Question

I am making an Ajax request into views as follows:

def all_json_models(request):
    data = {}
    try:

    isp = request.GET['status']
    present_isp =  Priority.objects.filter(ispname = isp)
    isp_count = MultiWAN.objects.all()

  #  data['latest_no_rules']  =   latest_no_rules
    #data['present_isp']  = present_isp
    data['isp_count'] = isp_count

    return HttpResponse(simplejson.dumps(data))   

my models.py is like

class MultiWAN(models.Model):

    isp_name = models.CharField(max_length=10)
    description  = models.TextField(null=True)
    ip_address   = models.IPAddressField(null=True)
    subnet       = models.IPAddressField(null=True)
    gateway      = models.IPAddressField(null=True)
    nameserver   = models.ForeignKey('NameServer')
    weight       = models.IntegerField(null=False)
    interface    = models.CharField(max_length=5) 
    def __unicode__(self):
        """
        This function is to return the values we required.
        Arguments:
        - `self`:
        """
      #  return u'%s ' % (self.isp_name)


class NameServer(models.Model):
    """  A Isp can have more than one nameserver so far we are declearing a seperate table 
    """         
    name = models.IPAddressField(null=False)    




class Priority(models.Model):  
    priority =  models.IntegerField(null = True)
    ispname = models.ForeignKey('MultiWAN')
    rule = models.CharField(max_length=5,null=False)
    From  =    models.IPAddressField(null=True)
    To = models.IPAddressField(null=True)
    def __unicode__(self):
                      return u'%s ' % (self.priority)

while making request i am getting the error:

"coercing to Unicode: need string or buffer, NoneType found"

What i am doing wrong here?

Answer 1

It’s hard to tell without the full traceback (because it gives information about where in you code the exception is thrown).

The error message “coercing to Unicode: need string or buffer, NoneType found” means that, at some point, django tried to convert something to unicode and expected a string, but received None. This means that either you call a function passing None instead of a string, or one of you methods returns None instead of a string.

In the code you showed us, MultiWAN.__unicode__ seems ill-defined. Maybe the error stems from this ?