Question

How to reproduce this:

1. Create a collection of some type

<?php

$builder->add('foo', 'collection', array(
  'type'            => new BarType(),
  'allow_add'       => true,
  'allow_delete'    => true,
  'by_reference'    => false,
  'prototype'       => true,
  'prototype_name'  => 'this_is_prototype',
  'options'         => array(
      'data_class' => 'Acme\FooBundle\Entity\Bar'
    ),
));

2. Create BarType

<?php 

class BarType extends AbstractType
{
    public function buildForm(FormBuilderInterface $builder, array $options)
    {
        var_dump(array(
            $builder->getForm()->getName() => $builder->hasParent()
        ));
        $builder->add('bar', 'text'); 
        // this actually is not relevant, just adding anything
        // so that bar form is not empty
    }
}

Result of var_dump()

If our collection holds 3 Bar objects then the result will be:

array (size=1)
  'this_is_prototype' => boolean true

array (size=1)
  0 => boolean false

array (size=1)
  1 => boolean false

array (size=1)
  2 => boolean false

Conclusion

In buildForm $builder->getParent() will return parent builder only for prototype.

Issue / question

I need to access parent form to get some parameters. Why is parent dropped for existing collection elements? Is there any workaround?

Related github issue

Answer 1

bschussek:

The answer is that at the point when buildForm() is called, the parent
is not yet known (remember we are just building the form). So a form
should not depend on its parent. Instead, you should add options to
your type and set these options from the parent to modify the behavior
of the child.