将 kwargs 传递给 Django 中的自定义字段

debugcn 发表于 Dev

约翰

我使用这个问题作为创建自定义字段的基础：

当我尝试 makemigrations 时，我收到一条错误消息，指出“content_types”不在 kwargs 中。我已经调试了代码，看起来我的自定义字段init几乎被调用了两次。一次来自我拥有此字段的模型（带有 kwargs），一次不包含 kwargs。

我参考了这篇文章：How to pass additional keyword arguments in a custom Field in Django Rest Framework？

但是，我已经在做解决方案所说的任何事情。

class MediaField(FileField):
    def __init__(self, *args, **kwargs):
        self.content_types = kwargs.pop('content_types')
        self.max_upload_size = kwargs.pop('max_upload_size')

        super(MediaField, self).__init__(*args, **kwargs)

模型中的作用域：

media = MediaField(upload_to='media',  # this will create a folder in MEDIA_ROOT
                   content_types=['jpeg', 'jpg', 'png'],
                   max_upload_size=5242880)

错误： KeyError: 'content_types'

堆栈跟踪：

    (efs-cP0vQdei) user@right:~/Documents/websites/efs$ ./manage.py makemigrations
Traceback (most recent call last):
  File "./manage.py", line 15, in <module>
    execute_from_command_line(sys.argv)
  File "/home/user/.local/share/virtualenvs/efs-cP0vQdei/lib/python3.6/site-packages/django/core/management/__init__.py", line 371, in execute_from_command_line
    utility.execute()
  File "/home/user/.local/share/virtualenvs/efs-cP0vQdei/lib/python3.6/site-packages/django/core/management/__init__.py", line 365, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/user/.local/share/virtualenvs/efs-cP0vQdei/lib/python3.6/site-packages/django/core/management/base.py", line 288, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/user/.local/share/virtualenvs/efs-cP0vQdei/lib/python3.6/site-packages/django/core/management/base.py", line 335, in execute
    output = self.handle(*args, **options)
  File "/home/user/.local/share/virtualenvs/efs-cP0vQdei/lib/python3.6/site-packages/django/core/management/commands/makemigrations.py", line 133, in handle
    ProjectState.from_apps(apps),
  File "/home/user/.local/share/virtualenvs/efs-cP0vQdei/lib/python3.6/site-packages/django/db/migrations/state.py", line 222, in from_apps
    model_state = ModelState.from_model(model)
  File "/home/user/.local/share/virtualenvs/efs-cP0vQdei/lib/python3.6/site-packages/django/db/migrations/state.py", line 411, in from_model
    fields.append((name, field.clone()))
  File "/home/user/.local/share/virtualenvs/efs-cP0vQdei/lib/python3.6/site-packages/django/db/models/fields/__init__.py", line 470, in clone
    return self.__class__(*args, **kwargs)
  File "/home/user/Documents/websites/efs/ssadventures/customfields.py", line 23, in __init__
    self.content_types = kwargs.pop('content_types')
KeyError: 'content_types'

约翰

我想出了解决方案：

向自定义字段类添加解构：

def deconstruct(self):
    name, path, args, kwargs = super(MediaField, self).deconstruct()

    kwargs['content_types'] = self.content_types
    kwargs['max_upload_size'] = self.max_upload_size

    return name, path, args, kwargs

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