Creating an RSS builder in ExpressionEngine

A recent project called for the ability to dynamically create RSS feeds based on user-selectable categories. ExpressionEngine lets you use the ‘category’ keyword to zero in on a particular category (or categories) when creating an RSS feed. In this project we wanted the end user to be able to select from a number of categories to create a custom RSS feed.

Note: This is a simple solution and not particularly beautiful but works well enough (except for Safari). Spaces inserted into the code block below to allow for proper display.

Demo page: http://www.smd.net.au/site/rssbuilder

There are two templates. The first calls up our categories for a particular weblog – in this case it’s our Journal section.

 <h2>Journal entries:</h2>
 <form action="{path="site/rssbuilder_result/"}" method="get" accept-charset="utf-8">
 {exp:weblog:categories weblog="journal" style="linear" dynamic="off" category_group="2" category="not 18"}
 <input type="checkbox" name="cat" value="{category_id}" />{category_name}<br/>
 {/exp:weblog:categories}
 <p><input type="reset" value="Reset!"><input type="submit" value="Submit"></p>
 </form>  

The second template is where our results get pushed. This is where the ugly stuff happens. (Explanation is below the code).

 < h1 >RSS Builder Results</ h1 >
 < ?php
 function curPageURL() {
 $pageURL = 'http';
 $pageURL .= "://";
 if ($_SERVER["SERVER_PORT"] != "80") {
 $pageURL .= $_SERVER["SERVER_NAME"].":".$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"];
 } else {
 $pageURL .= $_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"];
 }
 return $pageURL;
 }
 ? >
 <p>Click below for your custom RSS feed:</p>
 {exp:replace find="http://www.smd.net.au/site/rssbuilder_result/|?cat=|&cat=" replace="http://www.smd.net.au/site/journal_rss/|category/|&#124;" multiple="yes"}
 <p><a href="&lt;?php echo curPageURL();?&gt;">&lt;?php echo curPageURL();?&gt;</a>
 {/exp:replace}

The block of PHP gets the current URL from the browser and is echoed with:

 < ?php echo curPageURL();? >

This is wrapped up in the only third-party plugin you’ll need here, Lodewijk Schutte’s Find & Replace.

This takes the browser URL and replaces it with our RSS url and adds the category keyword. Anything with “?cat” and “&cat;” it replaces with the “|” piping character. Because this is the character used in the plugin we need to use the unicode version of |.

So now our link goes from looking like this:

  http ://www.smd.net.au/site/rssbuilder_result/?cat=7&cat=10

to this link which can be copied into an RSS reader:

  http ://www.smd.net.au/site/journal_rss/category/7|10