How to sort Symfony2 form collection items

Question

I have an entity Recipe with a form collection of steps assigned to.

The user is able to sort the steps with drag and drop and some javascript. To save the new order I added a field step_number to each step, which is then automatically filled by javascript.

To make sure that the steps are displayed in the right order I use @ORM\OrderBy({"step_number" = "ASC"}) in my Recipe entity.

The only problem is: if the user submits the form and has some errors, the form gets displayed again, but not in the right step order because they are not fetched from the database.

I tried to solve this by manually ordering the collection with an eventListener like this:

$builder->get('steps')->addEventListener(FormEvents::SUBMIT, function(FormEvent $event){
                $steps = $event->getData();

                $steps[1]->setStepnumber('8');//does not affect the rendered form
                $event->setData($steps);

                \Doctrine\Common\Util\Debug::dump($event->getData());
                //add some logic to sort the steps

});

This is what the dump looks like:

array(2) {
  [0]=>
  object(stdClass)#1212 (8) {
    ["__CLASS__"]=>
    string(29) "CoBo\RecipeBundle\Entity\Step"
    ["id"]=>
    int(244)
    ["recipe"]=>
    string(31) "CoBo\RecipeBundle\Entity\Recipe"
    ["step_number"]=>
    string(1) "2"
    ["description"]=>
    string(3) "test description 1"
  }
  [1]=>
  object(stdClass)#1220 (8) {
    ["__CLASS__"]=>
    string(29) "CoBo\RecipeBundle\Entity\Step"
    ["id"]=>
    int(245)
    ["recipe"]=>
    string(31) "CoBo\RecipeBundle\Entity\Recipe"
    ["step_number"]=>
    string(1) "8"
    ["description"]=>
    string(4) "test description 2"

  }
}

but the modification of $steps[1]->setStepnumber('8'); doesnt affect the rendered form. step[1] still has the old number. I dont know what I'm doing wrong here. A different approach of sorting the steps would be helpfull, too.

Answer 1

You should use FormEvents::PRE_SET_DATA instead. Because after FormEvents::POST_SUBMIT the data you set doesn't get set to the form data again. Therefore you don't see the changed data.

Please look at https://github.com/symfony/Form/blob/master/Form.php to see which form event is dispatched after which operations.

Also have a look at official form events documentation.

http://symfony.com/doc/current/components/form/form_events.html