Question

我按照说明将Django应用程序从Django 1.6.11升级到1.8.1。除了 init .py之外，我已删除了所有迁移功能。然后我跑：

manage.py makemigrations

它崩溃了以下追溯：

Traceback (most recent call last):
File "manage.py", line 12, in <module>
  execute_from_command_line(sys.argv)
File "/Users/dwatson/Environments/website/lib/python2.7/site-packages/django/core/management/__init__.py", line 338, in execute_from_command_line
  utility.execute()
File "/Users/dwatson/Environments/website/lib/python2.7/site-packages/django/core/management/__init__.py", line 330, in execute
  self.fetch_command(subcommand).run_from_argv(self.argv)
File "/Users/dwatson/Environments/website/lib/python2.7/site-packages/django/core/management/base.py", line 390, in run_from_argv
  self.execute(*args, **cmd_options)
File "/Users/dwatson/Environments/website/lib/python2.7/site-packages/django/core/management/base.py", line 441, in execute
  output = self.handle(*args, **options)
File "/Users/dwatson/Environments/website/lib/python2.7/site-packages/django/core/management/commands/makemigrations.py", line 143, in handle
  self.write_migration_files(changes)
File "/Users/dwatson/Environments/website/lib/python2.7/site-packages/django/core/management/commands/makemigrations.py", line 171, in write_migration_files
  migration_string = writer.as_string()
File "/Users/dwatson/Environments/website/lib/python2.7/site-packages/django/db/migrations/writer.py", line 166, in as_string
  operation_string, operation_imports = OperationWriter(operation).serialize()
File "/Users/dwatson/Environments/website/lib/python2.7/site-packages/django/db/migrations/writer.py", line 124, in serialize
  _write(arg_name, arg_value)
File "/Users/dwatson/Environments/website/lib/python2.7/site-packages/django/db/migrations/writer.py", line 75, in _write
  arg_string, arg_imports = MigrationWriter.serialize(item)
File "/Users/dwatson/Environments/website/lib/python2.7/site-packages/django/db/migrations/writer.py", line 303, in serialize
  item_string, item_imports = cls.serialize(item)
File "/Users/dwatson/Environments/website/lib/python2.7/site-packages/django/db/migrations/writer.py", line 377, in serialize
  return cls.serialize_deconstructed(path, args, kwargs)
File "/Users/dwatson/Environments/website/lib/python2.7/site-packages/django/db/migrations/writer.py", line 268, in serialize_deconstructed
  arg_string, arg_imports = cls.serialize(arg)
File "/Users/dwatson/Environments/website/lib/python2.7/site-packages/django/db/migrations/writer.py", line 465, in serialize
  "topics/migrations/#migration-serializing" % (value, get_docs_version())
ValueError: Cannot serialize: <bound method AccountManager.gen_num of <coreapi.models.AccountManager object at 0x103925450>>
There are some values Django cannot serialize into migration files.
For more, see https://docs.djangoproject.com/en/1.8/topics/migrations/#migration-serializing

此函数是AccountManager类中定义的方法，它派生自models.Manager：

def gen_num(self):
    max_digits = 9
    candidate = random.randint(0, 10**max_digits)
    return candidate

我已经检查过返回候选行，并且正如预期的那样，它是一个int。

我假设此方法正在被内省，因为它被设置为关联字段的默认值：

num = models.PositiveIntegerField(
    _('Num'), help_text=_('Number, automatically-generated'),
    unique=True, blank=True, null=True, default=AccountManager().gen_num
)

Answer 1

解决方案是遵循这里给出的建议：

https://docs.djangoproject.com/en/1.8/topics/migrations/#migration-serializing

也就是说，将函数从Manager的类体移动到模块体：

def gen_num():
    max_digits = 9
    candidate = random.randint(0, 10**max_digits)
    return candidate

完成此更改后，makemigrations成功完成。

当makemigrations崩溃时，如何将Django app从1.6.11升级到1.8？

1 个答案: