extends-form

name	extends-form
description	Expose a custom field in an existing Sylius admin form (Product, Taxon, Channel, …) via a Symfony FormTypeExtension, Twig hook and translation
argument-hint	[TargetModel] [FieldName]
allowed-tools	AskUserQuestion, Bash, Read, Edit, Write, Glob, Grep

Extend a Sylius admin form

Ask the user if not provided:

• TargetModel: the Sylius entity whose admin form receives the new field (e.g. Product, Taxon, Channel, Customer)
• FieldName: the property name, camelCase — must match the column on the entity (e.g. metadataTitle)
• FieldType: the Symfony form type to use — a scalar (TextType, TextareaType, IntegerType, CheckboxType) or a custom type such as {Related}AutocompleteType for a relation
• Whether the field is required (default: false)
• The target section hook (default: general). To list available sections, on Sylius 2.3+:

  bin/console sylius:debug:twig-hooks sylius_admin.{target_model_snake}
  

  On older versions, fall back to bin/console debug:config sylius_twig_hooks.

Prerequisites:

• The field must exist on the entity. Run /sylius-app:extends-model first for a Sylius core entity, or add the column on your own resource.
• For an entity-autocomplete field type, run /sylius-app:add-autocomplete first so {Related}AutocompleteType exists.

1. Identify the target FormType

bin/console sylius:debug:resource sylius.{target_model_snake}

The classes.form row in the output is the FormType FQCN used by the admin. Use it directly as the use statement and as the getExtendedTypes() return. Without an argument, the command lists every resource alias.

2. Create the FormTypeExtension

src/Form/Extension/{TargetModel}/{TargetModel}TypeExtension.php:

<?php

declare(strict_types=1);

namespace App\Form\Extension\{TargetModel};

use {TargetFormFqcn};  // value returned by step 1
use Symfony\Component\Form\AbstractTypeExtension;
use Symfony\Component\Form\Extension\Core\Type\{FieldType};  // or your custom type
use Symfony\Component\Form\FormBuilderInterface;

final class {TargetModel}TypeExtension extends AbstractTypeExtension
{
    public function buildForm(FormBuilderInterface $builder, array $options): void
    {
        $builder->add('{field_name}', {FieldType}::class, [
            'label' => 'app.form.{target_model_snake}.{field_name}',
            'required' => {required},
        ]);
    }

    public static {
         [{TargetModel}::];
    }
}

3. Register the service

Add to config/services.yaml:

services:
    app.form.extension.{target_model_snake}_type:
        class: App\Form\Extension\{TargetModel}\{TargetModel}TypeExtension
        tags:
            - { name: form.type_extension }

4. Create the Twig template

templates/admin/{target_model_snake}/form/sections/{section}/{field_name}.html.twig:

{{ form_row(hookable_metadata.context.form.{field_name}) }}

5. Register the Twig hooks (split by action)

One file per action under config/packages/twig_hooks/{target_model_snake}/. Loaded via the imports: block at the top of config/packages/_sylius.yaml (add - { resource: "twig_hooks/**/*.yaml" } if not already there).

If files already exist for this target (from a previous extends-form run), add the new entry under the existing hook key — do not overwrite.

config/packages/twig_hooks/{target_model_snake}/create.yaml:

sylius_twig_hooks:
    hooks:
        'sylius_admin.{target_model_snake}.create.content.form.sections.{section}':
            {field_name}:
                template: 'admin/{target_model_snake}/form/sections/{section}/{field_name}.html.twig'
                priority: -100

config/packages/twig_hooks/{target_model_snake}/update.yaml — same content, replace .create. with .update..

A negative priority places the field at the bottom of the section without renumbering existing entries.

6. Add the translation

Get the project's default locale:

bin/console debug:container --parameter=kernel.default_locale

Add to translations/messages.{locale}.yaml:

app:
    form:
        {target_model_snake}:
            {field_name}: '{Field label}'

7. Clear cache

bin/console cache:clear

8. Verify

• bin/console debug:form '{TargetFormFqcn}' (FQCN from step 1) lists {field_name} among the type's fields
• bin/console debug:translation {locale} --domain=messages 2>&1 | grep 'app.form.{target_model_snake}.{field_name}' finds the label.

---

Next steps

• Extending a Sylius core entity with a column → /sylius-app:extends-model (typical paired workflow: extend the entity, then expose the field here)
• Using an autocomplete type as the field → /sylius-app:add-autocomplete
• Displaying the new field in the admin grid → /sylius-app:extends-grid