python – 在Django REST框架中添加不在模型中的序列化程序的字段

我有一个模型注释,创建时可能会创建一个新用户,也可能不会创建新的用户因此,在创建新注释时,我的API需要一个密码字段.这是我的评论模特：

class Comment(models.Model):
    commenter = models.ManyToManyField(Commenter)
    email = models.EmailField(max_length=100)
    author = models.CharField(max_length=100)
    url = models.URLField(max_length=200)
    content = models.TextField(blank=True,null=True)
    ip = models.IPAddressField(max_length=45)
    date = models.DateTimeField(default=datetime.now)
    post_title = models.CharField(max_length=200)
    post_url = models.URLField(max_length=200)
    rating = models.IntegerField(max_length=10,default=0)

这是我的API视图：

class CommentNewView(CreateAPIView):
    model = Comment
    serializer_class = CommentCreateSerializer

这是我的串行器：

class CommentCreateSerializer(serializers.ModelSerializer):
    commenter_pw = serializers.CharField(max_length=32,required=False)

    class Meta:
        model = Comment
        fields = ('email','author','url','content','ip','post_title','post_url','commenter_pw')

这是我得到的错误：

Environment:


Request Method: POST
Request URL: http://127.0.0.1:8000/api/comment/create/

Django Version: 1.5.2
Python Version: 2.7.2
Installed Applications:
('commentflow.apps.dashboard','commentflow.apps.commenter','commentflow.apps.comment','rest_framework','rest_framework.authtoken','django.contrib.auth','django.contrib.contenttypes','django.contrib.sessions','django.contrib.sites','django.contrib.messages','django.contrib.staticfiles','django.contrib.admin','django.contrib.admindocs')
Installed Middleware:
('django.middleware.common.CommonMiddleware','django.contrib.sessions.middleware.SessionMiddleware','django.middleware.locale.LocaleMiddleware','django.middleware.csrf.CsrfViewMiddleware','django.contrib.auth.middleware.AuthenticationMiddleware','django.contrib.messages.middleware.MessageMiddleware')


Traceback:
File "/Users/tlovett1/.virtualenvs/commentflow/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  115.                         response = callback(request,*callback_args,**callback_kwargs)
File "/Users/tlovett1/.virtualenvs/commentflow/lib/python2.7/site-packages/django/views/generic/base.py" in view
  68.             return self.dispatch(request,*args,**kwargs)
File "/Users/tlovett1/.virtualenvs/commentflow/lib/python2.7/site-packages/django/views/decorators/csrf.py" in wrapped_view
  77.         return view_func(*args,**kwargs)
File "/Users/tlovett1/.virtualenvs/commentflow/lib/python2.7/site-packages/rest_framework/views.py" in dispatch
  327.             response = self.handle_exception(exc)
File "/Users/tlovett1/.virtualenvs/commentflow/lib/python2.7/site-packages/rest_framework/views.py" in dispatch
  324.             response = handler(request,**kwargs)
File "/Users/tlovett1/.virtualenvs/commentflow/lib/python2.7/site-packages/rest_framework/generics.py" in post
  372.         return self.create(request,**kwargs)
File "/Users/tlovett1/.virtualenvs/commentflow/lib/python2.7/site-packages/rest_framework/mixins.py" in create
  50.         if serializer.is_valid():
File "/Users/tlovett1/.virtualenvs/commentflow/lib/python2.7/site-packages/rest_framework/serializers.py" in is_valid
  479.         return not self.errors
File "/Users/tlovett1/.virtualenvs/commentflow/lib/python2.7/site-packages/rest_framework/serializers.py" in errors
  471.                 ret = self.from_native(data,files)
File "/Users/tlovett1/.virtualenvs/commentflow/lib/python2.7/site-packages/rest_framework/serializers.py" in from_native
  867.         instance = super(ModelSerializer,self).from_native(data,files)
File "/Users/tlovett1/.virtualenvs/commentflow/lib/python2.7/site-packages/rest_framework/serializers.py" in from_native
  324.             return self.restore_object(attrs,instance=getattr(self,'object',None))
File "/Users/tlovett1/.virtualenvs/commentflow/lib/python2.7/site-packages/rest_framework/serializers.py" in restore_object
  852.             instance = self.opts.model(**attrs)
File "/Users/tlovett1/.virtualenvs/commentflow/lib/python2.7/site-packages/django/db/models/base.py" in __init__
  415.                 raise TypeError("'%s' is an invalid keyword argument for this function" % list(kwargs)[0])

Exception Type: TypeError at /api/comment/create/
Exception Value: 'commenter_pw' is an invalid keyword argument for this function

解决方法

如果有任何人好奇,解决方案是覆盖restore_object方法,并在注释对象实例化之后添加额外的实例变量：

def restore_object(self,attrs,instance=None):
        if instance is not None:
            instance.email = attrs.get('email',instance.email)
            instance.author = attrs.get('author',instance.author)
            instance.url = attrs.get('url',instance.url)
            instance.content = attrs.get('content',instance.content)
            instance.ip = attrs.get('ip',instance.ip)
            instance.post_title = attrs.get('post_title',instance.post_title)
            instance.post_url = attrs.get('post_url',instance.post_url)
            return instance

        commenter_pw = attrs.get('commenter_pw')
        del attrs['commenter_pw']

        comment = Comment(**attrs)
        comment.commenter_password = commenter_pw

        return comment