Django unicode issue with datetime in Jython with SQLite JDBC

Question

I recently started a Django project using Jython. I created a virtualenv and successfully created a Django 1.8.6 project, using a JDBC file for SQLite (sqlite-jdbc-3.8.11.2).

I could create a superuser with jython manage.py createsuperuser, loaded the admin URL and logged in successfully. I even could create another user from the admin. The problems begin when I tried to edit a user. The server cannot render the template of the detailed instance of the user Model.

I have not installed any external apps, nor created an app in the project. I am using django.contrib.auth for the User models and the Django admin default interface.

The initial error I get when I load the /admin/auth/user/1/ is 'unicode' object has no attribute 'tzinfo':

AttributeError at /admin/auth/user/1/

'unicode' object has no attribute 'tzinfo'

Request Method: GET
Request URL: http://localhost:8000/admin/auth/user/1/
Django Version: 1.8.6
Exception Type: AttributeError
Exception Value:

'unicode' object has no attribute 'tzinfo'

Exception Location: /home/dmunoz/jsnmp/Lib/site-packages/django/utils/timezone.py in is_aware, line 337
Python Executable: /home/dmunoz/jsnmp/bin/jython
Python Version: 2.7.0
Python Path:

['/home/dmunoz/snmp/webswitcher',
 '/home/dmunoz/jsnmp/Lib/site-packages/django_jython-1.8.0b3-py2.7.egg',
 '/home/dmunoz/jsnmp/Lib/site-packages',
 '/home/dmunoz/jsnmp/Lib',
 '/home/dmunoz/opt/jython2.7.0/Lib',
 '__classpath__',
 '__pyclasspath__/']

Server time: Tue, 10 Nov 2015 12:31:09 -0300

Error during template rendering

In template /home/dmunoz/jsnmp/Lib/site-packages/django/contrib/admin/templates/admin/includes/fieldset.html, error at line 19

Because of this, I tried setting USE_TZ = False in the settings.py file. Then, I got 'unicode' object has no attribute 'date':

AttributeError at /admin/auth/user/1/

'unicode' object has no attribute 'date'

Request Method: GET
Request URL: http://localhost:8000/admin/auth/user/1/
Django Version: 1.8.6
Exception Type: AttributeError
Exception Value:

'unicode' object has no attribute 'date'

Exception Location: /home/dmunoz/jsnmp/Lib/site-packages/django/forms/widgets.py in decompress, line 888
Python Executable: /home/dmunoz/jsnmp/bin/jython
Python Version: 2.7.0
Python Path:

['/home/dmunoz/snmp/webswitcher',
 '/home/dmunoz/jsnmp/Lib/site-packages/django_jython-1.8.0b3-py2.7.egg',
 '/home/dmunoz/jsnmp/Lib/site-packages',
 '/home/dmunoz/jsnmp/Lib',
 '/home/dmunoz/opt/jython2.7.0/Lib',
 '__classpath__',
 '__pyclasspath__/']

Server time: Tue, 10 Nov 2015 12:28:18 -0300

Error during template rendering

In template /home/dmunoz/jsnmp/Lib/site-packages/django/contrib/admin/templates/admin/includes/fieldset.html, error at line 19

The final error I have got is when I tried to dump the data from auth.User model with jython manage.py dumpdata auth.User --indent=4 --traceback:

[Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/dmunoz/jsnmp/Lib/site-packages/django/core/management/__init__.py", line 354, in execute_from_command_line
    utility.execute()
  File "/home/dmunoz/jsnmp/Lib/site-packages/django/core/management/__init__.py", line 346, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/dmunoz/jsnmp/Lib/site-packages/django/core/management/base.py", line 394, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/dmunoz/jsnmp/Lib/site-packages/django/core/management/base.py", line 445, in execute
    output = self.handle(*args, **options)
  File "/home/dmunoz/jsnmp/Lib/site-packages/django/core/management/commands/dumpdata.py", line 159, in handle
    serializers.serialize(format, get_objects(), indent=indent,
  File "/home/dmunoz/jsnmp/Lib/site-packages/django/core/serializers/__init__.py", line 129, in serialize
    s.serialize(queryset, **options)
  File "/home/dmunoz/jsnmp/Lib/site-packages/django/core/serializers/base.py", line 61, in serialize
    self.handle_field(obj, field)
  File "/home/dmunoz/jsnmp/Lib/site-packages/django/core/serializers/python.py", line 55, in handle_field
    self._current[field.name] = field.value_to_string(obj)
  File "/home/dmunoz/jsnmp/Lib/site-packages/django/db/models/fields/__init__.py", line 1487, in value_to_string
    return '' if val is None else val.isoformat()
AttributeError: 'unicode' object has no attribute 'isoformat'

Python version: 2.7.0, Jython version: 2.7.0, Django version: 1.8.6, django-jython version: 1.8.0b3, SQLITE JDBC version: 3.8.11.2

---

EDIT:

I created a Django App, with a single and simple model:

from django.db import models

class PMV(models.Model):
    creation_date = models.DateField()

I created an instance in the admin web page, with Date = today. When I tried to edit it, I got this:

After this, I added a models.DateTimeField() to the PMV model, created an instance and tried to edit it. I got the 'unicode' object has no attribute 'tzinfo' error again.

Answer 1

I think this can be readily explained:

1. sqlite3 lacks explicit datetime support as 'bobince' points out in the comments above
2. django.db.backends.sqlite3 works around this via storing as text in ISO-8601 format
3. but this is not part of JDBC support, which expects real datetime support

Note there is an outstanding bug to add complete sqlite3 support to Jython. I just adjusted the milestone for that bug to 2.7.2 (could be later). Such support is something we have wanted to do for a while, although it's a bit complicated because it's not just a question of using JDBC.

For the time being, this likely means you would to either do your own workaround (don't know scope); or switch to a database like MySQL or Apache Derby (small footprint like sqlite3, but with support for datetimes).