[FrameworkBundle] Add AbstractController::renderBlock() and renderBlockView()

[nicolas-grekas]

Q	A
Branch?	6.4
Bug fix?	no
New feature?	yes
Deprecations?	no
Tickets	-
License	MIT
Doc PR	-

This would be especially useful when generating turbo-stream responses.
Right now, the doc recommends creating new partial templates, but this increases the complexity and scatters HTML fragments. Instead, we could encourage using twig blocks.

Adding this could help remove some boilerplate.

before (using blocks):

return new Response($this->container->get('twig')->load('foo.html.twig')->renderBlock('the_block', $context));

after:

return $this->renderBlock('foo.html.twig', 'the_block', $context);

[stof]

I think it might be more readable with a separate renderBlock method instead of an optional argument, allowing to easily distinguish whether we only render a block of the template and not the full block (especially when the list of variables become long and is defined inline rather than using a $context variable).

[nicolas-grekas]

In order to prevent code duplication, we could add renderBlock but keep the new argument on renderView. Otherwise we'll need a new renderBlockView and it should duplicate most of the code in renderView/render. I'm not keen on adding renderBlockView.

[nicolas-grekas]

Mmm, even adding renderBlock requires duplicating from render.

Another idea might be to use the parameters array to add options, for example ['@block' => 'the_block'].
Can we reference a variable named @block from inside a twig template? If not, then this convention is safe from collisions.
But it's more difficult to discover.

With all this in mind, I think I prefer the additional argument.

[yceruto]

I prefer the separate methods approach too, as it is more aligned with SRP and also results in a better argument order.

return $this->renderBlock('foo.html.twig', 'the_block', $context);

An alternative could be moving the duplicated code to new private methods

private function normalizeViewParameters(array $parameters): array
{
    foreach ($parameters as $k => $v) {
        if ($v instanceof FormInterface) {
            $parameters[$k] = $v->createView();
        }
    }

    return $parameters;
}

private function prepareResponse(Response $response, array $parameters, string $content): Response
{
    if (200 === $response->getStatusCode()) {
        foreach ($parameters as $v) {
            if ($v instanceof FormInterface && $v->isSubmitted() && !$v->isValid()) {
                $response->setStatusCode(422);
                break;
            }
        }
    }

    $response->setContent($content);

    return $response;
}

[nicolas-grekas]

OK, thanks for the feedback :)

PR updated to add method AbstractController::renderBlock() and argument $block to renderView()

[yceruto]

by the way, I would do the same for renderBlockView(), and use normalizeViewParameters() (defined in my previous comment) to avoid duplication. The LogicException is not included as it's a different method, so the message changes.

[yceruto]

Full suggestion https://gist.github.com/yceruto/fc5594963df6a642c34111eea1a82b17

[nicolas-grekas]

I'm not sold on renderViewBlock. There I still like the additional argument for renderView...

[nicolas-grekas]

Friendly ping @symfony/mergers

[dunglas]

Cool!

[lyrixx]

I like it !