How to use boolean negation in "where:"?

Question

I am trying to write a query to retrieve posts of all categories but the category "Personal".

I have the following code to retrieve all posts which are tagged as "Personal", so I tried to use " ! " and " not " to get which are not "Personal".

{% assign sorted-posts = site.posts | where: "categories", "Personal" %}
  ...
{% endfor %}

So, I tried this:

{% assign sorted-posts = site.posts | not where: "categories", "Personal" %}
  ...
{% endfor %}

and

{% assign sorted-posts = site.posts | ! where: "categories", "Personal" %}
  ...
{% endfor %}

It didn't work. How can I use " not " or " ! " in Liquid?

Answer 1

As post.categories is an array, you can check if it contains a certain value with contains filter. eg : if post.categories contains "Personal"

The unless control flow tag, which is equivalent to "if not" can now be used to print all posts that are not from "personal" category.

<ul>
{% for post in site.posts %}
  {% unless post.categories contains "Personal" %}
    <li><a href="{{ site.baseurl }}{{ post.url }}">{{ post.title }}</a></li>
  {% endunless %}
{% endfor %}
</ul>