python之TypeError 强制转换为 Unicode : need string or buffer

在一个 Django 项目中，我试图将 url 传递给一个想要的实例。评论应用于需求。我一直试图找出这个错误，但被难住了。

这个函数:

     def comment_email(request, comment, **kwargs): 
         want = get_object_or_404(Want, id=comment.object_pk) 
         url = want.get_absolute_url 
         print url 

正在抛出这个错误

Environment: 
 
Request Method: POST 
Request URL: http://localhost:8000/comments/post/ 
Django Version: 1.2.3 
Python Version: 2.7.0 
Installed Applications: 
['django.contrib.auth', 
 'django.contrib.contenttypes', 
 'django.contrib.sessions', 
 'django.contrib.sites', 
 'django.contrib.messages', 
 'django.contrib.admin', 
 'django.contrib.comments', 
 'django.contrib.markup', 
 'src', 
 'lib.tagging', 
 'lib.markdown', 
 'lib.avatar', 
 'ajaxcomments', 
 'south'] 
Installed Middleware: 
('django.middleware.common.CommonMiddleware', 
 'django.contrib.sessions.middleware.SessionMiddleware', 
 'django.middleware.csrf.CsrfViewMiddleware', 
 'django.contrib.auth.middleware.AuthenticationMiddleware', 
 'django.contrib.messages.middleware.MessageMiddleware') 
 
 
Traceback: 
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/core/handlers/base.py" in get_response 
  100.                     response = callback(request, *callback_args, **callback_kwargs) 
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/ajaxcomments/utils.py" in wrapped 
  57.         return func(*args, **kwargs) 
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/utils/decorators.py" in _wrapped_view 
  76.                     response = view_func(request, *args, **kwargs) 
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/views/decorators/http.py" in inner 
  37.             return func(request, *args, **kwargs) 
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/contrib/comments/views/comments.py" in post_comment 
  127.         request = request 
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/dispatch/dispatcher.py" in send 
  162.             response = receiver(signal=self, sender=sender, **named) 
File "/Users/emilepetrone/code/apprentice2/src/utils.py" in comment_email 
  24.   print url 
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/django/db/models/base.py" in __repr__ 
  344.             u = unicode(self) 
 
Exception Type: TypeError at /comments/post/ 
Exception Value: coercing to Unicode: need string or buffer, Want found 

这是旺旺模型:

     class Want(models.Model): 
 
       pub_date =         models.DateTimeField(default=datetime.now,auto_now_add=True,db_index=True) 
       body = models.TextField(default='',max_length=1000) 
       body_html = models.TextField(editable=False, blank=True) 
 
       #Metadata 
       mentee = models.ForeignKey(User) 
       points = models.IntegerField(default=3) 
       enable_comments = models.BooleanField(default=True) 
       featured = models.BooleanField(default=False) 
 
       #Tags 
       tags = TagField(help_text="Autocomplete") 
 
       def get_tags(self): 
         return Tag.objects.get_for_object(self)       
 
       class Meta: 
         ordering = ['-pub_date'] 
 
       def __unicode__(self): 
         return self 
 
       def save(self): 
         self.body_html = markdown(self.body) 
         super(Want, self).save() 
 
       def get_absolute_url(self): 
         return ( { 'object_id': self.id }) 
       get_absolute_url = models.permalink(get_absolute_url) 

感谢您的帮助!

请您参考如下方法:

我觉得问题是

def __unicode__(self): 
    return self 

它应该返回一个 unicode 字符串而不是一个“Want”实例。我不确定你想要什么——也许是“self.id”