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https://github.com/silverstripe/silverstripe-framework
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Original example gives: Fatal error: Using $this when not in object context in E:\localhost\abscreensavers.com\mysite\code\Page.php on line 19
225 lines
7.3 KiB
Markdown
225 lines
7.3 KiB
Markdown
title: Shortcodes
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summary: Flexible content embedding
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# Shortcodes
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The [api:ShortcodeParser] API is simple parser that allows you to map specifically formatted content to a callback to
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transform them into something else. You might know this concept from forum software which don't allow you to insert
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direct HTML, instead resorting to a custom syntax.
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In the CMS, authors often want to insert content elements which go beyond standard formatting, at an arbitrary position
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in their WYSIWYG editor. Shortcodes are a semi-technical solution for this. A good example would be embedding a 3D file
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viewer or a Google Map at a certain location.
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:::php
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$text = "<h1>My Map</h1>[map]"
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// Will output
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// <h1>My Map</h1><iframe ..></iframe>
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Here's some syntax variations:
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:::php
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[my_shortcode]
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#
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[my_shortcode /]
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#
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[my_shortcode,myparameter="value"]
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#
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[my_shortcode,myparameter="value"]Enclosed Content[/my_shortcode]
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Shortcodes are automatically parsed on any database field which is declared as [api:HTMLValue] or [api:HTMLText],
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when rendered into a template. This means you can use shortcodes on common fields like `SiteTree.Content`, and any
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other `[api:DataObject::$db]` definitions of these types.
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Other fields can be manually parsed with shortcodes through the `parse` method.
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:::php
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$text = "My awesome [my_shortcode] is here.";
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ShortcodeParser::get_active()->parse($text);
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## Defining Custom Shortcodes
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First we need to define a callback for the shortcode.
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**mysite/code/Page.php**
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:::php
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<?php
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class Page extends SiteTree {
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private static $casting = array(
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'MyShortCodeMethod' => 'HTMLText'
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);
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public function MyShortCodeMethod($arguments, $content = null, $parser = null, $tagName) {
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return "<em>" . $tagName . "</em> " . $content . "; " . count($arguments) . " arguments.";
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}
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}
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These parameters are passed to the `MyShortCodeMethod` callback:
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- Any parameters attached to the shortcode as an associative array (keys are lower-case).
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- Any content enclosed within the shortcode (if it is an enclosing shortcode). Note that any content within this
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will not have been parsed, and can optionally be fed back into the parser.
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- The ShortcodeParser instance used to parse the content.
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- The shortcode tag name that was matched within the parsed content.
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- An associative array of extra information about the shortcode being parsed. For example, if the shortcode is
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is inside an attribute, the `element` key contains a reference to the parent `DOMElement`, and the `node`
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key the attribute's `DOMNode`.
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To register a shortcode you call the following.
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**mysite/_config.php**
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:::php
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// ShortcodeParser::get('default')->register($shortcode, $callback);
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ShortcodeParser::get('default')->register('my_shortcode', array('Page', 'MyShortCodeMethod'));
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## Built-in Shortcodes
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SilverStripe comes with several shortcode parsers already.
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### Links
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Internal page links keep references to their database IDs rather than the URL, in order to make these links resilient
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against moving the target page to a different location in the page tree. This is done through the `[sitetree_link]`
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shortcode, which takes an `id` parameter.
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:::php
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<a href="[sitetree_link,id=99]">
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Links to internal `File` database records work exactly the same, but with the `[file_link]` shortcode.
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:::php
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<a href="[file_link,id=99]">
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### Media (Photo, Video and Rich Content)
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Many media formats can be embedded into websites through the `<object>` tag, but some require plugins like Flash or
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special markup and attributes. OEmbed is a standard to discover these formats based on a simple URL, for example a
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Youtube link pasted into the "Insert Media" form of the CMS.
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Since TinyMCE can't represent all these variations, we're showing a placeholder instead, and storing the URL with a
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custom `[embed]` shortcode.
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[embed width=480 height=270 class=left thumbnail=http://i1.ytimg.com/vi/lmWeD-vZAMY/hqdefault.jpg?r=8767]
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http://www.youtube.com/watch?v=lmWeD-vZAMY
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[/embed]
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### Attribute and element scope
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HTML with unprocessed shortcodes in it is still valid HTML. As a result, shortcodes can be in two places in HTML:
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- In an attribute value, like so: `<a title="[title]">link</a>`
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- In an element's text, like so: `<p>Some text [shortcode] more text</p>`
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The first is called "element scope" use, the second "attribute scope"
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You may not use shortcodes in any other location. Specifically, you can not use shortcodes to generate attributes or
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change the name of a tag. These usages are forbidden:
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<[paragraph]>Some test</[paragraph]>
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<a [titleattribute]>link</a>
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You may need to escape text inside attributes `>` becomes `>`, You can include HTML tags inside a shortcode tag, but
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you need to be careful of nesting to ensure you don't break the output.
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:::ss
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<!-- Good -->
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<div>
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[shortcode]
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<p>Caption</p>
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[/shortcode]
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</div>
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<!-- Bad: -->
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<div>
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[shortcode]
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</div>
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<p>
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[/shortcode]
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</p>
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### Location
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Element scoped shortcodes have a special ability to move the location they are inserted at to comply with HTML lexical
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rules. Take for example this basic paragraph tag:
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<p><a href="#">Head [figure,src="assets/a.jpg",caption="caption"] Tail</a></p>
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When converted naively would become:
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<p><a href="#">Head <figure><img src="assets/a.jpg" /><figcaption>caption</figcaption></figure> Tail</a></p>
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However this is not valid HTML - P elements can not contain other block level elements.
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To fix this you can specify a "location" attribute on a shortcode. When the location attribute is "left" or "right"
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the inserted content will be moved to immediately before the block tag. The result is this:
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<figure><img src="assets/a.jpg" /><figcaption>caption</figcaption></figure><p><a href="#">Head Tail</a></p>
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When the location attribute is "leftAlone" or "center" then the DOM is split around the element. The result is this:
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<p><a href="#">Head </a></p><figure><img src="assets/a.jpg" /><figcaption>caption</figcaption></figure><p><a href="#"> Tail</a></p>
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### Parameter values
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Here is a summary of the callback parameter values based on some example shortcodes.
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:::php
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public function MyCustomShortCode($arguments, $content = null, $parser = null, $tagName) {
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// ..
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}
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[my_shortcode]
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$attributes => array();
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$content => null;
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$parser => ShortcodeParser instance,
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$tagName => 'myshortcode')
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[my_shortcode,attribute="foo",other="bar"]
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$attributes => array ('attribute' => 'foo', 'other' => 'bar')
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$enclosedContent => null
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$parser => ShortcodeParser instance
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$tagName => 'my_shortcode'
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[my_shortcode,attribute="foo"]content[/my_shortcode]
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$attributes => array('attribute' => 'foo')
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$enclosedContent => 'content'
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$parser => ShortcodeParser instance
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$tagName => 'my_shortcode'
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## Limitations
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Since the shortcode parser is based on a simple regular expression it cannot properly handle nested shortcodes. For
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example the below code will not work as expected:
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[shortcode]
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[shortcode][/shortcode]
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[/shortcode]
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The parser will raise an error if it can not find a matching opening tag for any particular closing tag
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## Related Documentation
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* [Wordpress Implementation](http://codex.wordpress.org/Shortcode_API)
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* [How to Create a Google Maps Shortcode](how_tos/create_a_google_maps_shortcode)
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## API Documentation
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* [api:ShortcodeParser]
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