Django admin and showing thumbnail images

This is in the source for photologue (see models.py, slightly adapted to remove irrelevant stuff):

def admin_thumbnail(self):
    return u'<img src="%s" />' % (self.image.url)
admin_thumbnail.short_description = 'Thumbnail'
admin_thumbnail.allow_tags = True

The list_display bit looks identical too, and I know that works. The only thing that looks suspect to me is your indentation - the two lines beginning image_img at the end of your models.py code should be level with def image_img(self):, like this:

def image_img(self):
    if self.image:
        return u'<img src="%s" />' % self.image.url_125x125
    else:
        return '(Sin imagen)'
image_img.short_description = 'Thumb'
image_img.allow_tags = True

Update v. 1.9

Note that in Django v.1.9

image_tag.allow_tags = True

is depricated and you should use format_html(), format_html_join(), or mark_safe() instead

So your model.py should look like this:

...
def image_img(self):
    if self.image:
        return marksafe('<img src="%s" />' % self.image.url_125x125)
    else:
        return '(Sin imagen)'
    image_img.short_description = 'Thumb'

and in your admin.py add:

list_display= ('image_img','product',)
readonly_fields = ('image_img',)

and for adding it in the 'Edit mode' of your admin panel in your admin.py add:

fields = ( 'image_img', )

Add a method in your model (models.py):

def image_tag(self):
    return u'<img src="%s" />' % <URL to the image>
image_tag.short_description = 'Image'
image_tag.allow_tags = True

and in your ModelAdmin (admin.py) add:

readonly_fields = ('image_tag',)