Is it possible to set query parameters via jinja in Pelican template files?

`index.html`

```
{% if articles %}
    {% for article in articles_page.object_list if article.category == 'article' %}        
        #stuff
    {% endfor %}
{% endif %}

```

This will return articles in the article category, but only if they happen to be in the articles already queried for. The desirable setup would be to grab x articles in y category (or with y tag) - is that possible?