将kwargs传递到Django中的自定义字段

Question

我以这个问题作为创建自定义字段的基础：

Django文件上传大小限制

当我尝试进行迁移时，我收到一条错误消息，指出“ content_types”不在垃圾堆中。我已经调试了代码，几乎好像我的自定义字段init被调用了两次。一次是在我拥有此字段的模型中（带有kwarg），一次是不包含kwargs。

我引用了这篇文章： 如何在Django Rest Framework的自定义字段中传递其他关键字参数？

但是，无论解决方案怎么说，我已经在做。

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)

模型中的活动字段：

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'

stacktrace：

    (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)

Answer 1

我想出了解决方案：在自定义字段类中添加一个解构函数：def deconstruct(self):&nbsp; &nbsp; name, path, args, kwargs = super(MediaField, self).deconstruct()&nbsp; &nbsp; kwargs['content_types'] = self.content_types&nbsp; &nbsp; kwargs['max_upload_size'] = self.max_upload_size&nbsp; &nbsp; return name, path, args, kwargs