View

The view’s responsibility is solely the visual presentation of data provided by the controller. In Flow views are cleanly decoupled from the rest of the MVC framework. This allows you to either take advantage of Fluid (Flow’s template engine), write your own custom PHP view class or use almost any other template engine by writing a thin wrapper building a bridge between Flow’s interfaces and the template engine’s functions. In this tutorial we focus on Fluid-based templates as this is what you usually want to use.

Resources

Before we design our first Fluid template we need to spend a thought on the resources our template is going to use (I’m talking about all the images, style sheets and javascript files which are referred to by your HTML code). You remember that only the Web directory is accessible from the web, right? And the resources are part of the package and thus hidden from the public. That’s why Flow comes with a powerful resource manager whose main task is to manage access to your package’s resources.

The deal is this: All files which are located in the public resources directory of your package will automatically be mirrored to somewhere that is publicly accessible. By default, Flow just symlinks those files to the public resources directory below the Web folder.

Let’s take a look at the directory layout of the Acme.Blog package:

Directory structure of a Flow package
Directory Description
Classes/ All the .php class files of your package
Documentation/ The package’s manual and other documentation
Resources/ Top folder for resources
Resources/Public/ Public resources - will be mirrored to the Web directory
Resources/Private/ Private resources - won’t be mirrored to the Web directory

No matter what files and directories you create below Resources/Public/ - all of them will, by default, be symlinked to Web/_Resources/Static/Packages/Acme.Blog/ on the next hit.

Tip

There are more possible directories in a package and we do have some conventions for naming certain sub directories. All that is explained in fine detail in Part III.

Important

For the blog example in this tutorial we created some style sheet to make it more appealing. If you’d like the examples to use those styles, then it’s time to copy Resources/Public/ from the git repository (https://github.com/neos/Acme.Blog) to your blog’s public resources folder (Packages/Application/Acme.Blog/Resources/Public/).

Layouts

Fluid knows the concepts of layouts, templates and partials. Usually all of them are just plain HTML files which contain special tags known by the Fluid template view. The following figure illustrates the use of layout, template and partials in our blog example:

Layout, Template and Partial

Layout, Template and Partial

A Fluid layout provides the basic layout of the output which is supposed to be shared by multiple templates. You will use the same layout throughout this tutorial - only the templates will change depending on the current controller and action. Elements shared by multiple templates can be extracted as a partial to assure consistency and avoid duplication.

Let’s build a simple layout for your blog. You only need to adjust the file called Default.html inside the Acme.Blog/Resources/Private/Layouts directory to contain the following code:

Resources/Private/Layouts/Default.html:

<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="utf-8">
    <title>{blog.title} - Flow Blog Example</title>
    <link rel="stylesheet" href="../../Public/Styles/App.css" type="text/css" />
</head>
<body>

    <header>
        <f:if condition="{blog}">
            <f:link.action action="index" controller="Post">
                <h1>{blog.title}</h1>
            </f:link.action>
            <p class="description">{blog.description -> f:format.crop(maxCharacters: 80)}</p>
        </f:if>
    </header>

    <div id="content">
        <f:flashMessages class="flashmessages" />
        <f:render section="MainContent" />
    </div>

    <footer>
        <a href="http://flow.neos.io">
            Powered by Flow
        </a>
    </footer>

</body>
</html>

Tip

If you don’t want to download the stylesheet mentioned above, you can import it directly from the github repository, replacing ../../Public/Styles./App.css` with https://raw.githubusercontent.com/neos/Acme.Blog/master/Resources/Public/Styles/App.css Of course you can also just remove the whole <link rel="stylesheet" ... line if you don’t care about style.

On first sight this looks like plain HTML code, but you’ll surely notice the various <f: ... > tags. Fluid provides a range of view helpers which are addressed by these tags. By default they live in the f namespace resulting in tags like <f:if> or <f:link.action>. You can define your own namespaces and even develop your own view helpers, but for now let’s look at what you used in your layout:

The first thing to notice is <f:if>, a Fluid tag in <body>. This tag instructs Fluid to render its content only if its condition is true. In this case, condition="{blog}" tells the <f:if> tag to render only if blog is set.

Look at that condition again, noting the curly braces: {blog}. This is a variable accessor. It is very similar to some Fluid markup that we skipped over in <head>:

Resources/Private/Layouts/Default.html:

<title>{blog.title} - Flow Blog Example</title>

As you will see in a minute, Fluid allows your controller to define variables for the template view. In order to display the blog’s name, you’ll need to make sure that your controller assigns the current Blog object to the template variable blog. The value of such a variable can be inserted anywhere in your layout, template or partial by inserting the variable name wrapped by curly braces. However, in the above case blog is not a value you can output right away – it’s an object. Fortunately Fluid can display properties of an object which are accessible through a getter function: to display the blog title, you just need to note down {blog.title} and Fluid will internally call the getTitle() method of the Blog instance.

We’ve looked at two kinds of Fluid syntax: tag-style view helpers (<f:if>), and variable accessors ({blog.title}). Another kind of Fluid syntax is an alternative way to address view helpers, the view helper shorthand syntax:

Resources/Private/Layouts/Default.html:

{blog.description -> f:format.crop(maxCharacters: 80)}

{f:format.crop(...)}` instructs Fluid to crop the given value (in this case the Blog’s description). With the maxCharacters argument the description will be truncated if it exceeds the given number of characters. The generated HTML code will look something like this:

Resources/Private/Layouts/Default.html:

This is a very long description that will be cropped if it exceeds eighty charac...

If you look at the remaining markup of the layout you’ll find more uses of view helpers, including flashMessages. It generates an unordered list with all flash messages. Well, maybe you remember this line in the createAction of our PostController:

$this->addFlashMessage('Created a new post.');

Flash messages are a great way to display success or error messages to the user beyond a single request. And because they are so useful, Flow provides a FlashMessageContainer with some helper methods and Fluid offers the flashMessages view helper. Therefore, if you create a new post, you’ll see the message Your new post was created at the top of your blog index on the next hit.

There’s only one view helper you need to know about before proceeding with our first template, the render view helper:

Resources/Private/Layouts/Default.html:

<f:render section="MainContent" />

This tag tells Fluid to insert the section MainContent defined in the current template at this place. For this to work there must be a section with the specified name in the template referring to the layout – because that’s the way it works: A template declares which layout it is based on, defines sections which in return are included by the layout. Confusing? Let’s look at a concrete example.

Templates

Templates are, as already mentioned, tailored to a specific action. The action controller chooses the right template automatically according to the current package, controller and action - if you follow the naming conventions. Let’s replace the automatically generated template for the Post controller’s index action in Acme.Blog/Resources/Private/Templates/Post/Index.html with some more meaningful HTML:

Resources/Private/Templates/Post/Index.html:

<f:layout name="Default" />

<f:section name="MainContent">
    <f:if condition="{blog.posts}">
        <f:then>
            <ul>
                <f:for each="{blog.posts}" as="post">
                    <li class="post">
                        <f:render partial="PostActions" arguments="{post: post}"/>
                        <h2>
                            <f:link.action action="show" arguments="{post: post}">{post.subject}</f:link.action>
                        </h2>
                        <f:render partial="PostMetaData" arguments="{post: post}"/>
                    </li>
                </f:for>
            </ul>
        </f:then>
        <f:else>
            <p>No posts created yet.</p>
        </f:else>
    </f:if>
    <p>
        <f:link.action action="new">Create a new post</f:link.action><
    /p>
</f:section>

There you have it: In the first line of your template there’s a reference to the “Default” layout. All HTML code is wrapped in a <f:section> tag. Even though this is the way you usually want to design templates, you should know that using layouts is not mandatory – you could equally put all your code into one template and omit the <f:layout> and <f:section> tags.

The main job of this template is to display a list of the most recent posts. An <f:if> condition makes sure that the list of posts is only rendered if blog actually contains posts. But currently the view doesn’t know anything about a blog - you need to adapt the the PostController to assign the current blog:

*Classes/Acme/Blog/Controller/PostController.php*:
/**
 * @return void
 */
public function indexAction() {
    $blog = $this->blogRepository->findActive();
    $this->view->assign('blog', $blog);
}

To fully understand the above code you need to know two facts:

  • $this->view is automatically set by the action controller and points to a Fluid template view.
  • if an action method returns NULL, the controller will automatically call $this->view->render() after executing the action.

But soon you’ll see that we need the current Blog in all of our actions, so how to assign it to the view without repeating the same code over and over again? With ease: We just assign it as soon as the view is initialized:

*Classes/Acme/Blog/Controller/PostController.php*:
/**
 * @param ViewInterface $view
 * @return void
 */
protected function initializeView(ViewInterface $view) {
    $blog = $this->blogRepository->findActive();
    $this->view->assign('blog', $blog);
}

/**
 * @return void
 */
public function indexAction() {
}

The initializeView method is called before each action, so it provides a good opportunity to assign values to the view that should be accessible from all actions. But make sure only to use it for truly global values in order not to waste memory for unused data.

After creating the folder Resources/Private/Partials/ add the following two partials:

*Resources/Private/Partials/PostMetaData.html*:
<p class="metadata">
    Published on {post.date -> f:format.date(format: 'Y-m-d')} by {post.author}
</p>

Resources/Private/Partials/PostActions.html:

<ul class="actions">
    <li>
        <f:link.action action="edit" arguments="{post: post}">Edit</f:link.action>
    </li>
    <li>
        <f:form action="delete" arguments="{post: post}">
            <f:form.submit name="delete" value="Delete" />
        </f:form>
    </li>
</ul>

The PostMetaData partial renders date and author of a post. The PostActions partial an edit link and a button to delete the current post. Both are used as well in the list view (indexAction) as well as in the detail view (showAction) of the post and Partials allow us to easily re-use the parts without having to duplicate markup.

Now you should now see the list of recent posts by accessing http://dev.tutorial.local/acme.blog/post:

The list of blog posts

The list of blog posts

To create new posts and edit existing ones from the web browser, we need to create Forms:

Forms

Create a New Post

Time to create a form which allows you to enter details for a new post. The first component you need is the newAction whose sole purpose is displaying the form:

Classes/Acme/Blog/Controller/PostController.php:

/**
 * Displays the "Create Post" form
 *
 * @return void
 */
public function newAction() {
}

No code? What will happen is this: the action controller selects the New.html template and assigns it to $this->view which will automatically be rendered after newAction has been called. That’s enough for displaying the form. The current blog is already assigned in initializeView() allowing the blog title and description to be rendered in our header (defined in Default.html). Otherwise those would be empty.

The second component is the actual form. Adjust the template New.html in the Resources/Private/Templates/Post/ folder:

Resources/Private/Templates/Post/New.html:

<f:layout name="Default" />

<f:section name="MainContent">
    <h2>Create new post</h2>
    <f:form action="create" objectName="newPost">
        <f:form.hidden property="blog" value="{blog}" />

        <label for="post-author">Author</label>
        <f:form.textfield property="author" id="post-author" />

        <label for="post-subject">Subject</label>
        <f:form.textfield property="subject" id="post-subject" />

        <label for="post-content">Content</label>
        <f:form.textarea property="content" rows="5" cols="30" id="post-content" />

        <f:form.submit name="submit" value="Publish Post" />
    </f:form>
</f:section>

Here is how it works: The <f:form> view helper renders a form tag. Its attributes are similar to the action link view helper you might have seen in previous examples: action specifies the action to be called on submission of the form, controller would specify the controller and package the package respectively. If controller or package are not set, the URI builder will assume the current controller or package respectively. objectName finally specifies the name of the action method argument which will receive the form values, in this case “newPost”.

It is important to know that the whole form is (usually) bound to one object and that the values of the form’s elements become property values of this object. In this example the form contains (property) values for a post object. The form’s elements are named after the class properties of the Post domain model: blog, author, subject and content. Let’s look at the createAction again:

Note

Mind that newPost is not assigned to the view in this example. Assigning this object is only needed if you have set default values to your model properties. So if you for example have a protected $hidden = TRUE definition in your model, a <f:form.checkbox property="hidden" /> will not be checked by default, unless you instantiate $newPost in your index action and assign it to the view.

Classes/Acme/Blog/Controller/PostController.php:

/**
 * Creates a new post
 *
 * @param Post $newPost
 * @return void
 */
public function createAction(Post $newPost) {
    $this->postRepository->add($newPost);
    $this->addFlashMessage('Created a new post.');
    $this->redirect('index');
}

It’s important that the createAction uses the type hint Post (which expands to \Acme\Blog\Domain\Model\Post) and that it comes with a proper @param annotation because this is how Flow determines the type to which the submitted form values must be converted. Because this action requires a Post it gets a post (object) - as long as the property names of the object and the form match.

Time to test your new newAction and its template – click on the little plus sign above the first post lets the newAction render this form:

Form to create a new post

Form to create a new post

Enter some data and click the submit button:

A new post has been created

A new post has been created

You should now find your new post in the list of posts.

Edit a Post

While you’re dealing with forms you should also create form for editing an existing post. The editAction will display this form.

This is pretty straight forward: we already added a link to each post with the PostActions.html partial:

*Resources/Private/Templates/Post/Index.html*:
<ul class="actions">
    <li>
        <f:link.action action="edit" arguments="{post: post}">Edit</f:link.action>
    </li>
    <li>
        <f:form action="delete" arguments="{post: post}">
            <f:form.submit name="delete" value="Delete" />
        </f:form>
    </li>
</ul>

This renders an “Edit” link that points to the editAction of the PostController. Below is a little form with just one button that triggers the deleteAction().

Note

The reason why the deleteAction() is invoked via a form instead of a link is because Flow follows the HTTP 1.1 specification that suggests that called “safe request methods” (usually GET or HEAD requests) should not change the server state. See Part III - Validation for more details. The editAction() just displays the Post edit form, so it can be called via GET requests.

Adjust the template Templates/Post/Edit.html and insert the following HTML code:

Resources/Private/Templates/Post/Edit.html:

<f:layout name="Default" />

<f:section name="MainContent">
    <h2>Edit post "{post.subject}"</h2>
    <f:form action="update" object="{post}" objectName="post">
        <label for="post-author">Author</label>
        <f:form.textfield property="author" id="post-author" />

        <label for="post-subject">Subject</label>
        <f:form.textfield property="subject" id="post-subject" />

        <label for="post-content">Content</label>
        <f:form.textarea property="content" rows="5" cols="30" id="post-content" />

        <f:form.submit name="submit" value="Update Post" />
    </f:form>
</f:section>

Most of this should already look familiar. However, there is a tiny difference to the new form you created earlier: in this edit form you added object="{post}" to the <f:form> tag. This attribute binds the variable {post} to the form and it simplifies the further definition of the form’s elements. Each element – in our case the text box and the text area – comes with a property attribute declaring the name of the property which is supposed to be displayed and edited by the respective element.

Because you specified property="author" for the text box, Fluid will fetch the value of the post’s author property and display it as the default value for the rendered text box. The resulting input tag will also contain the name "author" due to the property attribute you defined. The id attribute only serves as a target for the label tag and is not required by Fluid.

What’s missing now is a small adjustment to the PHP code displaying the edit form:

Classes/Acme/Blog/Controller/PostController.php:

/**
 * Displays the "Edit Post" form
 *
 * @param Post $post
 * @return void
 */
public function editAction(Post $post) {
    $this->view->assign('post', $post);
}

Enough theory, let’s try out the edit form in practice. A click on the edit link of your list of posts should result in a screen similar to this:

The edit form for a post

The edit form for a post

When you submit the form you call the updateAction:

Classes/Acme/Blog/Controller/PostController.php:

/**
 * Updates a post
 *
 * @param Post $post
 * @return void
 */
public function updateAction(Post $post) {
    $this->postRepository->update($post);
    $this->addFlashMessage('Updated the post.');
    $this->redirect('index');
}

Quite easy as well, isn’t it? The updateAction expects the edited post as its argument and passes it to the repository’s update method (note that we used the PostRepository!). Before we disclose the secret how this magic actually works behind the scenes try out if updating the post really works:

The post has been edited

The post has been edited

A Closer Look on Updates

Although updating objects is very simple on the user’s side (that’s where you live), it is a bit complex on behalf of the framework. You may skip this section if you like - but if you dare to take a quick look behind the scenes to get a better understanding of the mechanism behind the updateAction read on ...

The updateAction expects one argument, namely the edited post. “Edited post” means that this is a Post object which already contains the values submitted by the edit form.

These modifications will not be persisted automatically. To persist the changes to the post object, call the PostRepository’s update method. It schedules an object for the dirty check at the end of the request.

If all these details didn’t scare you, you might now ask yourself how Flow could know that the updateAction expects a modified object and not the original? Great question. And the answer is – literally – hidden in the form generated by Fluid’s form view helper:

<form action="/acme.blog/post/update" method="post">
    ...
    <input type="hidden" name="post[__identity]" value="7825fe4b-33d9-0522-a3f2-02833f9084ab" />
    ...
</form>

Fluid automatically renders a hidden field containing information about the technical identity of the form’s object, if the object is an original, previously retrieved from a repository.

On receiving a request, the MVC framework checks if a special identity field (such as the above hidden field) is present and if further properties have been submitted. This results in three different cases:

Create, Show, Update detection
Situation Case Consequence
identity missing, properties present New / Create Create a completely new object and set the given properties
identity present, properties missing Show / Delete / ... Retrieve original object with given identifier
identity present, properties present Edit / Update Retrieve original object, and set the given properties

Because the edit form contained both identity and properties, Flow prepared an instance with the given properties for our updateAction.