python - Django 1.7 makemigrations - ValueError : Cannot serialize class

Question

我在从 Django 1.6.11 升级到 1.7 时遇到了一个有趣的问题。这似乎是基于我目前拆分文件的方式。目前，由于方法数量巨大，模型方法存储在与模型不同的文件中。

例如拆分如下:

help
|_ modelmethods
|  |_ __init__.py
|  |_ thread_methods.py
|_ __init__.py
|_ models.py

帮助应用文件夹中的 __init__.py 如下所示:

""" __init__.py for help app."""

from help.modelmethods.thread_methods import *

thread_methods.py 看起来像这样:

"""Methods for the Thread model."""

from help.models import Thread

class ThreadMethods:

    """Adds methods on to the Thread model."""

    def do_the_thing(self):
        pass

Thread.__bases__ += (ThreadMethods,)

我从中看到的错误如下:

Migrations for 'help':
  0001_initial.py:
    - Create model Thread
Traceback (most recent call last):
  File "manage.py", line 10, in <module>
    execute_from_command_line(sys.argv)
  File "/Users/user/.virtualenvs/stuff/lib/python2.7/site-packages/django/core/management/__init__.py", line 385, in execute_from_command_line
    utility.execute()
  File "/Users/user/.virtualenvs/stuff/lib/python2.7/site-packages/django/core/management/__init__.py", line 377, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/Users/user/.virtualenvs/stuff/lib/python2.7/site-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **options.__dict__)
  File "/Users/user/.virtualenvs/stuff/lib/python2.7/site-packages/django/core/management/base.py", line 338, in execute
    output = self.handle(*args, **options)
  File "/Users/user/.virtualenvs/stuff/lib/python2.7/site-packages/django/core/management/commands/makemigrations.py", line 124, in handle
    self.write_migration_files(changes)
  File "/Users/user/.virtualenvs/stuff/lib/python2.7/site-packages/django/core/management/commands/makemigrations.py", line 152, in write_migration_files
    migration_string = writer.as_string()
  File "/Users/user/.virtualenvs/stuff/lib/python2.7/site-packages/django/db/migrations/writer.py", line 129, in as_string
    operation_string, operation_imports = OperationWriter(operation).serialize()
  File "/Users/user/.virtualenvs/stuff/lib/python2.7/site-packages/django/db/migrations/writer.py", line 86, in serialize
    arg_string, arg_imports = MigrationWriter.serialize(arg_value)
  File "/Users/user/.virtualenvs/stuff/lib/python2.7/site-packages/django/db/migrations/writer.py", line 245, in serialize
    item_string, item_imports = cls.serialize(item)
  File "/Users/user/.virtualenvs/stuff/lib/python2.7/site-packages/django/db/migrations/writer.py", line 380, in serialize
    raise ValueError("Cannot serialize: %r\nThere are some values Django cannot serialize into migration files.\nFor more, see https://docs.djangoproject.com/en/dev/topics/migrations/#migration-serializing" % value)
ValueError: Cannot serialize: <class help.modelmethods.thread_methods.ThreadMethods at 0x1105c3870>
There are some values Django cannot serialize into migration files.
For more, see https://docs.djangoproject.com/en/dev/topics/migrations/#migration-serializing

我意识到它正在尝试序列化该类并因此而窒息。有没有解决这个问题并保持分离的好方法？或者唯一可比较的方法是将 models.py 文件分解为具有适当 __init__.py 设置的模型文件夹，并且每个文件都专用于一个模型包含所有相关方法(以及确保没有引入循环导入)。

Answer 1

由于自定义验证器，我无法迁移。我的问题是我没有读过 the manual正确地，它说:

If a class-based validator is used in the validators model field option, you should make sure it is serializable by the migration framework by adding deconstruct() and __eq__() methods.

指向migrations-docs这解释了为什么您需要 deconstruct() 和 __eq__() 以及如何编写它们。

也应该适用于其他类，而不仅仅是验证器。