Refactor flash message handling to use translatable messages

Replaced raw translations with Symfony's TranslatableMessage for flash messages in the controller. Updated Twig templates to use the `|trans` filter for consistency in rendering translations. This ensures better handling of multilingual content across the application.

.changes/unreleased/DX-20250401-144728.yaml

@@ -0,0 +1,6 @@
+kind: DX
+body: Allow TranslatableMessage in flash messages
+time: 2025-04-01T14:47:28.814268801+02:00
+custom:
+    Issue: ""
+    SchemaChange: No schema change

docs/source/development/messages-to-users.rst

@@ -20,19 +20,26 @@ The four following levels are defined :
 +-----------+----------------------------------------------------------------------------------------------+
 |Key        |Intent                                                                                        |
 +===========+==============================================================================================+
-|alert      |A message not linked with the user action, but which should require an action or a            |
-|           |correction.                                                                                   |
-+-----------+----------------------------------------------------------------------------------------------+
 |success    |The user action succeeds.                                                                     |
 +-----------+----------------------------------------------------------------------------------------------+
 |notice     |A simple message to give information to the user. The message may be linked or not linked with|
 |           |the user action.                                                                              |
 +-----------+----------------------------------------------------------------------------------------------+
-|warning    |A message linked with an action, the user should correct.                                     |
-+-----------+----------------------------------------------------------------------------------------------+
 |error      |The user's action failed: he must correct something to process the action.                    |
 +-----------+----------------------------------------------------------------------------------------------+
 
+We can use :code:`TranslatableMessage` (and other :code:`TranslatableMessageInterface` instances) into the controller:
+
+.. code-block:: php
+
+   // in a controller action:
+   if (($session = $request->getSession()) instanceof Session) {
+       $session->getFlashBag()->add(
+           'success',
+           new TranslatableMessage('saved_export.Saved export is saved!')
+       );
+   }
+
 .. seealso::
 
    `Flash Messages on Symfony documentation <http://symfony.com/doc/current/book/controller.html#flash-messages>`_

src/Bundle/ChillMainBundle/Controller/SavedExportController.php

@@ -32,6 +32,7 @@ use Symfony\Component\HttpKernel\Exception\AccessDeniedHttpException;
 use Symfony\Component\Routing\Annotation\Route;
 use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
 use Symfony\Component\Security\Core\Security;
+use Symfony\Component\Translation\TranslatableMessage;
 use Symfony\Contracts\Translation\TranslatorInterface;
 
 final readonly class SavedExportController
@@ -64,7 +65,7 @@ final readonly class SavedExportController
 
             $session = $request->getSession();
             if ($session instanceof Session) {
-                $session->getFlashBag()->add('success', $this->translator->trans('saved_export.Export is deleted'));
+                $session->getFlashBag()->add('success', new TranslatableMessage('saved_export.Export is deleted'));
             }
 
             return new RedirectResponse(
@@ -111,7 +112,7 @@ final readonly class SavedExportController
             $this->entityManager->flush();
 
             if (($session = $request->getSession()) instanceof Session) {
-                $session->getFlashBag()->add('success', $this->translator->trans('saved_export.Saved export is saved!'));
+                $session->getFlashBag()->add('success', new TranslatableMessage('saved_export.Saved export is saved!'));
             }
 
             return new RedirectResponse(
@@ -144,7 +145,7 @@ final readonly class SavedExportController
             $this->entityManager->flush();
 
             if (($session = $request->getSession()) instanceof Session) {
-                $session->getFlashBag()->add('success', $this->translator->trans('saved_export.Saved export is saved!'));
+                $session->getFlashBag()->add('success', new TranslatableMessage('saved_export.Saved export is saved!'));
             }
 
             return new RedirectResponse(
@@ -157,8 +158,8 @@ final readonly class SavedExportController
                 '@ChillMain/SavedExport/edit.html.twig',
                 [
                     'form' => $form->createView(),
-                ]
+                ],
-            )
+            ),
         );
     }
 
@@ -194,8 +195,8 @@ final readonly class SavedExportController
                 [
                     'grouped_exports' => $exportsGrouped,
                     'total' => \count($exports),
-                ]
+                ],
-            )
+            ),
         );
     }
 }

src/Bundle/ChillMainBundle/Resources/views/layoutWithVerticalMenu.html.twig

@@ -10,19 +10,19 @@
 
                 {% for flashMessage in app.session.flashbag.get('success') %}
                     <div class="col-8 alert alert-success flash_message">
-                        <span>{{ flashMessage|raw }}</span>
+                        <span>{{ flashMessage|trans }}</span>
                     </div>
                 {% endfor %}
 
                 {% for flashMessage in app.session.flashbag.get('error') %}
                     <div class="col-8 alert alert-danger flash_message">
-                        <span>{{ flashMessage|raw }}</span>
+                        <span>{{ flashMessage|trans }}</span>
                     </div>
                 {% endfor %}
 
                 {% for flashMessage in app.session.flashbag.get('notice') %}
                     <div class="col-8 alert alert-warning flash_message">
-                        <span>{{ flashMessage|raw }}</span>
+                        <span>{{ flashMessage|trans }}</span>
                     </div>
                 {% endfor %}