How to display the current picture above the uploa

Question

I am using SonataAdminBundle (with Doctrine2 ORM) and I have successfully added a file upload feature to my Picture model.

I would like, on the Show and Edit pages, to display a simple <img src="{{ picture.url }} alt="{{ picture.title }} /> tag just above the relevant form field (provided that the Picture being edited is not new, of course), so that the user may see the current photo, and decide whether to change it or not.

After hours of research, I've been unable to figure out how to do it. I suppose I need to override some template, but I'm a bit lost... Can somebody give me a hint?

Thank you!

Here is the relevant section of my PictureAdmin class.

protected function configureFormFields(FormMapper $formMapper)
{
    $formMapper
        ->add('category', NULL, ['label' => 'Catégorie'])
        ->add('title', NULL, ['label' => 'Titre'])
        ->add('file', 'file', ['required' => false, 'label' => 'Fichier']) // Add picture near this field
        ->add('creation_date', NULL, ['label' => 'Date d\'ajout'])
        ->add('visible', NULL, ['required' => false, 'label' => 'Visible'])
        ->add('position', NULL, ['label' => 'Position']);
}

protected function configureShowFields(ShowMapper $showMapper)
{
    $showMapper
        ->add('id', NULL, ['label' => 'ID'])
        ->add('category', NULL, ['label' => 'Catégorie'])
        ->add('title', NULL, ['label' => 'Titre'])
        ->add('slug', NULL, ['label' => 'Titre (URL)'])
        ->add('creation_date', NULL, ['label' => 'Date d\'ajout'])
        ->add('visible', NULL, ['label' => 'Visible'])
        ->add('position', NULL, ['label' => 'Position']);
        // Add picture somewhere
}

Answer 1

you can easily do this on edit page by helpers(FormMapper->setHelps) or option "help" pass on FormMapper

protected function configureFormFields(FormMapper $formMapper) {
    $options = array('required' => false);
    if (($subject = $this->getSubject()) && $subject->getPhoto()) {
        $path = $subject->getPhotoWebPath();
        $options['help'] = '<img src="' . $path . '" />';
    }

    $formMapper
        ->add('title')
        ->add('description')
        ->add('createdAt', null, array('data' => new \DateTime()))
        ->add('photoFile', 'file', $options)
    ;
}