sorl-thumbnail doesn't generate placeholder images

Question

I'm trying to upgrade a django project using the old sorl-thumbnail (v.3.2.5) to the newest (v.12.0) but I'm not able to get it generate placeholder images in development environment using the settings provided: http://sorl-thumbnail.readthedocs.org/en/latest/reference/settings.html#thumbnail-dummy

Here are my settings:

THUMBNAIL_DEBUG = True
THUMBNAIL_DUMMY = True
THUMBNAIL_DUMMY_SOURCE = 'http://placekitten.com/%(width)s/%(height)s'
MEDIA_URL = '/media/'

CACHES = {                                                                                   
    'default': {
        'BACKEND': 'django.core.cache.backends.memcached.MemcachedCache',
        'LOCATION': '127.0.0.1:11211',
    }
}

This is the model using sorl ImageField:

from sorl.thumbnail import ImageField

class Cover(models.Model):
    [... other fields here]
    image = ImageField("immagine", upload_to='images/cover/%Y/%m/%d', max_length=255)

and the admin inherits from sorl.thumbnail.admin.AdminImageMixin. The project uses Django 1.6 but I tried same settings on another project which uses Django 1.5.5 and I have the same problem.

Thumbnails are correctly generated (and retrieved from cache) for newly updated images, but pre-existent images are not substituted with placeholders, neither in admin nor in frontend pages (development server answers with a 404).

Any clues? Sorl docs are really scarce...

Answer 1

After searching through sorl-thumbnail code I found out that in the admin the THUMBNAIL_DUMMY setting is not even considered... There is a pull request to solve this (opened a year ago): https://github.com/mariocesar/sorl-thumbnail/pull/128

As for the frontend it works, it was just a silly mistake in the template.