Django 1.7.1 custom field failing when running tests

Question

I have just upgraded my Django 1.6.5 project to Django 1.7.1. I followed the steps documented to move from South to Django 1.7.1 and it works perfectly.

The issue I have is when I run "python manage.py test" on my project, it fails with the error:

Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
    utility.execute()
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 377, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/core/management/commands/test.py", line 50, in run_from_argv
    super(Command, self).run_from_argv(argv)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/core/management/commands/test.py", line 71, in execute
    super(Command, self).execute(*args, **options)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/core/management/base.py", line 338, in execute
    output = self.handle(*args, **options)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/core/management/commands/test.py", line 88, in handle
    failures = test_runner.run_tests(test_labels)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/test/runner.py", line 147, in run_tests
    old_config = self.setup_databases()
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/test/runner.py", line 109, in setup_databases
    return setup_databases(self.verbosity, self.interactive, **kwargs)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/test/runner.py", line 299, in setup_databases
    serialize=connection.settings_dict.get("TEST", {}).get("SERIALIZE", True),
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/db/backends/creation.py", line 377, in create_test_db
    test_flush=True,
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/core/management/__init__.py", line 115, in call_command
    return klass.execute(*args, **defaults)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/core/management/base.py", line 338, in execute
    output = self.handle(*args, **options)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 160, in handle
    executor.migrate(targets, plan, fake=options.get("fake", False))
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 63, in migrate
    self.apply_migration(migration, fake=fake)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/db/migrations/executor.py", line 97, in apply_migration
    migration.apply(project_state, schema_editor)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/db/migrations/migration.py", line 107, in apply
    operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/db/migrations/operations/models.py", line 36, in database_forwards
    schema_editor.create_model(model)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/db/backends/schema.py", line 209, in create_model
    definition, extra_params = self.column_sql(model, field)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/db/backends/schema.py", line 121, in column_sql
    default_value = self.effective_default(field)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/db/backends/schema.py", line 184, in effective_default
    default = field.get_db_prep_save(default, self.connection)
  File "/home/mark/.virtualenvs/clippy/local/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 627, in get_db_prep_save
    prepared=False)
  File "/home/mark/projects/clippy/core/fields.py", line 21, in get_db_prep_value
    return int(time.mktime(value.timetuple()))
AttributeError: 'NoneType' object has no attribute 'timetuple'

I believe this is as a result of a custom field I use to store date/time fields as timestamp integers in the database. The code for this is:

class UnixDateTimeField(models.DateTimeField):
    __metaclass__ = models.SubfieldBase

    def get_internal_type(self):
        return 'PositiveIntegerField'

    def to_python(self, value):
        if value is None or isinstance(value, datetime):
            return value
        if isinstance(value, date):
            return datetime(value.year, value.month, value.day, 0, 0, 0, 0, utc)
        return datetime.utcfromtimestamp(float(value)).replace(tzinfo=utc)

    def get_db_prep_value(self, value, connection, prepared=False):
        return int(time.mktime(value.timetuple()))

    def value_to_string(self, obj):
        value = self._get_val_from_obj(obj)
        return self.to_python(value).strftime('%Y-%m-%d %H:%M:%S %Z')

This happens even if I remove ALL unit tests from my project. Does anyone know what is causing this? It worked fine before upgrading to Django 1.7.1.

Answer 1

I solved this by adding the following to the get_db_prep_value() method in my field:

if value is None:
    return value

So the total field becomes:

class UnixDateTimeField(models.DateTimeField):
    __metaclass__ = models.SubfieldBase

    def get_internal_type(self):
        return 'PositiveIntegerField'

    def to_python(self, value):
        if value is None or isinstance(value, datetime):
            return value
        if isinstance(value, date):
            return datetime(value.year, value.month, value.day, 0, 0, 0, 0, utc)
        return datetime.utcfromtimestamp(float(value)).replace(tzinfo=utc)

    def get_db_prep_value(self, value, connection, prepared=False):

        if value is None:
            return value

        return int(time.mktime(value.timetuple()))

    def value_to_string(self, obj):
        value = self._get_val_from_obj(obj)
        return self.to_python(value).strftime('%Y-%m-%d %H:%M:%S %Z')

This solved this issue and now the tests work.

Answer 2

I also have some kind of errors using Django Custom Fields and I think problem is the around the migration system of Django.

Try to squash / remove the migrations ( https://docs.djangoproject.com/en/1.7/topics/migrations/#squashing-migrations )