82_DynamicChoice.md

Dynamic Choice

The Dynamic Choice Type allows to generate Drop-Down / Checkbox / Radio Elements with dynamic content. For Example a Product List.

Usage

In the FormBuilder Backend add a "Dynamic Choice Type" Field. There you'll find a "Service Name" Field with the defined Services. In the next Section you'll learn how to add such services.

Error Handling

Important: It's not possible to add custom validation messages within the DynamicChoice Service. That's because you're dealing with a already rendered form type (dynamic choice). To add some validations you could use the default constraints in the form builder itself or by extending the default options via form extensions.

Add Service

App\Services\FormBuilderBundle\ProductChoices:
    autowire: true
    public: false
    tags:
        - { name: form_builder.dynamic_choice_builder, label: 'Product Selector' }

PHP Service (Simple)

<?php

namespace App\Services\FormBuilderBundle;

use FormBuilderBundle\Form\ChoiceBuilderInterface;
use Symfony\Component\Form\CallbackTransformer;
use Symfony\Component\Form\FormBuilderInterface;
use App\Model\Product;

class ProductChoices implements ChoiceBuilderInterface
{
    protected $builder;

    public function setFormBuilder(FormBuilderInterface $builder)
    {
        $this->builder = $builder;

        // transform data back to string (to display the product name in the email for example)
        $builder->addModelTransformer(new CallbackTransformer(
            function ($entries) {
                return $entries;
            },
            function ($entries) {
                if (empty($entries)) {
                    return $entries;
                }

                if (is_array($entries)) {
                    $data = [];
                    foreach ($entries as $id) {
                        $product = Product::getById($id);
                        $data[] = $product->getName();
                    }
                    return implode(', ', $data);
                } else {
                    $product = Product::getById($entries);
                    return $product->getName();
                }
            }
        ));
    }

    public function getList()
    {
        $product1 = Product::getById(89);
        $product2 = Product::getById(47);

        return [
            $product1->getName() => $product1->getId(),
            $product2->getName() => $product2->getId()
        ];
    }
}

PHP Service (Advanced)

You could implement the AdvancedChoiceBuilderInterface to get more control about your choice element:

<?php

namespace App\Services\FormBuilderBundle;

use FormBuilderBundle\Form\AdvancedChoiceBuilderInterface;
use Symfony\Component\Form\FormBuilderInterface;
use App\Model\Product;

class ProductChoices implements AdvancedChoiceBuilderInterface
{
    protected $builder;

    public function setFormBuilder(FormBuilderInterface $builder)
    {
        // same as in simple service
    }

    public function getList()
    {
        // same as in simple service
    }

    public function getChoiceValue($element = null)
    {
        // @see: https://symfony.com/doc/current/reference/forms/types/choice.html#choice-value
    }

    public function getChoiceLabel($element, $key, $index)
    {
        // @see: https://symfony.com/doc/current/reference/forms/types/choice.html#choice-label
    }

    public function getChoiceAttributes($element, $key, $index)
    {
        // @see: https://symfony.com/doc/current/reference/forms/types/choice.html#choice-attr
    }

    public function getGroupBy($element, $key, $index)
    {
        // @see: https://symfony.com/doc/current/reference/forms/types/choice.html#group-by
    }

    public function getPreferredChoices($element, $key, $index)
    {
        // @see: https://symfony.com/doc/current/reference/forms/types/choice.html#preferred-choices
    }
}