Symfony2/Doctrine How to store count of related objects within an Entity

Question

I have set up a bundle that has a test object which holds a number of testQuestion objects each of which is a question and the given answer (or 0 if no answer). From twig I want

Answer 1

There are a number of different patterns you can use to achieve this result, the simplest of which is to simply use an aggregate field. This stores the information after it's modified, rather than calculating it each time that it's needed.

An alternate solution is to create a one-to-many association between your Test and TestQuestion repositories (assuming that there isn't one already), then in your twig template you can simply use {{ testEntity.questionsAnswered.count() }} - you can even tell Doctrine to make this an "extra-lazy" association so that it uses the COUNT SQL statement to look up how many answered questions there are (by default it actually fetches the question entities when you try to enumerate the association).

Finally, there's the method that I wouldn't recommend highly, but might be required depending on your situation. Similar to the approach that you use in your question, you fetch the question count in your repository, but to keep with Symfony's simple Model approach, you don't kick off the query from inside the entity (as the entity should never have information about the entity manager/repository).

Instead, you can use a Doctrine EventListener to be informed whenever an instance of your Test entity is loaded (see here, using the postLoad event), then call your repository method and set it on the entity from there.