Symfony2: KnpPaginator only show the first page with POST form

Question

I'm using this bundle in an application. The controller is the typical that shows a search form, take the response and process it (an example):

public function indexAction()
{
    $request = $this->getRequest();

    $example = new Example();

    $form = $this->createForm(new ExampleFindType(), $example, array(
            'action' => $this->generateUrl('example_find'),
            'method' => 'POST',
    ));

    $form->handleRequest($request);

    if ($form->isValid())
    {
        $em = $this->getDoctrine()->getManager();

        $examples = $em->getRepository('ApplicationExampleBundle:Example')
            ->find_by_fields($example);

        $paginator  = $this->get('knp_paginator');              

        $pagination = $paginator->paginate(
                $examples,
                $this->get('request')->query->get('p', 1),
                20
        );

        return $this->render('ApplicationExampleBundle:Default:searchResults.html.twig',
                array('pagination' => $pagination));
    }

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

When I perform the search I see the results list and the paginator correctly. The problem appears when I press the link to the next page. The link id generated well, with the URL ending with "?p=2" but it seems that the form POST data is not resent because it sent me to the search form page ($form->isValid() is false).

If I change the form method from POST to GET and pass the parameters in the URL:

$form = $this->createForm(new ExampleFindType(), $example, array(
           'action' => $this->generateUrl('example_find'),
           'method' => 'GET',
));

the paginator works perfect.

Am I doing something wrong? Is possible to use a POST form?

I've searched an answer but all the KnpPagintor controller examples I've seen don't generate the query with forms, and this question hasn't helped me.

Thanks.

Answer 1

You shouldn't use POST method to get data.

Otherwise, if you need to use the POST method then you need the data in the session. However it's difficult to build a nice user experience while it just makes more sense to use a GET method.

You can find an extensive documentation about HTTP on MDN.

• A GET method should be used when you request data.
• A POST method should be used when you save data (like saving a comment into a database) or other data manipulation.

Google uses a GET on their own search page.

https://www.google.com/#q=symfony&start=10

q is what I searched for and start is the paginator value. They probably use an offset instead of a page number to avoid calculating the offset (faster and less expensive).