Manipulate form between submission and validation

Question

Using Symfony2 for a little while now, I ran into a problem on my current development : I need to edit the data sent by a form before it gets validated. Here's the situation :

• My form contains two important fields : "name" and "domain".
• "domain" refers to an entity, which has a property "domain_name".

Now, imagine "name" is set to "mywebsite" (using the form), and that the domain is set to "mydomain.com" (entity field selecting domains in a database) :

• form[name] : "mywebsite"
• form[domain] : Object (domain_name => "mydomain.com")

What I want to achieve is to change the value of the "name" field according to the selected domain. I want to append "domain_name" to "name", in order to get :

• form[name] : "mywebsite.mydomain.com"
• form[domain] : Object (domain_name => "mydomain.com")

I found 2 solutions but they don't seem to fit the situation :

• Data transformers. Seems to work on one field only, however, in order to edit "name", I need to access the "domain" entity from the form, which is not available in the Data Transformer class. What I may be looking for is a way to apply a data transformer on the whole form (but I didn't find a way to do this...)
• Form events. This will edit the "name" field before submission, but I want my modifications to happen after (this way, the user cannot alter them).

Is there a solution I've missed ?

Answer 1

You can modify submitted data in form.PRE_BIND event. This event occurs then you call $form->bind($request) in controller. How to add event subscriber to form. Keep in mind that you have to deal with bare data that is not converted to entities etc.

Applying Data Transformer to entire form very easy - just dont specify field. For example

$builder
    ->add('name', 'text')
    ->add('domain', 'entity')
    ->addModelTransformer($transformer);

vs

// add a normal text field, but add your transformer to it
$builder->add(
    $builder->create('name', 'text')
        ->addModelTransformer($transformer)
);