How to extend the CMS interface#

Introduction#

The CMS interface works just like any other part of your website: It consists of PHP controllers, templates, CSS stylesheets and JavaScript. Because it uses the same base elements, it is relatively easy to extend.

As an example, we're going to add a permanent "bookmarks" link list to popular pages into the main CMS menu. A page can be bookmarked by a CMS author through a simple checkbox.

For a deeper introduction to the inner workings of the CMS, please refer to our guide on CMS Architecture.

Overload a CMS template#

If you place a template with an identical name into your application template directory (usually mysite/templates/), it'll take priority over the built-in one.

CMS templates are inherited based on their controllers, similar to subclasses of the common Page object (a new PHP class MyPage will look for a MyPage.ss template). We can use this to create a different base template with LeftAndMain.ss (which corresponds to the LeftAndMain PHP controller class).

Copy the template markup of the base implementation at framework/admin/templates/Includes/LeftAndMain_Menu.ss into mysite/templates/Includes/LeftAndMain_Menu.ss. It will automatically be picked up by the CMS logic. Add a new section into the <ul class="cms-menu-list">

	...
	<ul class="cms-menu-list">
		<!-- ... -->
		<li class="bookmarked-link first">
			<a href="admin/pages/edit/show/1">Edit "My popular page"</a>
		</li>
		<li class="bookmarked-link last">
			<a href="admin/pages/edit/show/99">Edit "My other page"</a>
		</li>
	</ul>
	...

hardcoded links underneath the left-hand menu. We'll make these dynamic further down.

Include custom CSS in the CMS#

In order to show the links a bit separated from the other menu entries, we'll add some CSS, and get it to load with the CMS interface. Paste the following content into a new file called mysite/css/BookmarkedPages.css:

	.bookmarked-link.first {margin-top: 1em;}

configuration value.

	LeftAndMain:
	  extra_requirements_css:
	    - mysite/css/BookmarkedPages.css

Now we'll define which pages are actually bookmarked, a flag that is stored in the database. For this we need to decorate the page record with a DataExtension. Create a new file called mysite/code/BookmarkedPageExtension.php and insert the following code.

	<?php

	class BookmarkedPageExtension extends DataExtension {

		private static $db = array(
			'IsBookmarked' => 'Boolean'
		);

		public function updateCMSFields(FieldList $fields) {
			$fields->addFieldToTab('Root.Main',
				new CheckboxField('IsBookmarked', "Show in CMS bookmarks?")
			);
		}
	}

	SiteTree:
	  extensions:
	    - BookmarkedPageExtension

Refresh the CMS, open a page for editing and you should see the new checkbox.

Retrieve the list of bookmarks from the database#

One piece in the puzzle is still missing: How do we get the list of bookmarked pages from the database into the template we've already created (with hardcoded links)? Again, we extend a core class: The main CMS controller called LeftAndMain.

Add the following code to a new file mysite/code/BookmarkedLeftAndMainExtension.php;

	<?php

	class BookmarkedPagesLeftAndMainExtension extends LeftAndMainExtension {

		public function BookmarkedPages() {
			return Page::get()->filter("IsBookmarked", 1);
		}
	}

	LeftAndMain:
	  extensions:
	    - BookmarkedPagesLeftAndMainExtension

Find the <ul> you created earlier in mysite/admin/templates/LeftAndMain.ss and replace it with the following:

	<ul class="cms-menu-list">
		<!-- ... -->
		<% loop $BookmarkedPages %>
		<li class="bookmarked-link $FirstLast">
			<li><a href="admin/pages/edit/show/$ID">Edit "$Title"</a></li>
		</li>
		<% end_loop %>
	</ul>

CMS actions follow a principle similar to the CMS fields: they are built in the backend with the help of FormFields and FormActions, and the frontend is responsible for applying a consistent styling.

The following conventions apply:

• New actions can be added by redefining getCMSActions, or adding an extension with updateCMSActions.
• It is required the actions are contained in a FieldSet (getCMSActions returns this already).
• Standalone buttons are created by adding a top-level FormAction (no such button is added by default).
• Button groups are created by adding a top-level CompositeField with FormActions in it.
• A MajorActions button group is already provided as a default.
• Drop ups with additional actions that appear as links are created via a TabSet and Tabs with FormActions inside.
• A ActionMenus.MoreOptions tab is already provided as a default and contains some minor actions.
• You can override the actions completely by providing your own getAllCMSFields.

Let's walk through a couple of examples of adding new CMS actions in getCMSActions.

First of all we can add a regular standalone button anywhere in the set. Here we are inserting it in the front of all other actions. We could also add a button group (CompositeField) in a similar fashion.

	$fields->unshift(FormAction::create('normal', 'Normal button'));

already present in the FieldList.

	$fields->fieldByName('MajorActions')->push(FormAction::create('grouped', 'New group button'));

infrequently used minor actions.

	$fields->addFieldToTab('ActionMenus.MoreOptions', FormAction::create('minor', 'Minor action'));

TabSet.

	$fields->addFieldToTab('ActionMenus.MyDropUp', FormAction::create('minor', 'Minor action in a new drop-up'));

Empty tabs will be automatically removed from the FieldList to prevent clutter. [/hint]

To make the actions more user-friendly you can also use alternating buttons as detailed in the CMS Alternating Button how-to.

Implementing handlers#

Your newly created buttons need handlers to bind to before they will do anything. To implement these handlers, you will need to create a LeftAndMainExtension and add applicable controller actions to it:

	class CustomActionsExtension extends LeftAndMainExtension {
		
		private static $allowed_actions = array(
        	'sampleAction'
    	);
    	
    	public function sampleAction()
    	{
    		// Create the web
    	}
    	
    }
    

The extension then needs to be registered:

	LeftAndMain:
		extensions:
			- CustomActionsExtension
			

	$fields->push(FormAction::create('sampleAction', 'Perform Sample Action'));

In a few lines of code, we've customised the look and feel of the CMS.

While this example is only scratching the surface, it includes most building blocks and concepts for more complex extensions as well.

Related#

• Reference: CMS Architecture
• Reference: Layout
• Rich Text Editing
• CMS Alternating Button