23 KiB
Templates
Introduction
SilverStripe templates consist of HTML code augmented with special control codes, described below. Because of this, you can have as much control of your site's HTML code as you like.
Because the SilverStripe templating language is a string processing language it can therefore be used to make other text-based data formats, such as XML or RTF.
Here is a very simple template:
:::ss
<html>
<head>
<% base_tag %>
<title>$Title</title>
<% require themedCSS(screen) %>
</head>
<body>
<header>
<h1>Bob's Chicken Shack</h1>
</header>
<% with $CurrentMember %>
<p>Welcome $FirstName $Surname.</p>
<% end_with %>
<% if Dishes %>
<ul>
<% loop Dishes %>
<li>$Title ($Price.Nice)</li>
<% end_loop %>
</ul>
<% end_if %>
<% include Footer %>
</body>
</html>
More sophisticated use of templates for pages managed in the CMS, including template inheritance and navigation loops is documented in the page types topic.
Template elements
Variables
Variables are things you can use in a template that grab data from the page and put in the HTML document. For example:
:::ss
$Title
This inserts the value of the Title field of the page being displayed in place of $Title. This type of variable is called a property. It is often something that can be edited in the CMS. Variables can be chained together, and include arguments.
:::ss
$Property
$Property(param)
$Property.SubProperty
These variables will call a method/field on the object and insert the returned value as a string into the template.
$Propertywill call$obj->Property()(or the field$obj->Property)$Property(param)will call$obj->Property("param")$Property.SubPropertywill call$obj->Property()->SubProperty()(or field equivalents)
If a variable returns a string, that string will be inserted into the template. If the variable returns an object, then
the system will attempt to render the object through its forTemplate() method. If the forTemplate() method has not been
defined, the system will return an error.
SilverStripe provides lots of properties and methods. For more details on built-in page controls and variables, see http://doc.silverstripe.org/framework/en/reference/built-in-page-controls
Escaping
Sometimes you will have template tags which need to roll into one another. This can often result in SilverStripe looking
for a "FooBar" value rather than a "Foo" and then "Bar" value or when you have a string directly before or after the
variable you will need to escape the specific variable. In the following example $Foo is 3.
:::ss
$Foopx // returns "" (as it looks for a Foopx value)
{$Foo}px // returns "3px" (CORRECT)
Or when having a $ sign in front of the variable
:::ss
$$Foo // returns ""
${$Foo} // returns "$3"
You can also use a backslash to escape the name of the variable, such as:
:::ss
$Foo // returns "3"
\$Foo // returns "$Foo"
Includes
Within SilverStripe templates we have the ability to include other templates from the Includes directory using the SS
'include' tag. For example, the following code would include the Includes/SideBar.ss code:
:::ss
<% include SideBar %>
The "include" tag can be particularly helpful for nested functionality. In this example, the include only happens if a variable is true
:::ss
<% if CurrentMember %>
<% include MembersOnlyInclude %>
<% end_if %>
Includes can't directly access the parent scope of the scope active when the include is included. However you can pass arguments to the include, which are available on the scope top within the include
:::ss
<% with CurrentMember %>
<% include MemberDetails PageTitle=$Top.Title, PageID=$Top.ID %>
<% end_with %>
You can also perform includes using the Requirements Class via the template controls. See the section on Includes in Templates for more details and examples.
:::ss
<% require themedCSS(LeftNavMenu) %>
Including CSS and JavaScript files (a.k.a "Requirements")
See CSS and Javascript topics for individual including of files and requirements for good examples of including both Javascript and CSS files.
Conditional Logic
You can conditionally include markup in the output. That is, test for something that is true or false, and based on that test, control what gets output.
The simplest if block is to check for the presence of a value.
:::ss
<% if $CurrentMember %>
<p>You are logged in as $CurrentMember.FirstName $CurrentMember.Surname.</p>
<% end_if %>
The following compares a page property called MyDinner with the value in
quotes, kipper, which is a literal. If true, the text inside the if-block
is output.
:::ss
<% if $MyDinner="kipper" %>
Yummy, kipper for tea.
<% end_if %>
Note that inside a tag like this, variables should have a '$' prefix, and literals should have quotes. SilverStripe 2.4 didn't include the quotes or $ prefix, and while this still works, we recommend the new syntax as it is less ambiguous.
This example shows the use of the else option. The markup after else is
output if the tested condition is not true.
:::ss
<% if $MyDinner="kipper" %>
Yummy, kipper for tea
<% else %>
I wish I could have kipper :-(
<% end_if %>
This example shows the user of else_if. There can be any number of else_if
clauses. The conditions are tested from first to last, until one of them is true,
and the markup for that condition is used. If none of the conditions are true,
the markup in the else clause is used, if that clause is present.
:::ss
<% if $MyDinner="quiche" %>
Real men don't eat quiche
<% else_if $MyDinner=$YourDinner %>
We both have good taste
<% else %>
Can I have some of your chips?
<% end_if %>
This example shows the use of not to negate the test.
:::ss
<% if not $DinnerInOven %>
I'm going out for dinner tonight.
<% end_if %>
You can combine two or more conditions with || ("or"). The markup is used if
either of the conditions is true.
:::ss
<% if $MyDinner=="kipper" || $MyDinner=="salmon" %>
yummy, fish for tea
<% end_if %>
You can combine two or more conditions with && ("and"). The markup is used if
both of the conditions are true.
:::ss
<% if $MyDinner=="quiche" && $YourDinner=="kipper" %>
Lets swap dinners
<% end_if %>
Looping Over Lists
The <% loop %>...<% end_loop %> tag is used to iterate or loop over a
collection of items. For example:
:::ss
<ul>
<% loop $Children %>
<li>$Title</li>
<% end_loop %>
</ul>
This loops over the children of a page, and generates an unordered list showing
the Title property from each one. Note that $Title inside the loop refers
to the Title property on each object that is looped over, not the current page.
To refer to the current page's Title property inside the loop, you can do
$Up.Title. More about Up later.
Position Indicators
Inside the loop scope, there are many variables at your disposal to determine the current position in the list and iteration:
$Even,$Odd: Returns boolean, handy for zebra striping$EvenOdd: Returns a string, either 'even' or 'odd'. Useful for CSS classes.$First,$Last,$Middle: Booleans about the position in the list$FirstLast: Returns a string, "first", "last", or "". Useful for CSS classes.$Pos: The current position in the list (integer). Will start at 1.$TotalItems: Number of items in the list (integer)
Modulus and MultipleOf
$Modulus and $MultipleOf can help to build column layouts.
:::ss
$Modulus(value, offset) // returns an int
$MultipleOf(factor, offset) // returns a boolean.
The following example demonstrates how you can use $Modulus(4) to generate custom column names based on your loop statement. Note that this works for any control statement (not just children).
:::ss
<% loop Children %>
<div class="column-{$Modulus(4)}">
...
</div>
<% end_loop %>
Will return you column-3, column-2, column-1, column-0, column-3 etc. You can use these as styling hooks to float, position as you need.
You can also use $MultipleOf(value, offset) to help build columned layouts. In
this case we want to add a
after every 3th item.
:::ss
<% loop Children %>
<% if MultipleOf(3) %>
<br>
<% end_if %>
<% end_loop %>
Scope
In the <% loop %> section, we saw an example of two scopes. Outside the
<% loop %>...<% end_loop %>, we were in the scope of the page. But inside the
loop, we were in the scope of an item in the list. The scope determines where
the value comes from when you refer to a variable. Typically the outer scope of
a page type's layout template is the page that is currently being rendered.
The outer scope of an included template is the scope that it was included into.
Up
When we are in a scope, we sometimes want to refer to the scope outside the
<% loop %> or <% with %>. We can do that easily by using $Up. $Up takes
the scope back to the previous level. Take the following example:
:::ss
$Title
--
<% loop Children %>
$Title
$Up.Title
--
<% loop Children %>
$Title
$Up.Title
<% end_loop %>
<% end_loop %>
With a page structure (Blog -> Blog entry -> Child blog entry) the above will produce:
:::ss
Blog
--
Blog entry
Blog
--
Child blog entry
Blog entry
Top
While $Up provides us a way to go up 1 scope, $Top is a shortcut to jump to
the top most scope of the page. Using the previous example but expanded to
include $Top:
:::ss
$Title
--
<% loop Children %>
$Title
$Up.Title
$Top.Title
--
<% loop Children %>
$Title
$Up.Title
$Top.Title
<% end_loop %>
<% end_loop %>
Will produce
:::ss
Blog
--
Blog entry
Blog
Blog
--
Child blog entry
Blog entry
Blog
With
The <% with %>...<% end_with %> tag lets you introduce a new scope. Consider
the following example:
:::ss
<% with $CurrentMember %>
Hello $FirstName, welcome back. Your current balance is $Balance.
<% end_with %>
Outside the <% with %>...<% end_with %>, we are in the page scope. Inside it,
we are in the scope of $CurrentMember. We can refer directly to properties and
methods of that member. So $FirstName is equivalent to $CurrentMember.FirstName.
This keeps the markup clean, and if the scope is a complicated expression we don't
have to repeat it on each reference of a property.
<% with %> also lets us use a collection as a scope, so we can access
properties of the collection itself, instead of iterating over it. For example:
:::ss
$Children.Length
returns the number of items in the $Children collection.
Pagination
Lists can be paginated, and looped over to generate pagination. For this to
work, the list needs to be wrapped in a [api:PaginatedList]. The process is
explained in detail on the "pagination" howto.
The list is split up in multiple "pages", each . Note that "page" is this context
does not necessarily refer to a Page class (although it often happens to be one).
$MoreThanOnePage: Returns true when we have a multi-page list, restricted with a limit.$NextLink,$PrevLink: This returns links to the next and previous page in a multi-page datafeed. They will return blank if there's no appropriate page to go to, so$PrevLinkwill return blank when you're on the first page.$CurrentPage: Current page iterated on$TotalPages: Total number of pages$TotalItems: This returns the total number of items across all pages.$Pages: The actual (limited) list of records, use in an inner loop$PageNum: Page number, starting at 1 (within$Pages)$Link: Links to the current controller URL, setting this page as current via a GET parameter (within$Pages)$CurrentBool: Returns true if you're currently on that page (within$Pages)
Formatting and Casting
Properties are usually auto-escaped in templates to ensure consistent representation,
and avoid format clashes like displaying unescaped ampersands in HTML.
By default, values are escaped as XML, which is equivalent to HTML for this purpose.
There's some exceptions to this rule, see the "security" topic.
In case you want to explicitly allow unescaped HTML input,
the property can be cast as [api:HTMLText].
The following example takes the Content field in a SiteTree class,
which is of this type. It forces the content into an explicitly escaped format.
:::ss
$Content.XML // transforms e.g. "<em>alert</em>" to "<em>alert</em>"
Apart from value formatting, there's many methods to transform them as well,
For example, the built in $Now placeholder is an instance of [api:Date],
and returns the current date in a standard system format.
Since its an object, you can use the helper methods to return other formats:
:::ss
$Now.Year // Current year
$Now.Nice // Localized date, based on i18n::get_locale()
See data-types for more information.
Translations
Translations are easy to use with a template, and give access to SilverStripe's translation facilities. Here is an example:
<%t Member.WELCOME 'Welcome {name} to {site}' name=$Member.Name site="Foobar.com" %>
Pulling apart this example we see:
Member.WELCOMEis an identifier in the translation system, for which different translations may be available. This string may include named placeholders, in braces.'Welcome {name} to {site}'is the default string used, if there is no translation for Member.WELCOME in the current locale. This contains named placeholders.name=$Member.Nameassigns a value to the named placeholdername. This value is substituted into the translation string wherever{name}appears in that string. In this case, it is assigning a value from a propertyMember.Namesite="Foobar.com"assigns a literal value to another named placeholder,site.
Comments
Using standard HTML comments is supported. These comments will be included in the published site.
:::ss
$EditForm <!-- Some public comment about the form -->
However you can also use special SilverStripe comments which will be stripped out of the published site. This is useful for adding notes for other developers but for things you don't want published in the public html.
:::ss
$EditForm <%-- Some hidden comment about the form --%>
Partial Caching
Partial caching lets you define blocks of your template that are cached for better performance. See Partial Caching for more information.
Base Tag
The <% base_tag %> placeholder is replaced with the HTML base element. Relative links within a document (such as <img src="someimage.jpg" />) will become relative to the URI specified in the base tag. This ensures the browser knows where
to locate your site’s images and css files. So it is a must for templates!
It renders in the template as <base href="http://www.mydomain.com" /><!--[if lte IE 6]></base><![endif]-->
CurrentMember
Returns the currently logged in member, if there is one.
All of their details or any special Member page controls can be called on this.
Alternately, you can use <% if CurrentMember %> to detect whether someone has logged
in.
:::ss
<% if CurrentMember %>
Welcome Back, $CurrentMember.FirstName
<% end_if %>
Custom Template Variables and Controls
There are two ways you can extend the template variables you have available. You can create a new database field in your
$db or if you do not need the variable to be editable in the cms you can create a function which returns a value in your
Page.php class.
:::php
// mysite/code/Page.php
public function MyCustomValue() {
return "Hi, this is my site";
}
Will give you the ability to call $MyCustomValue from anywhere in your template.
:::ss
I've got one thing to say to you: <i>$MyCustomValue</i>
// output "I've got one thing to say to you: <i>Hi, this is my site</i>"
Your function could return a single value as above or it could be a subclass of [api:ArrayData] for example a
[api:DataObject] with many values then each of these could be accessible via a control loop
:::php
// ...
public function MyCustomValues() {
return new ArrayData(array("Hi" => "Kia Ora", "Name" => "John Smith"));
}
And now you could call these values by using
:::ss
<% with MyCustomValues %>
$Hi , $Name
<% end_with %>
// output "Kia Ora , John Smith"
Or by using the dot notation you would have
:::ss
$MyCustomValues.Hi , $MyCustomValues.Name
// output "Kia Ora , John Smith"
Side effects
All functions that provide data to templates must have no side effects, as the value is cached after first access. For example, this controller method
:::php
private $counter = 0;
public function Counter() {
$this->counter += 1;
return $this->counter;
}
and this template
:::ss
$Counter, $Counter, $Counter
will render as "1, 1, 1", not "1, 2, 3"
.typography style
By default, SilverStripe includes the theme/css/typography.css file into the Content area. So you should always include the
typography style around the main body of the site so both styles appear in the CMS and on the template. Where the main body of
the site is can vary, but usually it is included in the /Layout files. These files are included into the main Page.ss template
by using the $Layout variable so it makes sense to add the .typography style around $Layout.
:::ss
<div class="typography">
$Layout
</div>
Calling templates from PHP code
This is all very well and good, but how do the templates actually get called?
Templates do nothing on their own. Rather, they are used to render a particular object. All of the <% if %>, <%control %>,
and variable codes are methods or parameters that are called on that object. All that is necessary is
that the object is an instance of [api:ViewableData] (or one of its subclasses).
The key is [api:ViewableData::renderWith()]. This method is passed a For example, within the controller's default action,
there is an instruction of the following sort:
:::php
$controller->renderWith("TemplateName");
Here's what this line does:
- First
renderWith()constructs a new object:$template = new SSViewer("TemplateName"); [api:SSViewer]will take the content ofTemplateName.ss, and turn it into PHP code.- Then
renderWith()passes the controller to$template->process($controller); SSViewer::process()will execute the PHP code generated fromTemplateName.ssand return the results.
renderWith() returns a string - the populated template. In essence, it uses a template to cast an object to a string.
renderWith() can also be passed an array of template names. If this is done, then renderWith() will use the first
available template name.
Below is an example of how to implement renderWith. In the example below the page is rendered using the myAjaxTemplate
if the page is called by an ajax function (using [api:Director::is_ajax()]). Note that the index function is called by
default if it exists and there is no action in the url parameters.
:::php
class MyPage_Controller extends Page_Controller {
public function init(){
parent::init();
}
public function index() {
if(Director::is_ajax()) {
return $this->renderWith("myAjaxTemplate");
} else {
return Array();// execution as usual in this case...
}
}
}
Fragment Link rewriting
Fragment links are links with a "#" in them. A frequent use-case is to use fragment links to point to different sections of the current page. For example, we might have this in our template.
For, example, we might have this on http://www.example.com/my-long-page/
:::ss
<ul>
<li><a href="#section1">Section 1</a></li>
<li><a href="#section2">Section 2</a></li>
</ul>
So far, so obvious. However, things get tricky because of we have set our <base> tag to point to the root of your
site. So, when you click the first link you will be sent to http://www.example.com/#section1 instead of
http://www.example.com/my-long-page/#section1
In order to prevent this situation, the SSViewer template renderer will automatically rewrite any fragment link that doesn't specify a URL before the fragment, prefixing the URL of the current page. For our example above, the following would be created:
:::ss
<ul>
<li><a href="my-long-page/#section1">Section 1</a></li>
<li><a href="my-long-page/#section2">Section 2</a></li>
</ul>
There are cases where this can be unhelpful. HTML fragments created from Ajax responses are the most common. In these situations, you can disable fragment link rewriting like so:
:::php
SSViewer::setOption('rewriteHashlinks', false);
More Advanced Controls
Template variables and controls are just PHP properties and methods on the underlying controllers and model classes. We've just shown you the most common once, in practice you can use any public API on those classes, and extend them with your own. To get an overview on what's available to you, we recommend that you dive into the API docs for the following classes:
[api:Controller]: Generic controller class[api:DataObject]: Generic model class[api:ViewableData]: Underlying object class for pretty much anything displayable
Designing reusable templates
Although SilverStripe is ultimately flexible in how you create your templates, there's a couple of best practices. These will help you to design templates for modules, and make it easier for other site developers to integrate them into their own base templates.
- Most of your templates should be
Layouttemplates - Build your templates as a Theme so you can easily re-use and exchange them
- Your layout template should include a standard markup structure (
<div id="Layout">$Layout</div>) - Layout templates only include content that could be completely replaced by another module (e.g. a forum thread). It
might be infeasible to do this 100%, but remember that every piece of navigation that needs to appear inside
$Layoutwill mean that you have to customise templates when integrating the module. - Any CSS applied to layout templates should be flexible width. This means the surrounding root template can set its width independently.
- Don't include any navigation elements in your
Layouttemplates, they should be contained in the root template. - Break down your templates into groups of includes. Site integrators would then have the power to override individual includes, rather than entire templates.
For more information about templates go to the Advanced Templates page.