**type**: ``mixed`` **default**: ``null``

Allows you to specify data for the prototype. Each new row added will initially

contain the data set by this option.

Allows you to define a specific data for the prototype. Each new row added will

initially contain the data set by this option.

By default, the same data as defined with ``entry_options`` for other entries

will be used.

..code-block::php

use Symfony\Component\Form\Extension\Core\Type\CollectionType;

use Symfony\Component\Form\Extension\Core\Type\TextType;

$builder->add('tags', CollectionType::class, array(

'class' =>\AppBundle\Entity\Tag::class,

'entry_type' => TextType::class,

'allow_add' => true,

'prototype' => true,

'prototype_data' => 'New Tag Placeholder',

));

prototype_name