Preview is a lightweight template engine class that extends the View class.

Namespace: \
File location: lib/base.php

Render a Preview Template

The Preview Template class offers a mechanism for extremely lightweight templating that just calls some php expressions which are wrapped into the {~ ~} control chars. This is useful for any kind of template style, like XML/HTML, haml, or anything else.

Lets have a look at a simple example:

	<h1>My favorite books</h1>
		{~ foreach (@books as @id=>@book): ~}
		<li>{~ if (@book.starred): ~}<i class="icon-star"></i>{~ else: ~}<i class="icon-normal">{~ endif ~}
			<a href="{{ @BASE.@book[slug] }}">{{ @book.title }}</a>
		{~ endforeach ~}



Assemble markup

string build ( string $node )

This method builds the php code out of the given markup, that is used later in the pre-rendered template. To know about this method becomes useful when you're creating new template extensions or custom tag handlers.

In example it converts this piece of token:

{{ @book.title | esc }}


<?php echo $this->esc($book['title']); ?>


Register token filter

mixed filter ( [ string $key = NULL [, string $func = NULL ] )

You can use this method to add your own template token filter like {{ @content | myfilter }}. For instance:

class Helper extends \Prefab {
	function badwords($val) {
		$bad_words = array("badword","jerk","damn");
		$replacement_words = array("@#$@#", "j&*%", "da*@"); 
		return str_ireplace($bad_words, $replacement_words, $val);

Now you can use {{ @user_comment | badwords }} to filter the user_comment var for badwords. It's also possible to combine multiple filter: {{ @user_comment | badwords, raw }}.

When the function is called without any parameter, it just returns an array of all registered filter names. When the function is called with a $key but without a $func parameter, it returns the registered function string.


Render and return a template given by its filename

string render ( string $file [, string $mime = 'text/html' [, array $hive = NULL [, int $ttl = 0 ]]] )

The $file argument expects a file path that is within any defined directories by F3's UI system variables. Remember, for your convenience, UI can be multiple paths.

Actually, the render method first try to load your specified template from the temporary folder TEMP acting as a file cache for compiled templates. The specified template file is only load if needed: F3 is smart enough to detect if a newer version of the template file has been saved and then it builds a php based view file and only then renders the php view again.

Once rendered, F3 escape the content according to the ESCAPE system variable, and sets the appropriate Content-Type: value of the HTTP header. If you'd like to get the response returned as JSON, XML or as E-Mail content, just change the $mime type parameter accordingly to your needs. (While the charset of the content is defined by the ENCODING system variable)

The $hive argument allows you to use an explicit array of variables for that template. By default the rendered template has access to the whole F3 hive with all it's variables.

The $ttl argument specifies, in seconds, the Time To Live in the F3 cache for the php based compiled view file. When a $ttl is given, F3 will store the compiled view in the cache. On the next request, if the time specified by $ttl has passed, the compiled view will be rebuild from the template and stored again in the cache for another cycle.


echo $tmpl->render('layout.html'); // assumes layout.html is in the UI folder
$flow = $tmpl->render('widgets/tweeter-feeds.html', 'application/json', NULL, 300 ); // cache for 5 minutes


Render template string

string resolve ( string $str [, array $hive = NULL ] )


$tmpl = \Preview::instance();
$f3->set('title','<b>F3 rocks</b>');
$content = '<p>{{ @title | esc }}</p>';
echo $tmpl->resolve($content);
// return: <p>&amp;lt;b&amp;gt;F3 rocks&lt;/b&amp;gt;</p>


Convert token to variable

string token ( string $str )


echo $template->token ('My {{@color}} car looks nice');

// returns the string  'My $color car looks nice'