Django的REST框架单元测试ValueError异常：不能分配 “u'johnz'”： “Message.author” 必须是一个 “用户” 实例

Question

tests.py

from django.contrib.auth.models import User 
from django.core.urlresolvers import reverse 
from rest_framework import status 
from rest_framework.test import APITestCase, APIClient, RequestsClient, APIRequestFactory 
from rest_framework.authtoken.models import Token 
from views import MessageListView 


class CreateMessageTest(APITestCase): 
    def setUp(self): 
     self.client = APIRequestFactory() 
     self.user = User.objects.create_user(username='johnz', first_name='John', last_name='Doe', email='john@doe.com', password='johnny', id=3) 
     self.user.save() 
     self.token = Token.objects.create(user=self.user) 
     self.data = {"body": "I am sad", "author": self.user} 

    def test_loggedin_user_can_create_message(self): 
     header = {'HTTP_AUTHORIZATION': 'Token {}'.format(self.token)} 
     user_obj = User.objects.get(pk=self.user.pk) 
     request = self.client.post(reverse('message-list'), data=self.data, **header) 
     response = MessageListView.as_view()(request) 
     self.assertEqual(response.status_code, status.HTTP_201_CREATED) 

    def test_anonymous_cant_create_message(self): 
     request = self.client.post(reverse('message-list'), data=self.data) 
     response = MessageListView.as_view()(request) 

     self.assertEqual(response.status_code, status.HTTP_401_UNAUTHORIZED) 

回溯

Traceback (most recent call last): 
    File "/home/bkovacev/PycharmProjects/silver_logic_project/posts/tests.py", line 28, in test_loggedin_user_can_create_message 
    response = MessageListView.as_view()(request) 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/django/views/decorators/csrf.py", line 58, in wrapped_view 
    return view_func(*args, **kwargs) 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/django/views/generic/base.py", line 68, in view 
    return self.dispatch(request, *args, **kwargs) 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/rest_framework/views.py", line 477, in dispatch 
    response = self.handle_exception(exc) 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/rest_framework/views.py", line 437, in handle_exception 
    self.raise_uncaught_exception(exc) 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/rest_framework/views.py", line 474, in dispatch 
    response = handler(request, *args, **kwargs) 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/rest_framework/generics.py", line 243, in post 
    return self.create(request, *args, **kwargs) 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/rest_framework/mixins.py", line 21, in create 
    self.perform_create(serializer) 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/rest_framework/mixins.py", line 26, in perform_create 
    serializer.save() 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/rest_framework/serializers.py", line 214, in save 
    self.instance = self.create(validated_data) 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/rest_framework/serializers.py", line 902, in create 
    instance = ModelClass.objects.create(**validated_data) 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/django/db/models/manager.py", line 85, in manager_method 
    return getattr(self.get_queryset(), name)(*args, **kwargs) 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/django/db/models/query.py", line 397, in create 
    obj = self.model(**kwargs) 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/django/db/models/base.py", line 537, in __init__ 
    setattr(self, field.name, rel_obj) 
    File "/home/bkovacev/envs/silver_logic_project_env/local/lib/python2.7/site-packages/django/db/models/fields/related_descriptors.py", line 211, in __set__ 
    self.field.remote_field.model._meta.object_name, 
ValueError: Cannot assign "u'johnz'": "Message.author" must be a "User" instance. 

我看过其他线程类似于这个，检查我是否也引用了正确的用户模型，并且我尝试了很多事情，但没有运气。

我在做什么错？如果我将format='json'添加到self.client.post()，我会得到<User: john> is not JSON serializable。所以我不确定我做错了什么。

编辑：

新增models.py

from __future__ import unicode_literals 
from django.db import models 
from django.contrib.auth.models import User 
from django.contrib.postgres.fields import JSONField 


class Message(models.Model): 
    """ 

    """ 
    author = models.ForeignKey(
     User, on_delete=models.CASCADE, related_name='messages' 
    ) 
    created_at = models.DateTimeField(auto_now_add=True) 
    body = models.TextField(max_length=160) 
    sentiment = JSONField(blank=True, null=True) 

    def __str__(self): 
     return "%s, %s, %s" % (self.author, self.created_at, self.id) 

EDIT 2（加入串行和视图） EDIT 3（适于在串行器） serializers.py

class MessageSerializer(serializers.HyperlinkedModelSerializer): 

    author = UserSerializer() 

    class Meta: 
     model = Message 
     fields = ('author', 'sentiment', 'created_at', 'body', 'url') 

views.py

class MessageListView(generics.ListCreateAPIView): 
    """ 
    Class Based View that lists/creates Silver Logic(s) 
    """ 
    queryset = Message.objects.all() 
    serializer_class = MessageSerializer 
    permission_classes = (IsAuthenticatedOrReadOnly,) 
    pagination_class = PageNumberPagination 

Answer 1

事实是，模型中的作者引用了一个对象User。当您添加

author = serializers.CharField() 

它返回一个字符串。