70_Events.md

Events

It's possible to add some custom fields to every form.

1. Register a Listener:

services:
    app.event_listener.form_builder.listener:
        class: AppBundle\EventListener\FormListener
        tags:
            - { name: kernel.event_subscriber }

2. To add custom fields, you need to listen to the form pre set data event.

Important! Do not add fields to the symfony form directly! Form Builder will add additional data to your field, like template, order, email label and so on.

<?php

namespace AppBundle\EventListener;

use FormBuilderBundle\Event\Form\PreSetDataEvent;
use FormBuilderBundle\FormBuilderEvents;
use FormBuilderBundle\Storage\FormInterface as FormBuilderFormInterface;
use Symfony\Component\Form\FormInterface;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;
use Symfony\Component\Form\Extension\Core\Type\EmailType;
use Symfony\Component\Validator\Constraints\NotBlank;

class FormListener implements EventSubscriberInterface
{
    public static function getSubscribedEvents()
        {
            return [
                FormBuilderEvents::FORM_PRE_SET_DATA => 'formPreSetData'
            ];
        }
        
    public function formPreSetData(PreSetDataEvent $event)
    {
        $formEvent = $event->getFormEvent();

        /** @var FormBuilderFormInterface $dataClass */
        $dataClass = $formEvent->getData();

        // get the form id/name from backend
        $formId = $dataClass->getId();
        $formName = $dataClass->getName();

        // get form options like the selected form preset
        $formOptions = $event->getFormOptions();

        //add dynamic fields depending on custom presets, is available.
        var_dump($formOptions['formPreset']);

        // add your fields
        $dataClass->addDynamicField(
            
            //field name
            'your_dynamic_field_name',
            
            //field type
            EmailType::class,
            
            //all the field options
            [
                //no need to add translations here, fb will do this for you.
                'label'       => 'Your Field Label',
                'constraints' => [
                    new NotBlank(),
                ]
            ],
            
            //optional options
            [
                //add a template
                'template' => 'col-xs-6',
                
                //set the order of your field
                'order' => 10,
                
                //no need to add translations here, fb will do this for you.
                'email_label' => 'Your Field Email Label',

                // form builder usually tries to render the value for the email by itself.
                
                // 1. if you need to transform the value: use a closure
                //'email_value_transformer' => function(FormInterface $field, $value, $locale) {
                //    return 'YOUR_TRANSFORMED_VALUE'
                //},

                // 2. or a class method
                //'email_value_transformer' => [$this, 'checkValue']
            ]
        );
    }

    public function checkValue(FormInterface $field, $value, $locale)
    {
        return 'YOUR_TRANSFORMED_VALUE';
    }
}