minor #19328 Fix code example: replace request get() with all() method to support non-scalar types (alejgarciarodriguez)

This PR was merged into the 5.4 branch.

Discussion
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Fix code example: replace request get() with all() method to support non-scalar types

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Method `$request->request->get` does not support non-scalar types so it won't work with forms since they are received as an array type.

Using `get` used to work in older Symfony versions but no longer does, now an exception is thrown.

IMO we should use `all` method instead in this example.

Commits
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3a0df2b replace get() with all() method to support non-scalar types

Author: xabbuh

form/direct_submit.rst

@@ -17,7 +17,7 @@ control over when exactly your form is submitted and what data is passed to it::
         $form = $this->createForm(TaskType::class, $task);
 
         if ($request->isMethod('POST')) {
-            $form->submit($request->request->get($form->getName()));
+            $form->submit($request->request->all($form->getName()));
 
             if ($form->isSubmitted() && $form->isValid()) {
                 // perform some action...