Most importantly, the problem exists only with the0.96x version of Django. If you are up to date with trunk, you can skip this article.

The issues are as follows:
- the textile markup.py code in Django 0.96x assumes that input to textile is in the Django default encoding, which usually is utf-8
- Django database typically uses utf-8 encoding for storage, but
- Python2.5 + Django 0.96x is mostly unicode

Considering the following sources of data for used by the “textile” filter in a template, only the last case, using clean_data, will break:

1. Direct objects retrieved from database, works fine.
2. Browser input via GET, works fine
3. Browser input via form POST, accessed not using clean_data, works fine
4. The clean_data pseudo dictionary returns data in unicode, and will break the textile filter.

Code Example:
# view:
obj = ModelClass.objects.get(pk=id)
# template:
{{ obj.textile }} works

# view:
field = request.GET.get(‘some_field’)
# template:
{{ field | textile }} works

# view:
field = request.POST.get(‘some_field’)
# template:
{{ field | textile }} works

# view:
form = TestForm(request.POST)
field = form.clean_data['some_field']
# template:
{{ field | textile }} gives:

Exception Type: UnicodeDecodeError
Exception Value: ‘ascii’ codec can’t decode byte 0xb4 in position 0: ordinal not in range(128)

Implication
A very common pattern for object editing is to let the user input data for a field, saves it to the database, and finish with a template displaying the updated data. Unfortunately, since the database object is updated with the form.clean_data input, it will break on the display template after saving to the database.

Solution
There are two possible solutions. The first one that I proposed earlier is for force the data encoding to utf-8 when assigning a model field from clean_data. e.g.:

my_object.field = clean_data['field_name'].encode(‘utf-8′)

A better solution, is to encapsulate the textile processing in a function. Do not force the template author even know that we are using textile. Before Django 1.0, this function will do the magic utf-8 conversion. At Django 1.0, the function can simply call pytextile.

class MyClass(models.Model):
    body = models.CharField()

    def body_formatted(self):
        import textile
        return textile.textile( self.body.encode('utf-8'),
                encoding='utf-8', output='utf-8')