Django AttributeError: Form object has no attribute '_errors'

问题

I'm overriding the init method in my form andthis is now returning an error 'TransactionForm' object has no attribute '_errors'.

I would expect this to work because I've included super in my init, however perhaps I don't understand how to use this correctly. An explanation would be appreciated. What do I need to do to get form.errors working?

Full traceback

Traceback:

File "C:\Program Files\Python36\lib\site-packages\django\core\handlers\exception.py" in inner 35. response = get_response(request)

File "C:\Program Files\Python36\lib\site-packages\django\core\handlers\base.py" in _get_response 128. response = self.process_exception_by_middleware(e, request)

File "C:\Program Files\Python36\lib\site-packages\django\core\handlers\base.py" in _get_response 126. response = wrapped_callback(request, *callback_args, **callback_kwargs)

File "C:\py\portfolio-project\myportfolio\views.py" in add_transaction 136. return render(request, 'myportfolio/add_transaction.html', {'form': form})

File "C:\Program Files\Python36\lib\site-packages\django\shortcuts.py" in render 36. content = loader.render_to_string(template_name, context, request, using=using)

File "C:\Program Files\Python36\lib\site-packages\django\template\loader.py" in render_to_string 62. return template.render(context, request)

File "C:\Program Files\Python36\lib\site-packages\django\template\backends\django.py" in render 61. return self.template.render(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in render 175. return self._render(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in _render 167. return self.nodelist.render(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in render 943. bit = node.render_annotated(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in render_annotated 910. return self.render(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\loader_tags.py" in render 155. return compiled_parent._render(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in _render 167. return self.nodelist.render(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in render 943. bit = node.render_annotated(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in render_annotated 910. return self.render(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\loader_tags.py" in render 155. return compiled_parent._render(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in _render 167. return self.nodelist.render(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in render 943. bit = node.render_annotated(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in render_annotated 910. return self.render(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\loader_tags.py" in render 67. result = block.nodelist.render(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in render 943. bit = node.render_annotated(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in render_annotated 910. return self.render(context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in render 999. return render_value_in_context(output, context)

File "C:\Program Files\Python36\lib\site-packages\django\template\base.py" in render_value_in_context 978. value = str(value)

File "C:\Program Files\Python36\lib\site-packages\django\utils\html.py" in 371. klass.str = lambda self: mark_safe(klass_str(self))

File "C:\Program Files\Python36\lib\site-packages\django\forms\forms.py" in str 136. return self.as_table()

File "C:\Program Files\Python36\lib\site-packages\django\forms\forms.py" in as_table 279. errors_on_separate_row=False)

File "C:\Program Files\Python36\lib\site-packages\django\forms\forms.py" in _html_output 196. top_errors = self.non_field_errors() # Errors that should be displayed above all fields.

File "C:\Program Files\Python36\lib\site-packages\django\forms\forms.py" in non_field_errors 305. return self.errors.get(NON_FIELD_ERRORS, self.error_class(error_class='nonfield'))

File "C:\Program Files\Python36\lib\site-packages\django\forms\forms.py" in errors 173. if self._errors is None:

Exception Type: AttributeError at /myportfolio/add_transaction/ Exception Value: 'TransactionForm' object has no attribute '_errors'

forms

class TransactionForm(forms.ModelForm):     
    CHOICES = ((1, 'Buy'), (2, 'Sell'),)

    coin = forms.ModelChoiceField(queryset = Coin.objects.all()) 
    buysell = forms.ChoiceField(choices = CHOICES)

    field_order = ['buysell', 'coin', 'amount', 'trade_price']

    class Meta:
        model = Transactions
        fields = {'buysell', 'coin', 'amount', 'trade_price'}

    def __init__(self, coin_price = None, user = None, *args, **kwargs):

        if user:
            self.user = user
            qs_coin = Portfolio.objects.filter(user = self.user).values('coin').distinct()
            super(TransactionForm, self).__init__(self.user, *args, **kwargs)
            self.fields['coin'].queryset = qs_coin

        if coin_price:
            self.coin_price = coin_price
            super(TransactionForm, self).__init__(self.user, self.coin_price, *args, **kwargs)
            self.fields['price'] = self.coin_price

Views

def add_transaction(request):
    print(request.method)
    print("test1")

    print(request.GET)

    if request.method == "GET":
        if request.is_ajax():
            print("ajax test")

            data = {
                'test': "test1"
            }

            form = TransactionForm(request.GET, user = request.user, coin_price = GetCoin("Bitcoin").price)

            return JsonResponse(data)


    form = TransactionForm()
    if request.method == "POST":
        print("test2")
        form = TransactionForm(request.POST)
        if form.is_valid():
            print("test3")
            obj = form.save(commit = False)
            obj.user = request.user
            obj.save()
            return HttpResponseRedirect('/myportfolio/')
        else: 
            print(form.errors)

    return render(request, 'myportfolio/add_transaction.html', {'form': form})

回答1:

Form's superclass __init__ method not called if coin_price and user not provided. That's why such form's attributes as _errors was not created. You need to rewrite form's __init__ like this:

def __init__(self, coin_price = None, user = None, *args, **kwargs):
        super(TransactionForm, self).__init__(*args, **kwargs)
        if user:
            self.user = user
            qs_coin = Portfolio.objects.filter(user = self.user).values('coin').distinct()
            self.fields['coin'].queryset = qs_coin

        if coin_price:
            self.coin_price = coin_price
            self.fields['price'] = self.coin_price

To make super.__init__() called in any cases.

来源：https://stackoverflow.com/questions/50407569/django-attributeerror-form-object-has-no-attribute-errors