subclassing sorl-thumbnail `ThumbnailBackend` class, and overriding _get_thumbnail_filename does not work

Question

I intend to subclass the ThumbnailBackend class from sorl.thumbnail.base. What I need to do is to override the _get_thumbnail_filename method, to add some stuff to the filename generated by the original (parent) method. To do so, I wrote something like this:

from sorl.thumbnail.base import ThumbnailBackend

class MyThumbnailBackend(ThumbnailBackend):
    def _get_thumbnail_filename(self, source, geometry_string, options):
        oldpath = super(ThumbnailBackend,self)._get_thumbnail_filename(source, geometry_string, options)
        oldpathlist = oldpath.split('/')
        # get the last item of 'oldpathlist' and
        # sufix it with useful info...
        # join the items with the modified one...
        return newpath

There should be something I'm missing with python inheritance, because I keep getting the following error:

AttributeError at /location/of/the/caller/class/
'super' object has no attribute '_get_thumbnail_filename'

If I'm right, I'm importing this class, in the first line: from sorl.thumbnail.base import ThumbnailBackend which definitely has a _get_thumbnail_filename method.

What am I doing wrong?

Thank you very much!

Answer 1

You have to call super with the current class, change super(ThumbnailBackend, self) to super(MyThumbnailBackend, self), like this

class MyThumbnailBackend(ThumbnailBackend):
    def _get_thumbnail_filename(self, source, geometry_string, options):
        return super(MyThumbnailBackend, self)._get_thumbnail_filename(source, geometry_string, options)