Symfony Tips : Find form theme override block name

06 February 2015

I don’t know if you are like me but I have a very hard time remembering how symfony and twig build the block name used in form theming. I often have to read again the documentation : How to customize form rendering. And it has not been enough for some specific use cases in my project.

So last time, I decided to track how Symfony build these names and find a way to display them in order to help me when theming my forms.

I think I found a pretty neat solution which could be useful for a lot of Symfony developer.

Just add a var_dump (temporary) in the loadResourceForBlockName method in the TwigRendererEngine class :

* Loads the cache with the resource for a given block name.
* This implementation eagerly loads all blocks of the themes assigned to the given view
* and all of its ancestors views. This is necessary, because Twig receives the
* list of blocks later. At that point, all blocks must already be loaded, for the
* case that the function "block()" is used in the Twig template.
* @see getResourceForBlock()
* @param string   $cacheKey  The cache key of the form view.
* @param FormView $view      The form view for finding the applying themes.
* @param string   $blockName The name of the block to load.
* @return bool True if the resource could be loaded, false otherwise.
protected function loadResourceForBlockName($cacheKey, FormView $view, $blockName)


The file should be located in vendor/symfony/symfony/src/Symfony/Bridge/Twig/Form/TwigRendererEngine.php.

This is what you should see :

Now you can use any of these block names in your form theme twig file to style your forms.