Creating custom template tags and filters

Django offers a variety of built-in template tags, such as {% if %} or {% block %}. You used different template tags in Chapter 1, Building a Blog Application, and Chapter 2, Enhancing Your Blog with Advanced Features. You can find a complete reference of built-in template tags and filters at https://docs.djangoproject.com/en/5.0/ref/templates/builtins/.

Django also allows you to create your own template tags to perform custom actions. Custom template tags come in very handy when you need to add a functionality to your templates that is not covered by the core set of Django template tags. This can be a tag to execute a QuerySet or any server-side processing that you want to reuse across templates. For example, we could build a template tag to display the list of latest posts published on the blog. We could include this list in the sidebar, so that it is always visible, regardless...