嘗試更新模型對象時無法迭代「NoneType」類型的參數

Question

獲取錯誤Argument of type 'NoneType' is not iterable並找不到原因。

它發生在該行if model_form.is_valid():

Views.py

def update_model(request, pricemodel_id): 
    """ Update a part given its id. """ 
    pricemod = Part.objects.get(id=pricemodel_id) 
    if request.method == "POST": 
     print "post request" 
     model_form = priceform(request.POST, request.FILES, instance=pricemod) 
     model_form.is_update = True 
     if request.user == pricemod.adder: 
      #from ipdb import set_trace; set_trace() 
      if model_form.is_valid(): 

Forms.py

class priceform(ModelForm): 
# price Form: form associated to the Part model 
    def __init__(self, *args, **kwargs): 
     super(priceform, self).__init__(*args,**kwargs) 
     self.is_update=False 
     choices = UniPart.objects.all().values('manufacturer').distinct() 
    def clean(self): 
     if self.cleaned_data and 'modelname' not in self.cleaned_data: 
      raise forms.ValidationError("Some error message") 
      if not self.is_update: 
       return self.cleaned_data 
      return self.cleaned_data 
    class Meta: 
     model = Part 

Answer 1

看起來是因爲在你的清潔方法錯誤縮進。目前它不返回任何東西，即返回None，但必須返回self.cleaned_data。您所有的clean方法代碼都在if之下，這會引發異常。如果if不匹配，則返回None。

試試這個：

class priceform(ModelForm): 
    # ... 
    def clean(self): 
     if self.cleaned_data and 'modelname' not in self.cleaned_data: 
      raise forms.ValidationError("Some error message") 
     if not self.is_update: 
      return self.cleaned_data 
     return self.cleaned_data 

    # ...