当我尝试设置会话值 (Django) 时，出现 TypeError (Object ... is not JSON serializable)。为什么？

Question

当我尝试在视图中（在 basket 应用程序中）设置会话值时，出现了这个奇怪的 TypeError：“产品类型的对象不是 JSON 可序列化的”。错误发生在 request.session['Hello'] = 'foo'。

不过，这个错误不会发生在其他地方。例如，在 store 应用程序中，在 views.py 中，以下 request.session['Hello World'] = 'Alloy' 效果很好。

你知道为什么吗？

篮子应用程序/views.py

（有问题）

from django.shortcuts import render, get_object_or_404
from django.http import JsonResponse

from . basket import Basket
from store.models import Product
from discount.forms import UserDiscountForm


def basket_summary(request):
    basket = Basket(request)
    context = {'basket':basket}
    request.session['Hello'] = 'foo'
    return render(request,"store/basket_summary.html",context)

商店应用程序/views.py

（效果很好）

from django.shortcuts import get_object_or_404, render
from requests.sessions import session

from .models import Category, Product



def home(request):
    print('----------// HOME PAGE  //----------')
    request.session['Hello World'] = 'Alloy'
    context = {}
    return render(request, 'store/home.html', context)

追溯

Environment:


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

Django Version: 3.2
Python Version: 3.9.4
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'store',
 'account',
 'basket',
 'orders',
 'payment',
 'contact',
 'address',
 'discount',
 'shipping']
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 (most recent call last):
  File "C:\Users\Utilisateur\Documents\Environments\monoi_django_virtualenv\lib\site-packages\django\core\handlers\exception.py", line 47, in inner
    response = get_response(request)
  File "C:\Users\Utilisateur\Documents\Environments\monoi_django_virtualenv\lib\site-packages\django\utils\deprecation.py", line 119, in __call__
    response = self.process_response(request, response)
  File "C:\Users\Utilisateur\Documents\Environments\monoi_django_virtualenv\lib\site-packages\django\contrib\sessions\middleware.py", line 61, in process_response
    request.session.save()
  File "C:\Users\Utilisateur\Documents\Environments\monoi_django_virtualenv\lib\site-packages\django\contrib\sessions\backends\db.py", line 83, in save
    obj = self.create_model_instance(data)
  File "C:\Users\Utilisateur\Documents\Environments\monoi_django_virtualenv\lib\site-packages\django\contrib\sessions\backends\db.py", line 70, in create_model_instance
    session_data=self.encode(data),
  File "C:\Users\Utilisateur\Documents\Environments\monoi_django_virtualenv\lib\site-packages\django\contrib\sessions\backends\base.py", line 114, in encode
    return signing.dumps(
  File "C:\Users\Utilisateur\Documents\Environments\monoi_django_virtualenv\lib\site-packages\django\core\signing.py", line 110, in dumps
    return TimestampSigner(key, salt=salt).sign_object(obj, serializer=serializer, compress=compress)
  File "C:\Users\Utilisateur\Documents\Environments\monoi_django_virtualenv\lib\site-packages\django\core\signing.py", line 172, in sign_object
    data = serializer().dumps(obj)
  File "C:\Users\Utilisateur\Documents\Environments\monoi_django_virtualenv\lib\site-packages\django\core\signing.py", line 87, in dumps
    return json.dumps(obj, separators=(',', ':')).encode('latin-1')
  File "c:\users\utilisateur\appdata\local\programs\python\python39\lib\json\__init__.py", line 234, in dumps
    return cls(
  File "c:\users\utilisateur\appdata\local\programs\python\python39\lib\json\encoder.py", line 199, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "c:\users\utilisateur\appdata\local\programs\python\python39\lib\json\encoder.py", line 257, in iterencode
    return _iterencode(o, 0)
  File "c:\users\utilisateur\appdata\local\programs\python\python39\lib\json\encoder.py", line 179, in default
    raise TypeError(f'Object of type {o.__class__.__name__} '

Exception Type: TypeError at /basket/
Exception Value: Object of type Product is not JSON serializable