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Template Inheritance

Bundled within SilverStripe are default templates for any markup the framework outputs for things like Form templates, Emails or RSS Feeds. These templates are provided to make getting your site up and running quick with sensible defaults but it's easy to replace and customize SilverStripe (and add-on's) by providing custom templates in your own mysite/templates folder or in your themes/your_theme/templates folder.

Take for instance the GenericEmail template in SilverStripe. This is the HTML default template that any email created in SilverStripe is rendered with. It's bundled in the core framework at framework/templates/email/GenericEmail.ss.

Instead of editing that file to provide a custom template for your application, simply define a template of the same name in the mysite/templates/email folder or in the themes/your_theme/templates/email folder if you're using themes.

mysite/templates/email/GenericEmail.ss

$Body

<p>Thanks from Bob's Fantasy Football League.</p>

All emails going out of our application will have the footer Thanks from Bob's Fantasy Football Leaguee added.

As we've added a new file, make sure you flush your SilverStripe cache by visiting http://yoursite.com/?flush=1

Template inheritance works on more than email templates. All files within the templates directory including includes, layout or anything else from core (or add-on's) template directory can be overridden by being located inside your mysite/templates directory. SilverStripe keeps an eye on what templates have been overridden and the location of the correct template through a SS_TemplateManifest.

Template Manifest

The location of each template and the hierarchy of what template to use is stored within a SS_TemplateManifest instance. This is a serialized object containing a map of template names, paths and other meta data for each template and is cached in your applications TEMP_FOLDER for performance. For SilverStripe to find the GenericEmail template it does not check all your template folders on the fly, it simply asks the manifest.

The manifest is created whenever you flush your SilverStripe cache by appending ?flush=1 to any SilverStripe URL. For example by visiting http://yoursite.com/?flush=1. When your include the flush=1 flag, the manifest class will search your entire project for the appropriate .ss files located in template directory and save that information for later.

It will each and prioritize templates in the following priority:

  1. mysite (or other name given to site folder)
  2. themes
  3. modules
  4. framework.
Whenever you add or remove template files, rebuild the manifest by visiting `http://yoursite.com/?flush=1`. You can flush the cache from any page, (.com/home?flush=1, .com/admin?flush=1, etc.). Flushing the cache can be slow, so you only need to do it when you're developing new templates.

Nested Layouts through $Layout

SilverStripe has basic support for nested layouts through a fixed template variable named $Layout. It's used for storing top level template information separate to individual page layouts.

When $Layout is found within a root template file (one in templates), SilverStripe will attempt to fetch a child template from the templates/Layout directory. It will do a full sweep of your modules, core and custom code as it would if it was looking for a new root template.

This is better illustrated with an example. Take for instance our website that has two page types Page and HomePage.

Our site looks mostly the same across both templates with just the main content in the middle changing. The header, footer and navigation will remain the same and we don't want to replicate this work across more than one spot. The $Layout function allows us to define the child template area which can be overridden.

mysite/templates/Page.ss

<html>
<head>
    ..
</head>

<body>
    <% include Header %>
    <% include Navigation %>

    $Layout

    <% include Footer %>
</body>

mysite/templates/Layout/Page.ss

<p>You are on a $Title page</p>

$Content

mysite/templates/Layout/HomePage.ss

<h1>This is the homepage!</h1>

<blink>Hi!</blink>