Python 在序列化程序Django rest框架中处理文件？

我在serializer.py中有一个文件字段，需要为文件字段编写自定义验证。我编写的代码如下：

类SendMessageSerializer（serializers.ModelSerializer）：

调用此函数时，显示以下错误：

TypeError at /chat-message/send/
string indices must be integers
Request Method: POST
Request URL:    http://127.0.0.1:8001/chat-message/send/
Django Version: 1.6
Exception Type: TypeError
Exception Value:    
string indices must be integers
Exception Location: /home/something/projects/something/apps/chats/serializer.py in validate_file, line 13
Python Executable:  /home/something/Virtualenv/something/bin/python
Python Version: 2.7.6
Python Path:    
['/home/ntech/projects/something',
 '/home/ntech/Virtualenv/something/lib/python2.7',
 '/home/ntech/Virtualenv/something/lib/python2.7/plat-i386-linux-gnu',
 '/home/ntech/Virtualenv/something/lib/python2.7/lib-tk',
 '/home/ntech/Virtualenv/something/lib/python2.7/lib-old',
 '/home/ntech/Virtualenv/something/lib/python2.7/lib-dynload',
 '/usr/lib/python2.7',
 '/usr/lib/python2.7/plat-i386-linux-gnu',
 '/usr/lib/python2.7/lib-tk',
 '/home/ntech/Virtualenv/something/local/lib/python2.7/site-packages',
 '/home/ntech/Virtualenv/something/lib/python2.7/site-packages']
Server time:    Fri, 2 Jan 2015 09:33:35 +0000

---

我需要检查字段是否为文件，如何检查，是否有获取文件的替代解决方案

请向我们展示您的序列化程序的所有代码。@zymud我已经更新了。这是序列化程序中的代码。谢谢，请告诉我您使用的django rest框架的版本是什么？@zymud我使用的djangorestframework==2.4.4。目前我只看到一个错误-方法

验证_文件

必须返回

attrs

（不是

文件

）。但我不认为这会导致你的异常。请在异常之前向我显示

attrs

变量的值（您可以使用断点或仅打印它）。

TypeError at /chat-message/send/
string indices must be integers
Request Method: POST
Request URL:    http://127.0.0.1:8001/chat-message/send/
Django Version: 1.6
Exception Type: TypeError
Exception Value:    
string indices must be integers
Exception Location: /home/something/projects/something/apps/chats/serializer.py in validate_file, line 13
Python Executable:  /home/something/Virtualenv/something/bin/python
Python Version: 2.7.6
Python Path:    
['/home/ntech/projects/something',
 '/home/ntech/Virtualenv/something/lib/python2.7',
 '/home/ntech/Virtualenv/something/lib/python2.7/plat-i386-linux-gnu',
 '/home/ntech/Virtualenv/something/lib/python2.7/lib-tk',
 '/home/ntech/Virtualenv/something/lib/python2.7/lib-old',
 '/home/ntech/Virtualenv/something/lib/python2.7/lib-dynload',
 '/usr/lib/python2.7',
 '/usr/lib/python2.7/plat-i386-linux-gnu',
 '/usr/lib/python2.7/lib-tk',
 '/home/ntech/Virtualenv/something/local/lib/python2.7/site-packages',
 '/home/ntech/Virtualenv/something/lib/python2.7/site-packages']
Server time:    Fri, 2 Jan 2015 09:33:35 +0000