Requirement 1

The first requirement - displaying multiple categories - is quite easy to achieve. Remember that we can add a “category” attribute to any {exp:weblog:entries} tag to control which categories should be displayed. Use category="2" to just display all weblog entries associated with category 2 - use category="2|4|6" to display entries that are associated with category 2, 4 or 6. You can also exclude category by just placing a “not” in front of the respective id. Simple huh?

Requirement 2

The second requirement is a bit more tricky. Remember, I wanted to dynamically alter the set of categories displayed. In a first step I played with the thought to use the search module - but that didn’t work. It’s easier to dynamically insert the respective values using PHP. I know it’s not recommended to make use of PHP in your templates due to security issues. In my case however I thought it’s acceptable. So here we go:

Solution

Those of you familiar with EE might know that you can display entries of a certain category by adding “C” plus the respective ID to the URL: e.g. …/journal/categories/C2. In this case EE would display all entries filed under category 2.

My approach was to define multiple categories “…/journal/categories/C2&C4&C6”, parse the query string via PHP, replace all “&” with “|”, assign the generated value to the variable “$query” and pass its value to the category attribute:

{exp:weblog:entries weblog="{my_weblog}" category="<?php echo $query;?>" dynamic="off"}.