python - Django 日期时间声明错误

Question

我在 models.py 中添加了以下代码:

class Conference(models.Model):
    conf_name = models.CharField(max_length=250)
    location = models.CharField(max_length=500)     
    note = models.TextField(max_length=500)     
    note2 = models.TextField(max_length=500)     
    date_from = models.DateField()
    date_to = models.DateField()
    time_from = models.TimeField(default='HH:MM:ss')
    time_to = models.TimeField(default='HH:MM:ss')  

之后，我运行迁移命令并得到以下回溯:

WARNINGS:
?: (mysql.W002) MySQL Strict Mode is not set for database connection 'appadmin'
    HINT: MySQL's Strict Mode fixes many data integrity problems in MySQL, such as data truncation upon insertion, by escalating warnings into errors. It is strongly recommended you activate it. See: https://docs.djangoproject.com/en/1.11/ref/databases/#mysql-sql-mode
?: (mysql.W002) MySQL Strict Mode is not set for database connection 'default'
    HINT: MySQL's Strict Mode fixes many data integrity problems in MySQL, such as data truncation upon insertion, by escalating warnings into errors. It is strongly recommended you activate it. See: https://docs.djangoproject.com/en/1.11/ref/databases/#mysql-sql-mode
?: (urls.W005) URL namespace 'dev_app' isn't unique. You may not be able to reverse all URLs in this namespace
Operations to perform:
  Apply all migrations: admin, auth, contenttypes, dev_app, sessions
Running migrations:
  Applying dev_app.0016_auto_20180112_0630...Traceback (most recent call last):
  File "manage.py", line 22, in <module>
    execute_from_command_line(sys.argv)
  File "/usr/lib/python2.7/site-packages/django/core/management/__init__.py", line 363, in execute_from_command_line
    utility.execute()
  File "/usr/lib/python2.7/site-packages/django/core/management/__init__.py", line 355, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/usr/lib/python2.7/site-packages/django/core/management/base.py", line 283, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/usr/lib/python2.7/site-packages/django/core/management/base.py", line 330, in execute
    output = self.handle(*args, **options)
  File "/usr/lib/python2.7/site-packages/django/core/management/commands/migrate.py", line 204, in handle
    fake_initial=fake_initial,
  File "/usr/lib/python2.7/site-packages/django/db/migrations/executor.py", line 115, in migrate
    state = self._migrate_all_forwards(state, plan, full_plan, fake=fake, fake_initial=fake_initial)
  File "/usr/lib/python2.7/site-packages/django/db/migrations/executor.py", line 145, in _migrate_all_forwards
    state = self.apply_migration(state, migration, fake=fake, fake_initial=fake_initial)
  File "/usr/lib/python2.7/site-packages/django/db/migrations/executor.py", line 244, in apply_migration
    state = migration.apply(state, schema_editor)
  File "/usr/lib/python2.7/site-packages/django/db/migrations/migration.py", line 129, in apply
    operation.database_forwards(self.app_label, schema_editor, old_state, project_state)
  File "/usr/lib/python2.7/site-packages/django/db/migrations/operations/fields.py", line 86, in database_forwards
    field,
  File "/usr/lib/python2.7/site-packages/django/db/backends/mysql/schema.py", line 48, in add_field
    super(DatabaseSchemaEditor, self).add_field(model, field)
  File "/usr/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 414, in add_field
    definition, params = self.column_sql(model, field, include_default=True)
  File "/usr/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 154, in column_sql
    default_value = self.effective_default(field)
  File "/usr/lib/python2.7/site-packages/django/db/backends/base/schema.py", line 228, in effective_default
    default = field.get_db_prep_save(default, self.connection)
  File "/usr/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 766, in get_db_prep_save
    prepared=False)
  File "/usr/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 2277, in get_db_prep_value
    value = self.get_prep_value(value)
  File "/usr/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 2272, in get_prep_value
    return self.to_python(value)
  File "/usr/lib/python2.7/site-packages/django/db/models/fields/__init__.py", line 2259, in to_python
    params={'value': value},
django.core.exceptions.ValidationError: [u"'null' value has an invalid format. It must be in HH:MM[:ss[.uuuuuu]] format."]

即使我恢复了 models.py 中的代码，回溯仍然存在。

我需要帮助理解回溯。

在应用模型更改之前，代码可以正常运行。模型迁移正确。我还刷新了数据库并尝试再次迁移，它给出了相同的结果。

Answer 1

您的 time_from 和 time_to 默认值是错误的。您应该提供默认值而不是格式。如果您的模型是新的，请删除迁移文件(我认为dev_app.0016_auto_20180112_0630)更改默认值并再次运行manage.py makemigrations。