python - 类型错误 : "ModelBase is not iterable"

Question

我正在开发一个小项目来练习 Django REST Framework(以及后来的 React 前端)，然后再将我学到的技能应用到更大的公司项目中。

该项目是一个后端 API，允许人们查看《费城永远阳光明媚》每一集中主角犯下的潜在犯罪和侵权行为。为此，我做了this GitHub 存储库并在其中放入 Django 项目。

我发现自己在浏览器调试 View 中遇到错误，当我为网站添加新模型/序列化器/ View 时，我不太能弄清楚:

Environment:


Request Method: GET
Request URL: http://127.0.0.1:8000/characters/

Django Version: 1.10.6
Python Version: 3.6.0
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'rest_framework',
 'offense_api.apps.OffenseApiConfig']
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 "/Users/person/.virtualenvs/IASIP/lib/python3.6/site-packages/django/core/handlers/exception.py" in inner
  42.             response = get_response(request)

File "/Users/person/.virtualenvs/IASIP/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  187.                 response = self.process_exception_by_middleware(e, request)

File "/Users/person/.virtualenvs/IASIP/lib/python3.6/site-packages/django/core/handlers/base.py" in _get_response
  185.                 response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "/Users/person/.virtualenvs/IASIP/lib/python3.6/site-packages/django/views/decorators/csrf.py" in wrapped_view
  58.         return view_func(*args, **kwargs)

File "/Users/person/Workspace/IASIP_API/offense_api/views.py" in character_list
  70.         return JsonResponse(serializer.data, safe=False)

File "/Users/person/.virtualenvs/IASIP/lib/python3.6/site-packages/rest_framework/serializers.py" in data
  729.         ret = super(ListSerializer, self).data

File "/Users/person/.virtualenvs/IASIP/lib/python3.6/site-packages/rest_framework/serializers.py" in data
  262.                 self._data = self.to_representation(self.instance)

File "/Users/person/.virtualenvs/IASIP/lib/python3.6/site-packages/rest_framework/serializers.py" in to_representation
  647.             self.child.to_representation(item) for item in iterable

Exception Type: TypeError at /characters/
Exception Value: 'ModelBase' object is not iterable

这只发生在“角色”页面上，该页面应该与我的其他 ListView (季节列表)相同。

序列化器.py

from rest_framework import serializers
from offense_api.models import Season, Episode, Character


class SeasonSerializer(serializers.ModelSerializer):
    episodes = serializers.StringRelatedField(many=True)

    class Meta:
        model = Season
        fields = ('season_number', 'episodes')


class EpisodeSerializer(serializers.ModelSerializer):

    class Meta:
        model = Episode
        fields = ('episode_number', 'episode_title', 'episode_season')


class CharacterSerializer(serializers.ModelSerializer):

    class Meta:
        model = Character
        fields = ('character_legal_first_name', 'character_legal_last_name', 'character_preferred_name',)

模型.py

from django.db import models


class Season(models.Model):
    season_created = models.DateTimeField(auto_now_add=True)
    season_number = models.IntegerField(unique=True)

    def __unicode__(self):
        return self.season_number

    def __str__(self):
        return str(self.season_number)


class Episode(models.Model):
    episode_season = models.ForeignKey(Season, related_name='episodes', on_delete=models.CASCADE)
    episode_created = models.DateTimeField(auto_now_add=True)
    episode_number = models.IntegerField()
    episode_title = models.CharField(max_length=300, default='')

    def __unicode__(self):
        return '%d. %d' % (self.episode_season.season_number, self.episode_number)

    def __str__(self):
        return '%d. %d' % (self.episode_season.season_number, self.episode_number)

    class Meta:
        unique_together = ('episode_season', 'episode_number')
        ordering = ('episode_number',)


class Character(models.Model):
    character_created = models.DateTimeField(auto_now_add=True)
    character_legal_first_name = models.CharField(max_length=50, default='', null=True)
    character_legal_last_name = models.CharField(max_length=100, default='', null=True)
    character_preferred_name = models.CharField(max_length=150, default='', primary_key=True)

    def __unicode__(self):
        return self.character_preferred_name

    def __str__(self):
        return self.character_preferred_name

    class Meta:
        ordering = ('character_preferred_name',)

Views.py

from django.http import HttpResponse, JsonResponse
from django.views.decorators.csrf import csrf_exempt
from rest_framework.renderers import JSONRenderer
from rest_framework.parsers import JSONParser
from offense_api.models import Episode, Season, Character
from offense_api.serializers import EpisodeSerializer, SeasonSerializer, CharacterSerializer


@csrf_exempt
def season_list(request):
    """
    List all seasons, or create a new one.
    :param request: 
    :return: 
    """
    if request.method == 'GET':
        seasons = Season.objects.all()
        serializer = SeasonSerializer(seasons, many=True)
        return JsonResponse(serializer.data, safe=False)

    elif request.method == 'POST':
        data = JSONParser().parse(request)
        serializer = SeasonSerializer(data=data)
        if serializer.is_valid():
            serializer.save()
            return JsonResponse(serializer.data, status=201)
        return JsonResponse(serializer.errors, status=400)


@csrf_exempt
def season_detail(request, pk):
    """
    Retrieve, update, or delete a season.
    :param request: 
    :param pk: 
    :return: 
    """
    try:
        season = Season.objects.get(pk=pk)
    except Season.DoesNotExist:
        return HttpResponse(status=404)

    if request.method == 'GET':
        serializer = SeasonSerializer(season)
        return JsonResponse(serializer.data)

    elif request.method == 'PUT':
        data = JSONParser().parse(request)
        serializer = SeasonSerializer(season, data=data)
        if serializer.is_valid():
            serializer.save()
            return JsonResponse(serializer.data)
        return JsonResponse(serializer.errors, status=400)

    elif request.method == 'DELETE':
        season.delete()
        return HttpResponse(status=204)


@csrf_exempt
def character_list(request):
    """
        List all characters, or create a new one.
        :param request: 
        :return: 
        """
    if request.method == 'GET':
        characters = Character.objects.all()
        serializer = CharacterSerializer(Character, many=True)
        return JsonResponse(serializer.data, safe=False)

    elif request.method == 'POST':
        data = JSONParser().parse(request)
        serializer = CharacterSerializer(data=data)
        if serializer.is_valid():
            serializer.save()
            return JsonResponse(serializer.data, status=201)
        return JsonResponse(serializer.errors, status=400)

Urls.py

from django.conf.urls import url
from offense_api import views

urlpatterns = [
    url(r'^seasons/$', views.season_list),
    url(r'^seasons/(?P<pk>[0-9]+)/$', views.season_detail),
    url(r'^characters/$', views.character_list),
]

需要修改哪些内容才能避免此错误？

Answer 1

在views.py中，您将类Character传递给序列化器。您应该传递数据字符。

也不要使用首选名称作为主键，它很容易变得不唯一