When using a callable in the list_display, as in the cases of initialled_name and isbn13, we can use the admin.display decorator to specify the column name that will appear in the header of the change list using the description argument. We can also use it to get around the limitation of calculated fields not being sortable by specifying ordering on the callable. The empty_value argument can be used to specify how a None value or empty string is displayed. The default empty_value display is a single dash character:

@admin.display(ordering='isbn', description='ISBN-13', empty_value='-/-')
def isbn13(self, obj):
    """ '9780316769174' => '978-0-31-676917-4' """
    return "{}-{}-{}-{}-{}".format(obj.isbn[0:3], obj.isbn[3:4], obj.isbn[4:6], obj.isbn[6:12], obj.isbn[12:13])

The boolean argument to admin.display can be used to flag a value to be represented in Boolean form:

@admin.display(boolean=True, description='Has ISBN')
def has_isbn(self, obj):
    """ '9780316769174' => True """
    return bool(obj.isbn)

Together these display decorator settings will give us display columns that look like this:

Source

Web development with Django, Ben Shaw, Saurabh Badhwar, Chris Guest, Bharath Chandra K S