Symfony 2, how to persist join table entities? - symfony

Question

This is such a trivial problem that I can't believe I couldn't find an answer.
Symfony 2, doctrine 2.1. I've got two entities and one intermediate entity (join table). User, Pref, and UsersPrefs. Pref table is dictionary table, so that I could change pref name in one place only. Ok, let's see the picture:
infographic http://dl.dropbox.com/u/22495762/infographic.png
As You can see, I want to have a checkbox group, with all the possible choices (prefs) and preferred choices checked. So, if there are 3 prefs, and only 2 selected by the user, there should be 3 checkboxes, 2 selected.
It's simple, if done plain PHP - query database twice to get list of all prefs and user prefs, render checkboxes depending on values, add some actions to handle form submit, done.
But for the life of God I can't get this to work using symfony & doctrine. I was able to get to the point where I can update relationships in doctrine and further in database, but I'm using raw query values for that:
$data = $request->request->get('some_form');
and this supposedly isn't the way it should be done?
Morevoer, I'm completely stuck as to how should I display checkbox list. I either get list of all options, none checked, or only user options, all checked. Or 'left joined' result set with checkboxes for all cases, useless anyway.
I've come to the point where I tried to overload twig checkbox template, but I couldn't pass variables to the form template, and that was the last straw...
EDIT:
This way I'm getting group of checkboxes, not connected to user choices:
->add('prefs', 'entity', array(
'class' => 'Some\TestBundle\Entity\Pref',
'expanded' => 'true',
'multiple' => 'true',
'property' => 'name'
))
And this way I'm getting only user choices, all checked:
->add('prefs', 'entity', array(
'class' => 'Some\TestBundle\Entity\UserPrefs',
'multiple' => 'false',
'expanded' => 'false',
'property' => 'pref.name',
'query_builder' => function(EntityRepository $er) use ($id) {
return $er->createQueryBuilder('u')
->where("u.user = :id")
->setParameter('id', $id)
;
},
))
And I tried left joins and other options, but at best I could get list of all possible options for all possible users, checked accordingly.
EDIT (POSSIBLE SOLUTION):
I'm displaying checkbox group:
->add('pref_ids', 'choice', array(
'choices' => array(
'1' => 'pref one',
'2' => 'pref two',
'3' => 'pref three',
),
'expanded' => 'true',
'multiple' => 'true'
))
I've added $pref_ids array in User entity. Now I just need to set values in array according to preferences chosen by user:
public function setPrefIds()
{
$prefs = $this->getPrefs();
$this->pref_ids = array();
foreach($prefs as $pref){
array_push($this->pref_ids, $pref->getPref()->getId());
}
return $this;
}
This way I get appropriate checkboxes checked.
Writing values to database is reversal of the process. I'm getting input values from request:
$data = $request->request->get('edit_form');
var_dump($data['pref_ids']);
Removing all user prefs:
foreach ($userPrefs as $pref){
$em->remove($pref);
}
And setting actual associations in doctrine from ids:
$entity->setPrefsById($em, $data['pref_ids']);
Here I'm passing entity manager to entity itself, but I need to refactor it, because it looks kinda messy this way.
Then $em->flush(); and that's it.
That's the best I could come up with. Probably it's overcomplicated and should be done entirely different way. Unfortunately couldn't figure out this "other way".

Answer 1

You need the choice field type: http://symfony.com/doc/current/reference/forms/types/choice.html
In your builder, it will be something like
$builder->add('prefs', 'choice', array('multiple' => true, 'expanded' => true, 'choices' => fetch the available prefs from the database here);
Edit: Sorry I'm mistaken, you need the "Entity" type, which fetches automatically the choices from the database: http://symfony.com/doc/current/reference/forms/types/entity.html
You must still put multiple => true expanded => true to get checkboxes.