Question

I have a model which store generic foreign keys to different objects. I am displaying the list somewhere and due to space constraint I want to splice the object name.

So I am doing the following

{{list_object.content_object|slice:":20"}}

but this does not work. However when I do

{{list_object.content_object.title|slice:":20"}}

the slicing works. However I cannot use this, as content_object is a generic foreign key and every object ma not have an attribute named title.

Please help!

Answer 1

When you do slice directly on the object, Django never calls __unicode__, but rather passes the object directly into the filter. This is the actual behavior that should happen. When you do {{ some_object }} in your template, Django only auto-magically calls __unicode__ for you because it needs to print out something.

Your best bet would be to add a method to your model to provide a shortened name, and then use that method in your template:

def MyModel(models.Model):
    ...
    def get_short_content_title(self):
        return unicode(self.content_object)[:20]

And in your template:

{{ list_object.get_short_content_title }}

Or technically you could merely proxy the __unicode__ call and handle it in the template however you want:

def MyModel(models.Model):
    def get_content_title(self):
        return unicode(self.content_object)

And in your template:

{{ list_object.get_content_title|slice:":20" }}

Whichever works best in your scenario.

Actually one more alternative would be to create a simple template filter to return the unicode value of an object:

@register.filter
def get_unicode(obj):
    return unicode(obj)

Then, in your template:

 {{ list_object.content_object|get_unicode|slice:":20" }}

Don’t you love options? 😉