Symfony 4 / Sonata: Create a Custom Form Field Type

We are going to see how we can create a custom field type.

In our example, we want a field that has the same rendering as a MoneyType field but in which we can add any suffix, as the money field only accepts currencies.

However, in our project we want to use kilograms, months or even kilometers. In short, a whole range of possible data types.

We start by creating our Type class:

// src/Form/Type/NumberSuffixType.php
namespace App\Form\Type;

use Symfony\Component\Form\AbstractType;
use Symfony\Component\Form\Extension\Core\Type\TextType;
use Symfony\Component\Form\Extension\Core\Type\IntegerType;
use Symfony\Component\Form\Extension\Core\Type\NumberType;
use Symfony\Component\OptionsResolver\Options;
use Symfony\Component\OptionsResolver\OptionsResolver;
use Symfony\Component\Form\FormViewInterface;
use Symfony\Component\Form\FormInterface;
use Symfony\Component\Form\FormTypeInterface;
use Symfony\Component\Form\FormView;

class NumberSuffixType extends AbstractType
    public function getParent()
        return NumberType::class;
        //return TextType::class;
    public function configureOptions(OptionsResolver $resolver)
            'suffix' => 'suffix',
            'field_options' => [],
    public function buildView(FormView $view, FormInterface $form, array $options)
        $view->vars['type'] = 'number';
        $view->vars['attr']['class'] = 'number_suffix';
    public function getBlockPrefix()
        return 'number_suffix';


Then we add our template

{# templates/Adminform/number_suffix_type.html.twig #}
{% block number_suffix_widget %}
    {% spaceless %}
       <div class="input-group">
                {{- block('form_widget_simple') -}}
                {% if suffix is not empty %}
                	<span class="input-group-addon"> {{ suffix }}</span>
                {% endif %}
    {% endspaceless %}
{% endblock %}

We have to register our template

# config/packages/twig.yaml
        - 'Admin/form/number_suffix_type.html.twig'

Additionally, we add a CSS rule to remove the arrows from the HTML5 numeric field.
To do this, we must reference a CSS file in the admin

            - css/admin.css

And we add our directive in our CSS file

input[class*="number_suffix"] {
    -moz-appearance: textfield;
input[class*="number_suffix"]:focus {
    -moz-appearance: number-input;

Then it's just a matter of using it like this:

            ->add('dureePossible1', NumberSuffixType::class, ['label'=>'Durée possible 1','suffix'=>'Mois','required'   => false])
            ->add('dureePossible2', NumberSuffixType::class, ['label'=>'Durée possible 2','suffix'=>'Mois','required'   => false])
            ->add('dureePossible3', NumberSuffixType::class, ['label'=>'Durée possible 3','suffix'=>'Mois','required'   => false])
            ->add('dureePossible4', NumberSuffixType::class, ['label'=>'Durée possible 4','suffix'=>'Mois','required'   => false])

Afterwards, it gives us a field like this