Check to see if category is populated?

Question

I want to list all categories that have an entry assigned to them, but hide the ones that are empty.

In EE I could do this show_empty="no"

But I can't see a parameter in the docs for Craft.

Currently I've found that I could use relatedTo but with passing an object with up to 600 entries it dies with caching tags :(

Is there a better way of doing this? This is what I've got at the moment:

{% set blogPosts = craft.entries({section:'blog',limit:null}).find() %}

{% for cat in craft.categories({groupId:2}).relatedTo(blogPosts) %}
   <li><a href="/blog/{{cat.slug}}">{{cat.title}}</a> </li>
{% endfor %}

Answer 1

There is a great tutorial over at Straight Up Craft for handling this (it is however very similar to what you have - it may speed things up a tad though).

First, we want to grab all of the entry ids from the Section of content which we want to display categories for.

{% set entryIds = craft.entries.section('blog').ids() %}

Next, we will use the craft.categories tags relatedTo() method to only return categories that have a relationship with one of our entry ids.

{% set categories = craft.categories.relatedTo({ sourceElement: entryIds }).groupId(1).find() %}

Once we have our list of categories that are in use, we can loop through those categories and display them in our template:

{% for category in categories %}
    <li><a href="{{ category.url }}">{{ category.title }}</a></li>
{% endfor %}