UPGRADE FROM 1.0

Create example project Bus (src/Bus)

In Sonata Admin Class:, _(*2)

// namespace Bus\MainBundle\Admin;

// Fields to be shown on create/edit forms
protected function configureFormFields(FormMapper $formMapper)
{
    $formMapper
        ->add('name')
        ->add('position', 'mapmarker', array('attr' =>
                array('draggable' => true,
                     'limit' => 1,
                     'center-lat' => 40.177037117759895,
                     'center-lng' => 44.51488494873047,
                     'zoom' => 12) ))
        ->add('position', 'mapmarker')
        ->add('creationDate')
        ;

}

or:, _(*3)

// namespace Bus\MainBundle\Admin;

// Fields to be shown on create/edit forms
protected function configureFormFields(FormMapper $formMapper)
{
    $formMapper
        ->add('name')
        ->add('position', 'mapmarker', array('attr' =>
                array('draggable' => true,
                     'limit' => 1,
                     'center-lat' => 40.177037117759895,
                     'center-lng' => 44.51488494873047,
                     'zoom' => 12) ))
        ->add('position', 'mapmarker')
        ->add('creationDate')
        ;

}

Add method in the same file, with which you can include map twig, _(*4)

public function getFormTheme() {
    return array('BusMapBundle:Admin:mapmarker_edit.html.twig');
}

Create new methods in Entity file, that will create and return an array with parameters longitude and latitude, _(*5)

/**
 * Get getPosition
 * @return array
 *
 */
public function getPosition()
{
    return array('position' => array('lat' => $this->latitude,'lng' => $this->longitude));
}
/**
 * Set setPosition
 * @param array $latlng
 * @return Stop
 *
 */
public function setPosition($latlng)
{
    $this
        ->setLatitude($latlng['lat'])
        ->setLongitude($latlng['lng']);
    return $this;
}

consider that there are already properties:, _(*6)

/**
 * @var float
 *
 * @ORM\Column(name="longitude", type="decimal", nullable=false, scale=7)
 */
private $longitude;

/**
 * @var float
 *
 * @ORM\Column(name="latitude", type="decimal", nullable=false, scale=7)
 */
private $latitude;

Create services in admin.xml, _(*7)

// EntityName - is your entity Class
<service id="sonata.admin.main.EntityName.route" class="Bus\MainBundle\Admin\EntityNameAdmin">
  <tag name="sonata.admin" manager_type="orm" group="Entity" label="EntityNameAdmin"/>
  <argument/>
    <argument>Bus\MainBundle\Entity\EntityName</argument>
    <argument/>
    <call method="setTemplate">
    <argument>edit</argument>
        <argument>BusMapBundle:Admin:edit.html.twig</argument>
    </call>
</service>