Add a variable to all rendering - symfony

Question

I'm operating on a symfony application and I would like to set a new variable from all controllers to all rendering.
The reason is that something in my footer has become dynamic and in compliance with the MVC pattern I'd like to put the processing of this new data in my controllers.
What is the good way to do this with symfony ?
EDIT
I am not using symfony as a REST API, the Symfony server is only serving twig rendered templates as HTML.
Details on my case :
the current twig template has hard-coded titles for a form :
<div>
<h2>Today</h2>
<!-- today's inputs .... -->
</div>
<div>
<h2>Tomorrow</h2>
<!-- tomorrow's inputs .... -->
</div>
I'd like to give to variables to my views : $today and $tomorrow.
This way I'd be able to render day names instead of today or tomorrow.
<div>
<h2>{{ today }}</h2>
<!-- today's inputs .... -->
</div>
<div>
<h2>{{ tomorrow }}</h2>
<!-- tomorrow's inputs .... -->
</div>
For example if today is Tuesday, variables has to be assigned this way :
$today = "Tuesday" and $tomorrow = "Wednesday".
What's more
This is not a question about this specific case. I'd like to now if there is a way to pass a variable to all views without editing all controllers. As I see it, I'd put a parent action to all controller to generate this variable. I just wanted to know if this is the usual way.
I don't want to use ajax calls, and I don't want to put complex twig code inside my template. I want to handle this via controllers.

Answer 1

Please read official documentation about using global variables.
Off the top of my head - you can inject...
...scalar values from the global twig config
...scalar values from the service container parameters
...services (read php objects)
Or you can write Twig extension, like:
class DateExtension extends \Twig_Extension
{
public function getFunctions()
{
return [
new \Twig_SimpleFunction('get_date', array($this, 'getDate'))
];
}
public function getDate($date)
{
// format it how you want
return (new \DateTime($date))->format('Y-m-d H:i:s');
}
}
And then use it in any template simply by:
<div>
<h2>{{ get_date('today') }}</h2>
<!-- today's inputs .... -->
</div>
<div>
<h2>{{ get_date('tomorrow') }}</h2>
<!-- tomorrow's inputs .... -->
</div>

Answer 2

About what kind of "dynamic" do you speak? If this dynamic goes from changing of some value stored in the data storage of your app, than, I belive, you could define controller action to retrive this data from, for example, your database and then call it via AJAX on every page load to obtain those value on client-side. Or maybe even use help of WebSocket's. But this is just assumption. If you really need help you should provide us more information about context of your task.