[TASK] Update form ViewHelper page

Documentation/Global/Form/Index.rst

@@ -9,38 +9,92 @@ Form ViewHelper `<f:form>`
 
 ..  typo3:viewhelper:: form
     :source: /Global.json
-    :display: tags,description,gitHubLink,arguments
+    :display: tags,description,gitHubLink
+    :noindex:
+
+..  include:: /_Includes/_ExtbaseFormViewHelpers.rst.txt
+
+..  contents:: Table of contents
 
 ..  _typo3-fluid-form-example:
 
-Examples
-========
+Array parameter passed to Extbase controller action
+===================================================
+
+For example a very simplified search form could look like this:
+
+..  literalinclude:: _codesnippets/_PlainParameterForm.html
+    :caption: packages/my_extension/Resources/Private/Templates/Search/SearchForm.html
+
+The `Extbase controller <https://docs.typo3.org/permalink/t3coreapi:extbase-controller>`_
+action could for example look like this:
+
+..  literalinclude:: _codesnippets/_SearchController.php
+    :caption: packages/my_extension/Classes/Controller/SearchController.php
+
+..  _typo3-fluid-form-example-property:
+
+Property mapping - using the form with a model
+==============================================
+
+In most cases you will use the f:form ViewHelper with
+`Extbase models <https://docs.typo3.org/permalink/t3coreapi:extbase-model>`_ or
+data objects.
+
+For example, user could add a comment in such a form:
 
-A complex form with a specified encoding type
----------------------------------------------
+..  literalinclude:: _codesnippets/_CommentForm.html
+    :caption: packages/my_extension/Resources/Private/Templates/Comment/_CommentForm.html
 
-Form with enctype set::
+The Extbase Controller action displaying the form then creates the Domain object
+and passes it to the view. In the Fluid template above we use argument
+:ref:`object <t3viewhelper:viewhelper-argument-typo3-cms-fluid-viewhelpers-formviewhelper-object>`
+to pass any data the object might already contain to the ViewHelper.
 
-   <f:form action=".." controller="..." package="..." enctype="multipart/form-data">...</f:form>
+By using the argument "property" on the form input elements the properties of
+the model are automatically bound to the input elements.
 
-A Form which should render a domain object
-------------------------------------------
+The controller could look like this:
 
-Binding a domain object to a form::
+..  literalinclude:: _codesnippets/_CommentController.php
+    :caption: packages/my_extension/Classes/Controller/CommentController.php
 
-   <f:form action="..." name="customer" object="{customer}">
-      <f:form.hidden property="id" />
-      <f:form.textarea property="name" />
-   </f:form>
+If the model is not valid (see `Validation <https://docs.typo3.org/permalink/t3coreapi:extbase-validation>`_)
+Extbase will automatically refer the request back to the referring action
+(here commentFormAction()). By passing the object with the non-validated object
+to the view again, the user can see their faulty inputs and correct them instead
+of seeing an empty form.
 
-This automatically inserts the value of ``{customer.name}`` inside the
-textarea and adjusts the name of the textarea accordingly.
+..  _typo3-fluid-form-security:
+
+Security in Fluid forms
+=======================
+
+Fluid automatically adds a hidden field to forms, including an `__hmac`
+value. This value lists all allowed fields. If fields are added or
+removed via attacks, Extbase detects the mismatch and blocks submission.
+
+Form fields can be grouped in an array for efficient processing. The
+receiving action maps the data to a model, where validation occurs if
+rules are defined. Only valid data is passed to the action and stored in
+the database.
+
+..  _typo3-fluid-form-arguments:
+
+Arguments of the form ViewHelper
+================================
+
+..  include:: /_Includes/_ArbitraryArguments.rst.txt
+
+..  typo3:viewhelper:: form
+    :source: /Global.json
+    :display: arguments-only
 
 
 ..  _typo3-fluid-form-viewhelpers:
 
-ViewHelpers to be used within the form ViewHelper
-=================================================
+ViewHelpers for form input elements
+===================================
 
 ..  toctree::
     :titlesonly:

Documentation/Global/Form/_codesnippets/Comment.php

@@ -0,0 +1,19 @@
+<?php
+
+declare(strict_types=1);
+
+namespace MyVendor\MyExtension\Domain\Model;
+
+use TYPO3\CMS\Extbase\Annotation\Validate;
+use TYPO3\CMS\Extbase\DomainObject\AbstractEntity;
+
+class Comment extends AbstractEntity
+{
+    #[Validate(['validator' => 'EmailAddress'])]
+    protected string $email = '';
+
+    #[Validate(['validator' => 'StringLength', 'options' => ['maximum' => 500]])]
+    protected string $content = '';
+
+    // Getters and setters ...
+}

Documentation/Global/Form/_codesnippets/_CommentController.php

@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace MyVendor\MyExtension\Controller;
+
+use Psr\Http\Message\ResponseInterface;
+use T3docs\BlogExample\Domain\Model\Comment;
+use T3docs\BlogExample\Domain\Repository\CommentRepository;
+use TYPO3\CMS\Extbase\Annotation\IgnoreValidation;
+use TYPO3\CMS\Extbase\Mvc\Controller\ActionController;
+
+class CommentController extends ActionController
+{
+    public function __construct(
+        protected readonly CommentRepository $commentRepository,
+    ) {}
+
+    #[IgnoreValidation(['argumentName' => 'newComment'])]
+    public function commentFormAction(?Comment $newComment = null): ResponseInterface
+    {
+        if ($newComment === null) {
+            $newComment = new Comment();
+            $newComment->setDate(new \DateTime());
+        }
+        // The assigned object will be used in argument object
+        $this->view->assign('newComment', $newComment);
+        return $this->htmlResponse();
+    }
+
+    public function createAction(
+        // This parameter must have the same name as argument `objectName` of f:form
+        Comment $comment,
+    ): ResponseInterface {
+        $this->commentRepository->add($comment);
+        $this->addFlashMessage('Comment was saved');
+        return $this->redirect('show');
+    }
+}

Documentation/Global/Form/_codesnippets/_CommentForm.html

@@ -0,0 +1,16 @@
+<html xmlns:f="http://typo3.org/ns/TYPO3/CMS/Fluid/ViewHelpers"
+      data-namespace-typo3-fluid="true">
+    <f:form action="create" controller="Comment" objectName="comment" object="{newComment}" method="post">
+        <div>
+                <label for="tx-blogexample-email">E-Mail::</label>
+                <f:form.textfield property="email" type="email" id="tx-blogexample-email"/>
+        </div>
+        <div>
+                <label for="tx-blogexample-content">Message:</label>
+                <f:form.textarea property="content" id="tx-blogexample-content" rows="8" cols="46"/>
+        </div>
+        <div>
+                <f:form.submit class="button" value="Submit"/>
+        </div>
+    </f:form>
+</html>

Documentation/Global/Form/_codesnippets/_PlainParameterForm.html

@@ -0,0 +1,9 @@
+<f:form action="search" method="post" pageUid="{settings.targetPid}">
+    <div>
+        <label for="sword">Search:</label>
+        <f:form.textfield name="search[sword]" value="{sword}" id="sword" />
+    </div>
+    <div>
+        <f:form.submit name="search[submitButton]" value="Submit" />
+    </div>
+</f:form>

Documentation/Global/Form/_codesnippets/_SearchController.php

@@ -0,0 +1,17 @@
+<?php
+
+declare(strict_types=1);
+
+namespace MyVendor\MyExtension\Controller;
+
+use Psr\Http\Message\ResponseInterface;
+use TYPO3\CMS\Extbase\Mvc\Controller\ActionController;
+
+class SearchController extends ActionController
+{
+    public function searchAction(array $search = []): ResponseInterface
+    {
+        // TODO: implement search
+        return $this->htmlResponse();
+    }
+}

Documentation/_Includes/_ArbitraryArguments.rst.txt

@@ -0,0 +1,4 @@
+..  admonition:: Allows arbitrary arguments
+
+    This ViewHelper allows you to pass arbitrary arguments not defined below
+    directly to the HTML tag created. This includes custom `data-` arguments.

Documentation/_Includes/_ExtbaseFormViewHelpers.rst.txt

@@ -0,0 +1,7 @@
+..  attention::
+    ..  versionchanged:: 12.0
+        The f:form ViewHelpers can only be used within the Extbase context.
+
+        In a non-Extbase context, for example within a
+        `FLUIDTEMPLATE <https://docs.typo3.org/permalink/t3tsref:cobj-template>`_
+        Use plain HTML `<form>` and `<input>` tags.