Formatting and casting#

All objects that are being rendered in a template should be a ViewableData instance such as DataObject, DBField or Controller. From these objects, the template can include any method from the object in scope.

For instance, if we provide a DBHtmlText instance to the template we can call the FirstParagraph method. This will output the result of the DBHtmlText::FirstParagraph() method to the template.

<%-- app/templates/Page.ss --%>
$Content.FirstParagraph
<!-- returns the result of DBHtmlText::FirstParagragh() -->

$LastEdited.Format("d/m/Y")
<!-- returns the result of DBDatetime::Format("d/m/Y") -->

Any public method from the object in scope can be called within the template. If that method returns another ViewableData instance, you can chain the method calls.

$Content.FirstParagraph.NoHTML
<!-- "First Paragraph" -->

<p>Copyright {$Now.Year}</p>
<!-- "Copyright 2014" -->

<div class="$URLSegment.LowerCase">
<!-- <div class="about-us"> -->

ForTemplate#

When rendering an object to the template such as $Me the forTemplate method is called. This method can be used to provide default template for an object.

// app/src/Model/MyDataObject.php
namespace App\Model;

use SilverStripe\ORM\DataObject;

class MyDataObject extends DataObject
{
    public function forTemplate()
    {
        return 'Whatever is returned from here will be printed when $Me is used in a template';
    }
}

<%-- app/templates/App/Model/MyDataObject.ss --%>
<%-- This will call the forTemplate method: --%>
$Me

Casting#

Methods which return data to the template should either return an explicit object instance describing the type of content that method sends back, or provide a type in the $casting array for the object. When rendering that method to a template, Silverstripe CMS will ensure that the object is wrapped in the correct type and values are safely escaped.

namespace App\Model;

use SilverStripe\ORM\DataObject;

class MyDataObject extends DataObject
{
    private static $casting = [
        'Header' => 'HTMLText',
    ];

    public function getHeader()
    {
        return '<h1>This is my header</h1>';
    }
}

When calling $Header Silverstripe CMS now has the context that this method will contain HTML and escape the data accordingly.

Escaping#

Properties are usually auto-escaped in templates to ensure consistent representation, and avoid format clashes like displaying un-escaped ampersands in HTML. By default, values are escaped as XML, which is equivalent to HTML for this purpose.

For every field used in templates, a casting helper will be applied. This will first check for any casting helper on your model specific to that field, and will fall back to the default_cast config in case none are specified.

By default, ViewableData.default_cast is set to Text, which will ensure all fields have special characters HTML escaped by default.

The most common casting types are:

• Text Which is a plain text string, and will be safely encoded via HTML entities when placed into a template.
• Varchar which is the same as Text but for single-line text that should not have line breaks.
• HTMLFragment is a block of raw HTML, which should not be escaped. Take care to sanitise any HTML value saved into the database.
• HTMLText is a HTMLFragment, but has shortcodes enabled. This should only be used for content that is modified via a TinyMCE editor, which will insert shortcodes.
• Int for integers.
• Decimal for floating point values.
• Boolean For boolean values.
• Datetime for date and time.

See the Model data types and casting section for instructions on configuring your model to declare casting types for fields.

Escape methods in templates#

Within the template, fields can have their encoding customised at a certain level with format methods. See DBField for the specific implementation, but they will generally follow the below rules:

• $Field with no format method supplied will correctly cast itself for the HTML template, as defined by the casting helper for that field. In most cases this is the best method to use for templates.
• $Field.XML Will invoke htmlentities on special characters in the value, even if it's already cast as HTML.
• $Field.ATT will ensure the field is XML encoded for placement inside a HTML element property. This will invoke htmlentities on the value (even if already cast as HTML) and will escape quotes.
• Field.JS will cast this value as a JavaScript string. For example var fieldVal = '$Field.JS'; can be used in JavaScript defined in templates to encode values safely.
• $Field.CDATA will cast this value safely for insertion as a literal string in an XML file. e.g. <element>$Field.CDATA</element> will ensure that the <element> body is safely escaped as a string.

Cast summary methods#

Certain subclasses of DBField also have additional summary or manipulations methods, each of which can be chained in order to perform more complicated manipulations.

For instance, The following class methods can be used in templates for the below types:

Text / HTMLText methods:

• $Plain Will convert any HTML to plain text version. For example, could be used for plain-text version of emails.
• $LimitSentences(<num>) Will limit to the first <num> sentences in the content. If called on HTML content this will have all HTML stripped and converted to plain text.

Related lessons#

• Dealing with arbitrary template data