Calling Python function in Django template

Question

Inside a django template I'm trying to call the split function on one of the template variables and then get the last element, so I did something like this:

{{ newsletter.NewsletterPath.split('/').-1 }}

Unfortunately, it doesn't like the split. Some might suggest that I do the split in the view, but I'm not sure how to do that because I need to do it for all of the records. It would be much easier if I could do it in the template. Is there a way to do this?

Answer 1

From the django book:

Note that you do not include parentheses in the method calls. Also, it’s not possible to pass arguments to the methods; you can only call methods that have no required arguments.

So, if you want to call a method without arguments from a template, it's ok. Else, you have to do it in the view.

Answer 2

Templates are deliberately not able to do such stuff. The purpose is to prevent you from putting your business logic in templates, which are meant to deal only with the layout.

So a possible way to do this is to define a NewsletterPathLastElement(self) function in your newsletter Model, and call that from the template.

Answer 3

What do you mean by "it doesn't like the split"? How does it manifest its dislike?

If I remember correctly, you can not pass any arbitrary arguments to methods, that are called from the django template and the identifiers, that can be used in the templates can only consist of a-z, A-Z, 0-9, underscores and dots (where dots signify lookup: dictionary->attribute->method->list-index).

There are at least four ways to achieve what you want:

• make the appropriately prepared data available as an attribute of your model (or whatever that is), by pre-processing it
• make the data available as a method of your model and make sure, that the method takes no required arguments, besides self

• populate the model instances in the view

   for newsletter in newsletters:
        setattr(newsletter, 'basepath',
                newsletter.NewsletterPath.split('/')[-1])
  

  (or something along these lines)

• implement a custom filter tag, that will handle the split (easier, than you might think)

Answer 4

Yes, as others have said, you shouldn't really be doing it in the templates.

But if you want to, then you need to define a filter and load it in the template and use it.