Question

I am getting started with Symfony2 and I am trying to understand the Form Component. I am looking at this page http://docs.symfony-reloaded.org/guides/forms/overview.html

And I can understand how we create form classes but what is confusing is how we actually use those forms in our controller.

$form = ContactForm::create($this->get('form.context'));

Does anyone have a more in depth explanation of the form.context portion of this code, and the actual process behind using forms within controllers?

Thanks.

Answer 1

form.context service is a Symfony\Component\Form\FormContext object by default. Here’s a full definition of this service:

    <service id="form.context" class="%form.context.class%">
        <argument type="collection">
            <argument key="validator" type="service" id="validator" />
            <argument key="validation_groups">%form.validation_groups%</argument>
            <argument key="field_factory" type="service" id="form.field_factory" />
            <argument key="csrf_protection">%form.csrf_protection.enabled%</argument>
            <argument key="csrf_field_name">%form.csrf_protection.field_name%</argument>
            <argument key="csrf_provider" type="service" id="form.csrf_provider" />
        </argument>
    </service>

Actually it’s a very simple object that just prepare some basic options used by almost every form, ie. a validator, CSRF protection and field factory.

In fact the code you’ve posted is equivalent of:

$form = new \Symfony\Components\Form\Form(null, array(
    'validator' => $this->get('validator'),
    'validation_groups' => ...
    ...
));