Question

所以，我正在学习使用South，而且我一直在运行一些问题。我使用模型进行了初始应用程序迁移：

class Poll(models.Model):
    pass

然后添加我的字段......

class Poll(models.Model):
    question = models.CharField(max_length=200)
    pub_date = models.DateTimeField()

并且在迁移期间南方抱怨那些字段没有默认值，所以我输入了一些但是它没有用...现在当我尝试从模型中删除它们并迁移回空模式时我得到了以下追溯：

mirkocrocop@Mirkos-MacBook-Pro:~/workspace/toastdriven$ python manage.py migrate polls
Running migrations for polls:
 - Migrating forwards to 0007_auto__del_field_poll_question.
 > polls:0003_auto__add_field_poll_question__add_field_poll_pub_date
Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/django/core/management/__init__.py", line 443, in execute_from_command_line
    utility.execute()
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/django/core/management/__init__.py", line 382, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/django/core/management/base.py", line 196, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/django/core/management/base.py", line 232, in execute
    output = self.handle(*args, **options)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/south/management/commands/migrate.py", line 108, in handle
    ignore_ghosts = ignore_ghosts,
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/south/migration/__init__.py", line 213, in migrate_app
    success = migrator.migrate_many(target, workplan, database)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/south/migration/migrators.py", line 235, in migrate_many
    result = migrator.__class__.migrate_many(migrator, target, migrations, database)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/south/migration/migrators.py", line 310, in migrate_many
    result = self.migrate(migration, database)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/south/migration/migrators.py", line 133, in migrate
    result = self.run(migration)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/south/migration/migrators.py", line 106, in run
    dry_run.run_migration(migration)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/south/migration/migrators.py", line 191, in run_migration
    self._run_migration(migration)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/south/migration/migrators.py", line 178, in _run_migration
    raise exceptions.FailedDryRun(migration, sys.exc_info())
south.exceptions.FailedDryRun:  ! Error found during dry run of '0003_auto__add_field_poll_question__add_field_poll_pub_date'! Aborting.
Traceback (most recent call last):
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/south/migration/migrators.py", line 175, in _run_migration
    migration_function()
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/south/migration/migrators.py", line 57, in <lambda>
    return (lambda: direction(orm))
  File "/Users/mirkocrocop/workspace/toastdriven/polls/migrations/0003_auto__add_field_poll_question__add_field_poll_pub_date.py", line 19, in forwards
    keep_default=False)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/south/db/sqlite3.py", line 31, in add_column
    field.column: self._column_sql_for_create(table_name, name, field, False),
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/south/db/sqlite3.py", line 189, in _column_sql_for_create
    sql = self.column_sql(table_name, name, field, with_name=False, field_prepared=True)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/south/db/generic.py", line 688, in column_sql
    default = field.get_db_prep_save(default, connection=self._get_connection())
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 292, in get_db_prep_save
    prepared=False)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 816, in get_db_prep_value
    value = self.get_prep_value(value)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 801, in get_prep_value
    value = self.to_python(value)
  File "/Users/mirkocrocop/.virtualenvs/toastdriven/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 785, in to_python
    raise exceptions.ValidationError(msg)
ValidationError: [u"'0' value has an invalid format. It must be in YYYY-MM-DD HH:MM[:ss[.uuuuuu]][TZ] format."]

我如何解决这个问题，添加这些字段+从空模型迁移到字段填充模型的正确方法是什么？我一直在浏览南方的文档，但我没有得到它......我做了所有事情according to the documentation，但我不确定我应该将DateTimeField默认为...

Answer 1

当您必须提供默认值时，您正在与python解释器进行交互。如上所述，datetime模块在该时间点可用。要在这种情况下为DateTimeField提供默认值，只需提供datetime对象：

# Use the current date and time
datetime.datetime.now()
# Or a specific date and time
datetime.datetime(2012, 10, 1, 17, 30, 0, 0)

Django-South迁移期间的ValidationError

1 个答案: