Django 1.7 迁移 - 日期时间类型错误

Question

我有一个大问题，我无法随心所欲地迁移我的数据库。我测试了很多东西（甚至直接写在数据库中......）。它与 Django 1.7.1 一起运行，我的数据库与 Sqlite3 一起存储。所以这是我的问题：

我有一个这样的模型：

from django.db import models
import datetime

class UserUsingTime(models.Model):
    userid = models.CharField(max_length = 30)
    using_time = models.DateTimeField(default = datetime.time())

（我想做的是存储一个计时器。例如，可能在比赛中的所有时间。）

我在模型的末尾添加了这一行：

app_name = models.CharField(max_length = 20, null = True)

然后我运行python manage makemigrations my_app_name，结果：

Migrations for 'my_app_name':
  0003_userusingtime_app_name.py:
    - Add field app_name to userusingtime

所以现在一切都很好:) 但是当我尝试运行 python manage migrate 时，我有大量的错误行：

    Operations to perform:
      Apply all migrations: admin, contenttypes, my_app_name, auth, sessions
    Running migrations:
      Applying my_app_name.0003_userusingtime_app_name...Traceback (most recent call last):
      File "./manage.py", line 8, in 
        execute_from_command_line(sys.argv)
      File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
        utility.execute()
      File "/usr/local/lib/python2.7/dist-packages/django/core/management/__init__.py", line 377, in execute
        self.fetch_command(subcommand).run_from_argv(self.argv)
      File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 288, in run_from_argv
        self.execute(*args, **options.__dict__)
      File "/usr/local/lib/python2.7/dist-packages/django/core/management/base.py", line 338, in execute
        output = self.handle(*args, **options)
      File "/usr/local/lib/python2.7/dist-packages/django/core/management/commands/migrate.py", line 160, in handle
        executor.migrate(targets, plan, fake=options.get("fake", False))
      File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 63, in migrate
        self.apply_migration(migration, fake=fake)
      File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/executor.py", line 97, in apply_migration
        migration.apply(project_state, schema_editor)
      File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/migration.py", line 107, in apply
        operation.database_forwards(self.app_label, schema_editor, project_state, new_state)
      File "/usr/local/lib/python2.7/dist-packages/django/db/migrations/operations/fields.py", line 37, in database_forwards
        field,
      File "/usr/local/lib/python2.7/dist-packages/django/db/backends/sqlite3/schema.py", line 167, in add_field
        self._remake_table(model, create_fields=[field])
      File "/usr/local/lib/python2.7/dist-packages/django/db/backends/sqlite3/schema.py", line 128, in _remake_table
        self.create_model(temp_model)
      File "/usr/local/lib/python2.7/dist-packages/django/db/backends/schema.py", line 209, in create_model
        definition, extra_params = self.column_sql(model, field)
      File "/usr/local/lib/python2.7/dist-packages/django/db/backends/schema.py", line 121, in column_sql
        default_value = self.effective_default(field)
      File "/usr/local/lib/python2.7/dist-packages/django/db/backends/schema.py", line 184, in effective_default
        default = field.get_db_prep_save(default, self.connection)
      File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/__init__.py", line 627, in get_db_prep_save
        prepared=False)
      File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/__init__.py", line 1286, in get_db_prep_value
        value = self.get_prep_value(value)
      File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/__init__.py", line 1269, in get_prep_value
        value = super(DateTimeField, self).get_prep_value(value)
      File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/__init__.py", line 1171, in get_prep_value
        return self.to_python(value)
      File "/usr/local/lib/python2.7/dist-packages/django/db/models/fields/__init__.py", line 1228, in to_python
        parsed = parse_datetime(value)
      File "/usr/local/lib/python2.7/dist-packages/django/utils/dateparse.py", line 70, in parse_datetime
        match = datetime_re.match(value)
    TypeError: expected string or buffer

所以我真的不知道下一步该做什么......另外，似乎有一个datetime 错误，我无法解释，因为我没有在我的模型中触摸任何datetime 对象......好奇怪！

请帮我解决这个问题 :) 我提前感谢你们（Y）！

Answer 1

您的using_time 字段定义有问题。 Django 抱怨是因为您试图将 time 对象存储在 datetime 容器中。

DateTimeField 对于您要表示的内容（时间长度）来说只是错误的字段类型。您可以将其切换为TimeField，或者简单地使用FloatField 或IntegerField 来存储秒或毫秒。

（为什么现在只抛出迁移错误？我认为这是因为这个错误没有在早期版本的 Django 中发现，这是你第一次真正的迁移（即不是最初的假迁移）已在 1.7 中尝试过。）