Shortcodes#

The ShortcodeParser API is simple parser that allows you to map specifically formatted content to a callback to transform them into something else. You might know this concept from forum software which don't allow you to insert direct HTML, instead resorting to a custom syntax.

In the CMS, authors often want to insert content elements which go beyond standard formatting, at an arbitrary position in their WYSIWYG editor. Shortcodes are a semi-technical solution for this. A good example would be embedding a 3D file viewer or a Google Map at a certain location.

$text = '<h1>My Map</h1>[map]'

// Will output
// <h1>My Map</h1><iframe ..></iframe>

Here's some syntax variations:

[my_shortcode]

[my_shortcode/]

[my_shortcode,myparameter="value"]

[my_shortcode,myparameter="value"]Enclosed Content[/my_shortcode]

Shortcodes are automatically parsed on any database field which is declared as HTMLValue or DBHTMLText, when rendered into a template. This means you can use shortcodes on common fields like SiteTree.Content, and any other DataObject::$db definitions of these types.

Other fields can be manually parsed with shortcodes through the parse method.

use SilverStripe\View\Parsers\ShortcodeParser;

$text = 'My awesome [my_shortcode] is here.';
ShortcodeParser::get_active()->parse($text);

Defining custom shortcodes#

First we need to define a callback for the shortcode.

// app/src/ShortCode/MyShortCodeProvider.php
namespace App\ShortCode;

class MyShortCodeProvider
{
    public static function parseMyShortCode($arguments, $content = null, $parser = null, $tagName = null)
    {
        return '<em>' . $tagName . '</em> ' . $content . '; ' . count($arguments) . ' arguments.';
    }
}

These parameters are passed to the parseMyShortCode callback:

• Any parameters attached to the shortcode as an associative array (keys are lower-case).
• Any content enclosed within the shortcode (if it is an enclosing shortcode). Note that any content within this will not have been parsed, and can optionally be fed back into the parser.
• The ShortcodeParser instance used to parse the content.
• The shortcode tag name that was matched within the parsed content.
• An associative array of extra information about the shortcode being parsed. For example, if the shortcode is is inside an attribute, the element key contains a reference to the parent DOMElement, and the node key the attribute's DOMNode.

To register a shortcode you call the following.

// app/_config.php
use App\ShortCode\MyShortCodeProvider;

// ShortcodeParser::get('default')->register($shortcode, $callback);
ShortcodeParser::get('default')->register('my_shortcode', [MyShortCodeProvider::class, 'parseMyShortCode']);

Note that the callback can be any callable, including an anonymous function.

Built-in shortcodes#

Silverstripe CMS comes with several shortcode parsers already.

Links#

Internal page links keep references to their database IDs rather than the URL, in order to make these links resilient against moving the target page to a different location in the page tree. This is done through the [sitetree_link] shortcode, which takes an id parameter.

 <a href="[sitetree_link,id=99]">...</a>

Links to internal File database records work exactly the same, but with the [file_link] shortcode.

 <a href="[file_link,id=99]">...</a>

Images#

Images inserted through the "Insert Media" form (WYSIWYG editor) need to retain a relationship with the underlying Image database record. The [image] shortcode saves this database reference instead of hard-linking to the filesystem path of a given image.

[image id="99" alt="My text"]

Media (photo, video and rich content)#

Many media formats can be embedded into websites through the <object> tag, but some require plugins like Flash or special markup and attributes. OEmbed is a standard to discover these formats based on a simple URL, for example a Youtube link pasted into the "Insert Media" form of the CMS.

Since TinyMCE can't represent all these variations, we're showing a placeholder instead, and storing the URL with a custom [embed] shortcode.

[embed width=480 height=270 class=left thumbnail=http://i1.ytimg.com/vi/lmWeD-vZAMY/hqdefault.jpg?r=8767]
    http://www.youtube.com/watch?v=lmWeD-vZAMY
[/embed]

Attribute and element scope#

HTML with unprocessed shortcodes in it is still valid HTML. As a result, shortcodes can be in two places in HTML:

• In an attribute value, like so: <a title="[title]">link</a>
• In an element's text, like so: <p>Some text [shortcode] more text</p>

The first is called "element scope" use, the second "attribute scope"

You may not use shortcodes in any other location. Specifically, you can not use shortcodes to generate attributes or change the name of a tag. These usages are forbidden:

<[paragraph]>Some test</[paragraph]>

<a [titleattribute]>link</a>

You may need to escape text inside attributes > becomes >, You can include HTML tags inside a shortcode tag, but you need to be careful of nesting to ensure you don't break the output.

<!-- Good -->
<div>
    [shortcode]
        <p>Caption</p>
    [/shortcode]
</div>

<!-- Bad: -->

<div>
    [shortcode]
</div>
<p>
    [/shortcode]
</p>

Location#

Element scoped shortcodes have a special ability to move the location they are inserted at to comply with HTML lexical rules. Take for example this basic paragraph tag:

<p><a href="#">Head [figure,src="assets/a.jpg",caption="caption"] Tail</a></p>

When converted naively would become:

<p><a href="#">Head <figure><img src="assets/a.jpg" /><figcaption>caption</figcaption></figure> Tail</a></p>

However this is not valid HTML - P elements can not contain other block level elements.

To fix this you can specify a "location" attribute on a shortcode. When the location attribute is "left" or "right" the inserted content will be moved to immediately before the block tag. The result is this:

<figure><img src="assets/a.jpg" /><figcaption>caption</figcaption></figure><p><a href="#">Head  Tail</a></p>

When the location attribute is "leftAlone" or "center" then the DOM is split around the element. The result is this:

<p><a href="#">Head </a></p><figure><img src="assets/a.jpg" /><figcaption>caption</figcaption></figure><p><a href="#"> Tail</a></p>

Parameter values#

Here is a summary of the callback parameter values based on some example shortcodes.

namespace App\ShortCode;

use SilverStripe\View\Parsers\ShortcodeParser;

class MyShortCodeProvider
{
    public static function myCustomShortCode(
        array $arguments,
        ?string $content,
        ShortcodeParser $parser,
        string $tagName
    ) {
        // ...
    }
}

[my_shortcode]
$attributes     => [];
$content        => null;
$parser         => ShortcodeParser instance,
$tagName        => 'my_shortcode'

[my_shortcode,attribute="foo",other="bar"]
$attributes      => ['attribute'  => 'foo', 'other'      => 'bar']
$enclosedContent => null
$parser          => ShortcodeParser instance
$tagName         => 'my_shortcode'

[my_shortcode,attribute="foo"]content[/my_shortcode]
$attributes      => ['attribute' => 'foo']
$enclosedContent => 'content'
$parser          => ShortcodeParser instance
$tagName         => 'my_shortcode'

Limitations#

Since the shortcode parser is based on a simple regular expression it cannot properly handle nested shortcodes. For example the below code will not work as expected:

[shortcode]
[shortcode][/shortcode]
[/shortcode]

The parser will raise an error if it can not find a matching opening tag for any particular closing tag

Related documentation#

• Wordpress Implementation
• How to Create a Google Maps Shortcode

API documentation#

• ShortcodeParser