[Answer]-Override django-taggit tags so that they are always lowercase

I usually implement this at the form level:

def clean_tags(self):
    """
    Force all tags to lowercase.
    """
    tags = self.cleaned_data.get('tags', None)
    if tags:
        tags = [t.lower() for t in tags]

    return tags

It really depends on how you look at it. I’m happy with solution because I consider it a validation problem. If you consider it a data integrity problem, I can understand why you’d want to do it at the model level. At which point your best bet is to subclass the taggit modules to a point that you can override Tag.save().

In the appname –> utils file, for eg:(blog –> init.py), define a function as follows:

def comma_splitter(tag_string):
"""convert each tag into lowercase"""
return [t.strip().lower() for t in tag_string.split(‘,’) if t.strip()]

And then, in the settings.py file, define and override the default taggit settings as:
TAGGIT_TAGS_FROM_STRING = ‘blog.init.comma_splitter’