Listing 43.1. Klasa My/FrontendBundle/Admin/CityAdmin.php
<?php

namespace My\FrontendBundle\Admin;

use Sonata\AdminBundle\Admin\Admin;
use Sonata\AdminBundle\Datagrid\ListMapper;
use Sonata\AdminBundle\Datagrid\DatagridMapper;
use Sonata\AdminBundle\Validator\ErrorElement;
use Sonata\AdminBundle\Form\FormMapper;

class CityAdmin extends Admin
{
    protected function configureFormFields(FormMapper $formMapper)
    {
        $formMapper
            ->add('name')
            ->add('population', 'number')
        ;
    }

    protected function configureDatagridFilters(DatagridMapper $datagridMapper)
    {
        $datagridMapper
            ->add('name')
        ;
    }

    protected function configureListFields(ListMapper $listMapper)
    {
        $listMapper
            ->addIdentifier('name')
            ->add('population', 'number')
        ;
    }

}