Doctrine+MongoDB - How to query for documents with array that's not empty

Question

I would like to receive all the documents with array "likes" with size greater than zero. I saw an example of using the ->size() method to get an array in a specific size:

$qb = $dm->createQueryBuilder('Article')->field('comments')->size(0);

but not to get an array with size different than zero, is there an option to do that?

Thank you!

Answer 1

You can pass specific positive integers to size, but you cannot use it to query ranges. This is not a limitation of Doctrine but of MongoDB. The docs on $size say:

$size does not accept ranges of values. To select documents based on fields with different numbers of elements, create a counter field that you increment when you add elements to a field.

To do this, add a $comments_count @Int field to Article and update it either a) in document methods which modify $comments or b) in a document method annotated with @PreUpdate.

Another (inefficient) option is to use where with a javascript expression:

$where = "function() { return this.comments && this.comments.length > 0; }";
$qb = $dm->createQueryBuilder('Article')->field('comments')->where($where);