feature #47075 [Mime] Change the way we avoid rendering an email twic…

…e (fabpot)

This PR was merged into the 6.2 branch.

Discussion
----------

[Mime] Change the way we avoid rendering an email twice

| Q             | A
| ------------- | ---
| Branch?       | 6.2
| Bug fix?      | yes-ish
| New feature?  | yes-ish <!-- please update src/**/CHANGELOG.md files -->
| Deprecations? | no <!-- please update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tickets       | n/a <!-- prefix each issue number with "Fix #", no need to create an issue if none exist, explain below instead -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#17065

Trying to kill several birds with one stone here.

I was not very happy with the way we ensured that emails were not renderer more than once.
This solution seems easier and allows for people to render an email **before** sending it to Messenger (important when you have Doctrine entities in the context for instance) as documented in the related doc PR.

Commits
-------

cc3b871 [Mime] Change the way we avoid rendering an email twice

src/Symfony/Bridge/Twig/Mime/BodyRenderer.php

@@ -45,15 +45,13 @@ public function render(Message $message): void
             return;
         }
 
-        $messageContext = $message->getContext();
-
-        $previousRenderingKey = $messageContext[__CLASS__] ?? null;
-        unset($messageContext[__CLASS__]);
-        $currentRenderingKey = $this->getFingerPrint($message);
-        if ($previousRenderingKey === $currentRenderingKey) {
+        if (null === $message->getTextTemplate() && null === $message->getHtmlTemplate()) {
+            // email has already been rendered
             return;
         }
 
+        $messageContext = $message->getContext();
+
         if (isset($messageContext['email'])) {
             throw new InvalidArgumentException(sprintf('A "%s" context cannot have an "email" entry as this is a reserved variable.', get_debug_type($message)));
         }
@@ -64,34 +62,20 @@ public function render(Message $message): void
 
         if ($template = $message->getTextTemplate()) {
             $message->text($this->twig->render($template, $vars));
+            $message->textTemplate(null);
         }
 
         if ($template = $message->getHtmlTemplate()) {
             $message->html($this->twig->render($template, $vars));
+            $message->htmlTemplate(null);
         }
 
+        $message->context([]);
+
         // if text body is empty, compute one from the HTML body
         if (!$message->getTextBody() && null !== $html = $message->getHtmlBody()) {
             $message->text($this->convertHtmlToText(\is_resource($html) ? stream_get_contents($html) : $html));
         }
-        $message->context($message->getContext() + [__CLASS__ => $currentRenderingKey]);
-    }
-
-    private function getFingerPrint(TemplatedEmail $message): string
-    {
-        $messageContext = $message->getContext();
-        unset($messageContext[__CLASS__]);
-
-        $payload = [$messageContext, $message->getTextTemplate(), $message->getHtmlTemplate()];
-        try {
-            $serialized = serialize($payload);
-        } catch (\Exception) {
-            // Serialization of 'Closure' is not allowed
-            // Happens when context contain a closure, in that case, we assume that context always change.
-            $serialized = random_bytes(8);
-        }
-
-        return md5($serialized);
     }
 
     private function convertHtmlToText(string $html): string