How to do math in a Django template?

Question

I want to do this:

100 - {{ object.article.rating_score }}  

So for example, the output would be 20 if {{ object.article.rating_score }} equaled 80.

How do I do this at the template level? I don't have access to the Python code.

Answer 1

You can use the add filter:

{{ object.article.rating_score|add:"-100" }} 

Answer 2

Use django-mathfilters. In addition to the built-in add filter, it provides filters to subtract, multiply, divide, and take the absolute value.

For the specific example above, you would use {{ 100|sub:object.article.rating_score }}.