Displaying PDFs in django; decoding error - django

Question

I'm trying to pass a PDF into a Django app and am running into an issue with unicode/decoding the PDF. The PDFs are being stored in a mysql database, in a mediumblob field. I'd appreciate any help on this, as it seems the encoding is running into a problem with the metadata of the PDF, and I'm not sure where to go with this - I've checked out several questions that seem similar but can't find what I'm looking for. Do I need to decode/recode the PDFs somehow? Thanks!
Here is the error:
Request Method: POST
Request URL: http://0.0.0.0:8000/admin/pdf/abc/
Exception Type: DjangoUnicodeDecodeError
Exception Value: 'utf8' codec can't decode byte 0x89 in position 614: unexpected code byte
Exception Location: /usr/lib/python2.5/site-packages/django/utils/encoding.py in force_unicode, line 92
Python Executable: /usr/bin/python
My code is below:
class ABCAdmin(admin.ModelAdmin):
actions = ['print_selected_pdf']
def get_user(self):
return '%s'%(self.user.username)
def create_pdf(self, queryset):
response = HttpResponse(mimetype="applicaton/pdf")
response['Content-Disposition'] = 'attachment; filename=form.pdf'
p=canvas.Canvas(response)
# loop through the objects
for obj in queryset:
string1 = (obj.form)
# update the label_printed to true
obj.pdf_printed=True
obj.save()
p.save()
return response
def print_selected_pdf(self, request, queryset):
# prints the pdfs for those that are selected,
# regardless if the pdf_printed field is true or false
return self.create_pdf(queryset.order_by('user'))
print_selected_pdf.short_description = "Print selected PDF"
get_user.short_description='Printed By'
list_display=('form_no',get_user,'request_date','pdf_printed')
def queryset(self,request):
# get the user id
user = User.objects.get(username=request.user)
if request.user.is_superuser:
qs = self.model._default_manager.all()
else:
qs = self.model._default_manager.filter(user=user.id)
return qs
def formfield_for_foreignkey(self, db_field, request, **kwargs):
if db_field.name == "user" and not request.user.is_superuser:
# get the user id
user = User.objects.get(username=request.user)
kwargs["queryset"]=User.objects.filter(id=user.id)
return db_field.formfield(**kwargs)
return super(ABCAdmin,self).formfield_for_foreignkey(
db_field, request, **kwargs)
admin.site.register(ABC, ABCAdmin)
Edit: Full trackback:
Environment:
Request Method: POST
Request URL: http://0.0.0.0:8000/admin/pdf/abc/
Django Version: 1.1
Python Version: 2.5.2
Installed Applications:
['django.contrib.auth',
'django.contrib.contenttypes',
'django.contrib.sessions',
'django.contrib.sites',
'django.contrib.admin',
'app.pdf']
Installed Middleware:
('django.middleware.common.CommonMiddleware',
'django.contrib.sessions.middleware.SessionMiddleware',
'django.contrib.auth.middleware.AuthenticationMiddleware')
Traceback:
File "/usr/lib/python2.5/site-packages/django/core/handlers/base.py" in get_response
92. response = callback(request, *callback_args, **callback_kwargs)
File "/usr/lib/python2.5/site-packages/django/contrib/admin/options.py" in wrapper
226. return self.admin_site.admin_view(view)(*args, **kwargs)
File "/usr/lib/python2.5/site-packages/django/views/decorators/cache.py" in _wrapped_view_func
44. response = view_func(request, *args, **kwargs)
File "/usr/lib/python2.5/site-packages/django/contrib/admin/sites.py" in inner
186. return view(request, *args, **kwargs)
File "/usr/lib/python2.5/site-packages/django/contrib/admin/options.py" in changelist_view
912. response = self.response_action(request,queryset=cl.get_query_set())
File "/usr/lib/python2.5/site-packages/django/contrib/admin/options.py" in response_action
694. response = func(self, request, queryset.filter(pk__in=selected))
File ".../pdf/admin.py" in print_selected_pdf
56. return self.create_pdf(queryset.order_by('user'))
File ".../pdf/admin.py" in create_pdf
48. obj.save()
File "/usr/lib/python2.5/site-packages/django/db/models/base.py" in save
410. self.save_base(force_insert=force_insert, force_update=force_update)
File "/usr/lib/python2.5/site-packages/django/db/models/base.py" in save_base
474. rows = manager.filter(pk=pk_val)._update(values)
File "/usr/lib/python2.5/site-packages/django/db/models/query.py" in _update
444. return query.execute_sql(None)
File "/usr/lib/python2.5/site-packages/django/db/models/sql/subqueries.py" in execute_sql
120. cursor = super(UpdateQuery, self).execute_sql(result_type)
File "/usr/lib/python2.5/site-packages/django/db/models/sql/query.py" in execute_sql
2369. cursor.execute(sql, params)
File "/usr/lib/python2.5/site-packages/django/db/backends/util.py" in execute
22. sql = self.db.ops.last_executed_query(self.cursor, sql, params)
File "/usr/lib/python2.5/site-packages/django/db/backends/__init__.py" in last_executed_query
213. u_params = tuple([to_unicode(val) for val in params])
File "/usr/lib/python2.5/site-packages/django/db/backends/__init__.py" in <lambda>
211. to_unicode = lambda s: force_unicode(s, strings_only=True)
File "/usr/lib/python2.5/site-packages/django/utils/encoding.py" in force_unicode
92. raise DjangoUnicodeDecodeError(s, *e.args)
Exception Type: DjangoUnicodeDecodeError at /admin/pdf/abc/
Exception Value: 'utf8' codec can't decode byte 0x89 in position 614: unexpected code byte. You passed in [redacted for length - here it displayed all of the metadata in the PDF]

Answer 1

The PDFs are being stored in a mysql database, in a mediumblob field.
You just lost the game. Use a FileField instead.

Answer 2

I had to use a queryset to avoid the decoding error. Filefield is not practical in my situation.