Django rest框架```TypeError：**后的类型对象参数必须是映射，而不是int```被抛出答案

【问题标题】：Django rest framework ```TypeError: type object argument after ** must be a mapping, not int``` being thrownDjango rest框架```TypeError：**后的类型对象参数必须是映射，而不是int```被抛出
【发布时间】：2020-02-03 14:50:12
【问题描述】：

我有一个 SMSMessages 模型，它将包含所有发送的短信。我正在尝试通过 django-rest-framework ListCreateAPIView 类进行访问，但是当我尝试执行 OPTION 时，我一直遇到错误通过 Insomnia 请求 API，TypeError at /smsmessages/ type object argument after ** must be a mapping, not int。

我在 SO 上进行了搜索，发现了类似的错误，但它们是由 filter() 参数引起的，这不适用于此。我正在使用 django 2.2.5、python 3.6.8、django-rest-framework 3.10.3 和 mysqlclient 1.4.4。

这是SMSMessages的型号

from django.db import models
from django.contrib.auth.models import AbstractUser
from rest_framework.authtoken.models import Token

class SMSMessages(models.Model):
    sms_number_to = models.CharField(max_length=14)
    sms_content = models.CharField(max_length=160)
    sending_user = models.ForeignKey("SMSUser", on_delete=models.PROTECT, related_name="user_that_sent", limit_choices_to=1)
    sent_date = models.DateTimeField(auto_now=True)
    delivery_status = models.BooleanField(default=False)

    class Meta:
        verbose_name_plural = "SMSMessages"

    def __str__(self):
        return self.sending_user

这是 urls.py 文件：

from django.urls import path
from rest_framework.authtoken import views
from rest_framework.routers import DefaultRouter

from notification.apiviews import SMSendView, SMSMessagesView

app_name = "notification"

router = DefaultRouter()

urlpatterns = [
    path("smsmessages/", SMSMessagesView.as_view(), name="sms_messages"),
]

所以我访问它的方式是向http://localhost:8000/smsmessages/ 发送一个OPTION 请求。这是用于 api 视图的 SMSMessagesview 类：

from rest_framework import generics, status, viewsets, permissions
from rest_framework.response import Response
from rest_framework.views import APIView
from django.shortcuts import get_object_or_404, get_list_or_404
from django.contrib.auth import authenticate

from commons.models import SMSMessages
from commons.serializers import SMSMessagesSerializer


class SMSMessagesView(generics.ListCreateAPIView):

    """
    This class is responsible for generating, and returning, the view for all created objects of the SMSMessages model.
    It sub-classes the ListCreateAPIView class from the generics module.
    """
    queryset = SMSMessages.objects.all()
    if not queryset:
        Response(data={"{0} not found".format(queryset)}, status=404, content_type="application/json")

    serializer_class = SMSMessagesSerializer

这是错误：

TypeError at /notification/smsmessages/
type object argument after ** must be a mapping, not int

Request Method: OPTIONS
Request URL: http://localhost:8055/notification/smsmessages/
Django Version: 2.2.5
Python Executable: /home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/bin/python
Python Version: 3.6.8
Python Path: ['/home/gadd/vscodeworkspace/sms.et/api.sms.et', '/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python36.zip', '/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6', '/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/lib-dynload', '/usr/lib/python3.6', '/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages']
Server time: Sat, 5 Oct 2019 16:19:59 +0000
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'rest_framework',
 'rest_framework_swagger',
 'rest_framework.authtoken',
 'commons',
 'notification']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']


Traceback:

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
  34.             response = get_response(request)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  115.                 response = self.process_exception_by_middleware(e, request)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  113.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/django/views/decorators/csrf.py" in wrapped_view
  54.         return view_func(*args, **kwargs)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/django/views/generic/base.py" in view
  71.             return self.dispatch(request, *args, **kwargs)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/rest_framework/views.py" in dispatch
  505.             response = self.handle_exception(exc)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/rest_framework/views.py" in handle_exception
  465.             self.raise_uncaught_exception(exc)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/rest_framework/views.py" in raise_uncaught_exception
  476.         raise exc

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/rest_framework/views.py" in dispatch
  502.             response = handler(request, *args, **kwargs)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/rest_framework/views.py" in options
  516.         data = self.metadata_class().determine_metadata(request, self)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/rest_framework/metadata.py" in determine_metadata
  68.             actions = self.determine_actions(request, view)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/rest_framework/metadata.py" in determine_actions
  94.                 actions[method] = self.get_serializer_info(serializer)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/rest_framework/metadata.py" in get_serializer_info
  111.             for field_name, field in serializer.fields.items()

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/django/utils/functional.py" in __get__
  80.         res = instance.__dict__[self.name] = self.func(instance)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/rest_framework/serializers.py" in fields
  360.         for key, value in self.get_fields().items():

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/rest_framework/serializers.py" in get_fields
  1047.                 source, info, model, depth

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/rest_framework/serializers.py" in build_field
  1182.                 return self.build_relational_field(field_name, relation_info)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/rest_framework/serializers.py" in build_relational_field
  1257.         field_kwargs = get_relation_kwargs(field_name, relation_info)

File "/home/gadd/vscodeworkspace/sms.et/api.sms.et/api_env/lib/python3.6/site-packages/rest_framework/utils/field_mapping.py" in get_relation_kwargs
  255.             limit_choices_to = models.Q(**limit_choices_to)

Exception Type: TypeError at /notification/smsmessages/
Exception Value: type object argument after ** must be a mapping, not int

这是使用的序列化程序类：

from rest_framework import serializers
from rest_framework.authtoken.models import Token

from commons.models import SMSUser, SMSPrice, Type, SMSMessages

class SMSMessagesSerializer(serializers.ModelSerializer):
    """
    A class for serializing the SMSMessages model's data. It sub-classes the
    ModelSerializer class from serializer's module.
    """

    class Meta:
        model = SMSMessages
        fields = '__all__'

当我尝试通过管理界面将SMSMessages 对象添加到数据库时，也会引发同样的错误。有人可以帮忙吗？

【问题讨论】：

相关对象序列化错误。我想。
@NaveenJain 我不这么认为，我已经更新了问题并插入了序列化程序，除了它针对上述模型之外，它类似于我使用的另一个有效的模型。

标签： django python-3.x django-rest-framework typeerror

【解决方案1】：

那只是因为你使用了 limit_choices_to 的错误数据格式，它是由 Django 定义的。

可以使用字典、Q 对象或返回字典或 Q 对象的可调用对象。

所以这导致了错误：

sending_user = models.ForeignKey("SMSUser", on_delete=models.PROTECT, related_name="user_that_sent", limit_choices_to=1 # HERE)

因此，您可能需要清楚地在此处配置正确的过滤器，以便在您为模型选择 sending_user 时，Django 管理员将过滤数据。就像如果你想允许在管理页面上只为sending_user 选择is_superuser，那么你可以这样做：

limit_choices_to={
    'is_superuser': True,
}

【讨论】：

感谢您的帮助。但是我确实有一个问题，如果不麻烦的话，如果我想让它选择发送它的用户的实际公司怎么办（公司保存在用户表中）？
我不太清楚，你的意思是只允许选择与使用管理页面的用户具有相同公司名称的sending_user？
不，类似sending_user = models.ForeignKey("SMSUser", on_delete=models.PROTECT, related_name="user_that_sent", limit_choices_to={'company_name'})。这可能吗？
不，我认为不是。它应该带有一个您要过滤的值，例如，如果您只想允许拥有 company_name 的用户是 Google，那么它应该是这样的 limit_choices_to={'company_name': 'Google'}。
因为外键链接到用户模型，所以它将是用户而不是company_name。

【解决方案2】：

来自documentation for ForeignKey.limit_choices_to，它...

在使用 ModelForm 或管理员呈现此字段时设置此字段的可用选择限制（默认情况下，查询集中的所有对象都可供选择）。可以使用字典、Q 对象或返回字典或 Q 对象的可调用对象。

...但是在模型中，您设置了一个整数limit_choices_to=1，而这些都不是。

您是否打算使用 limit_choices_to={'id': 1} 之类的东西来限制具有该 ID 的 SMS 用户的选择？

【讨论】：

你是绝对正确的。我认为limit_choices_to 实际上是用来限制返回的选择，这就是我给它一个整数的原因。感谢您的帮助。