php - Symfony/Twig: how to pass additional data to a form? -

i'm looking way manage form data within myformtype.php. far i've label , placeholder, i'd store additional string, e.g. "more details".

appbundle\form\type\myformtype.php

// ... $builder->add('fieldname', texttype::class, [     'label' => 'my label',     'attr'  => ['placeholder' => 'my placeholder'],            'additionaldata' => ['info' => 'more information] // <- ???       ]); // ... 

myform.html.twig

label: {{form_label(form.fieldname)}}  textfield: {{form_widget(form.fieldname)}}   info: {{form_additionaldata(form.fieldname, 'info')}}  {# ??? #} 

i thinking passing data via data-*-attribute like:

// ... 'attr' => ['data-info' => 'more information'] // ... 

but how read data in way, without buggy workarounds?

any best/good practise issue?

thanks in advance!

by using form type extension way if it's common use case in application:

# src/appbundle/form/extension/formtypeextension.php  class formtypeextension extends abstracttypeextension {     public function buildview(formview $view, forminterface $form, array $options)     {         foreach ($options['extra_data'] $name => $data) {             $dataname = sprintf('data-%s', $name);             $view->vars['attr'][$dataname] = json_encode($data);         }     }      public function configureoptions(optionsresolver $resolver)     {         $resolver->setdefaults(array('extra_data' => array()));         $resolver->setallowedtypes('extra_data', 'array');     }      public function getextendedtype()     {         return formtype::class;     } } 

register form type extension:

# app/config/services.yml  services:     app.form.extension.form_type:         class: appbundle\form\extension\formtypeextension         tags:             - { name: form.type_extension, extended_type: symfony\component\form\extension\core\type\formtype } 

if:

$form->add('name', texttype::class, array(     'extra_data' => array(         'foo' => 'bar',          'baz' => array('name' => 'john'),     ), )); 

then:

<input type="text" id="form_name" name="form[name]" data-foo=""bar"" data-baz="{"name": "john"}"/> 

but how read data in way, without buggy workarounds?

in javascript context using jquery example:

var data = $('#form_name').data();  // data values converted json automatically alert(data.foo); // display: bar alert(data.baz.name); // display: john