How Do I Use __toString() with a form in Symfony 2?

Question

I get this error:

Entities passed to the choice field must have a "__toString()" method defined (or you can also override the "property" option).

This isn't confusing me, as the fields that I try to render when I get this error are either INT's or BIGINT's. What is confusing me is where I'm supposed to use __toString() in relation to the field?

Also, what is this "property" option the error message says I can override?

Cheers

EDIT:

Here's the code that renders the form:

public function buildForm(FormBuilder $builder, array $options)
    {
        $builder->add('id');
        $builder->add('title');
        $builder->add('slug');
        $builder->add('content');
        $builder->add('keywords');
        $builder->add('contenttype');
        $builder->add('hits');
        $builder->add('mainpage');
        $builder->add('hasmainpage');
        $builder->add('ismainpage');
    }

Here's the code in my Controller class that handles this:

    $pageadd = new Content();
    $form = $this->createForm(new PageAdd(), $pageadd);

    $request = $this->getRequest();
    if ($request->getMethod() == 'GET') {
        $form->bindRequest($request);

        if ($form->isValid()) {

            $em = $this->getDoctrine()
                       ->getEntityManager();
            $em->persist($pageadd);
            $em->flush();

            return $this->redirect($this->generateUrl('ShoutAdminBundle_add'));
        }
    }

    return $this->render('ShoutAdminBundle:Default:pageadd.html.twig', array(
        'form' => $form->createView()
    ));

And here is the code that's in my Twig file:

        <form action="{{ path('ShoutAdminBundle_adminpageadd') }}" method="post" {{ form_enctype(form) }} class="blogger">
            {{ form_errors(form) }}

            <p class="row">
                {{ form_label(form.id, 'ID*', { 'attr': {'class': 'title'} }) }}
                {{ form_errors(form.id) }}
                {{ form_widget(form.id, { 'attr': {'class': 'textfield'}}) }}
            </p>
            <p class="row">
                {{ form_label(form.title, 'Title*', { 'attr': {'class': 'title'} }) }}
                {{ form_errors(form.title) }}
                {{ form_widget(form.title, { 'attr': {'class': 'textfield'}}) }}
            </p>
            <p class="row">
                {{ form_label(form.slug, 'Slug*', { 'attr': {'class': 'title'} }) }}
                {{ form_errors(form.slug) }}
                {{ form_widget(form.slug, { 'attr': {'class': 'textfield'}}) }}
            </p>
            <p class="row">
                {{ form_label(form.content, 'Content*', { 'attr': {'class': 'title'} }) }}
                {{ form_errors(form.content) }}
                {{ form_widget(form.content, { 'attr': {'class': 'textfield'}}) }}
            </p>
            <p class="row">
                {{ form_label(form.keywords, 'Keywords*', { 'attr': {'class': 'title'} }) }}
                {{ form_errors(form.keywords) }}
                {{ form_widget(form.keywords, { 'attr': {'class': 'textfield'}}) }}
            </p>
            <p class="row">
                {{ form_label(form.contenttype, 'Content Type*', { 'attr': {'class': 'title'} }) }}
                {{ form_errors(form.contenttype) }}
                {{ form_widget(form.contenttype, { 'attr': {'class': 'textfield'}}) }}
            </p>
            <p class="row">
                {{ form_label(form.hits, 'Hits*', { 'attr': {'class': 'title'} }) }}
                {{ form_errors(form.hits) }}
                {{ form_widget(form.hits, { 'attr': {'class': 'textfield'}}) }}
            </p>
            <p class="row">
                {{ form_label(form.mainpage, 'Main Page*', { 'attr': {'class': 'title'} }) }}
                {{ form_errors(form.mainpage) }}
                {{ form_widget(form.mainpage, { 'attr': {'class': 'textfield'}}) }}
            </p>
            <p class="row">
                {{ form_label(form.hasmainpage, 'Has Main Page*', { 'attr': {'class': 'title'} }) }}
                {{ form_errors(form.hasmainpage) }}
                {{ form_widget(form.hasmainpage, { 'attr': {'class': 'textfield'}}) }}
            </p>
            <p class="row">
                {{ form_label(form.ismainpage, 'Is Main Page*', { 'attr': {'class': 'title'} }) }}
                {{ form_errors(form.ismainpage) }}
                {{ form_widget(form.ismainpage, { 'attr': {'class': 'textfield'}}) }}
            </p>

            {{ form_rest(form) }}
            <p class="row">
                <input type="submit" value="Save This Page" class="savebutton" />
            </p>
        </form>

Answer 1

I worked it out, with thanks to this blog post.

I took your advice firstly greg0ire, but I still received the error. What I did however was I added:

$builder->add('hasmainpage','entity', array('class'=>'Shout\AdminBundle\Entity\Admin', 'property'=>'id', ));

What I realised (I didn't know at the time of writing the original question) was that the error occurred because the field had a relationship attached to it, and when it tried to render the field it couldn't because of the relationship.

It's now fixed thankfully!