 10
),
[1] => array(
'article' => ArticleEntity,
'comments'=> 3
),
[2] => array(
'article' => ArticleEntity,
'comments'=> 0
)
)
If you remove the scalar part of your query COUNT(c) AS comments then you will get the first example, leave it in and you will get the second example.
The Doctrine documentation on pure/mixed results is some good reading/explanation on this.
As a side note is there any reason you are writing raw SQL. For a start you can re-write the query using DQL to leverage some of the power Doctrine offers.
$qb = $this->getDoctrine()->getManager()->createQueryBuilder();
$qb
->select('article', 'image', 'COUNT(comments) as comment_count')
->from('ArticleBundle:Article', 'article')
->leftJoin('article.comment', 'comments')
->leftJoin('article.image', 'image')
->groupBy('article.id')
->orderBy('article.timestamp', 'DESC')
;
$posts = $qb->getQuery()->getResult();