只有一个 CharField 的 Django 模型无法序列化为 JSON

Question

我有一个非常基础的“地点”模型：

from django.db import models

class Place(models.Model):
    name = models.CharField(max_length=100)

    def __unicode__(self):
        return self.name

我正在尝试使用这个应用来进行评论：https://github.com/diefenbach/django-reviews

当我试图给某个地点对象添加评论时，在应用的视图中https://github.com/diefenbach/django-reviews/blob/master/reviews/views.py，它会进入“保存”方法，并且确实在数据库中保存了一条记录。但是，它却抛出了一个类型错误（TypeError）：

Environment:


Request Method: POST
Request URL: http://ec2-54-77-118-44.eu-west-1.compute.amazonaws.com:5000/reviews/add/11/1

Django Version: 1.6.5
Python Version: 2.7.6
Installed Applications:
('django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'south',
 'places',
 'reviews')
Installed Middleware:
('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/ubuntu/webapps/local/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  199.                 response = middleware_method(request, response)
File "/home/ubuntu/webapps/local/lib/python2.7/site-packages/django/contrib/sessions/middleware.py" in process_response
  38.                     request.session.save()
File "/home/ubuntu/webapps/local/lib/python2.7/site-packages/django/contrib/sessions/backends/db.py" in save
  57.             session_data=self.encode(self._get_session(no_load=must_create)),
File "/home/ubuntu/webapps/local/lib/python2.7/site-packages/django/contrib/sessions/backends/base.py" in encode
  87.         serialized = self.serializer().dumps(session_dict)
File "/home/ubuntu/webapps/local/lib/python2.7/site-packages/django/core/signing.py" in dumps
  88.         return json.dumps(obj, separators=(',', ':')).encode('latin-1')
File "/usr/lib/python2.7/json/__init__.py" in dumps
  250.         sort_keys=sort_keys, **kw).encode(obj)
File "/usr/lib/python2.7/json/encoder.py" in encode
  207.         chunks = self.iterencode(o, _one_shot=True)
File "/usr/lib/python2.7/json/encoder.py" in iterencode
  270.         return _iterencode(o, 0)
File "/usr/lib/python2.7/json/encoder.py" in default
  184.         raise TypeError(repr(o) + " is not JSON serializable")

Exception Type: TypeError at /reviews/add/11/1
Exception Value: <Place: Teteria India> is not JSON serializable

我不明白为什么会出现这个错误，因为我还没有使用任何AJAX或JSON，尽我所能看到的，评论应用的视图也没有使用。这和表单有关系吗？

而且，怎么会一个只有一个字符字段（CharField）的模型不能被JSON序列化呢？我需要提供序列化吗？

谢谢！

Answer 1

在第148行，它把object存储在会话中。

request.session["last-rated-object"] = object

然后它会重定向到reviews_thank_you的视图。

def thank_you(request, template_name="reviews/thank_you.html"):
    """Displays a thank you page.
    """
    if request.session.has_key("last-rated-object"):
        object = request.session.get("last-rated-object")
        del request.session["last-rated-object"]
    else:
        object = None

    return render_to_response(template_name, RequestContext(request, {
        "object" : object,
    }))

它在没有序列化object的情况下返回了这个对象，我觉得这就是问题所在。你能修改那个视图，让它返回一个序列化版本的object吗？