Django UpdateView "init() takes at least 2 arguments (1 given)"

Question

My UpdateView to edit a Task was working fine until I filtered the foreign key field "Event" in forms.py (to make sure that users can only associate a task to an event belonging to them). Now it throws the

__init__() takes at least 2 arguments (1 given)

error when I try to edit a task. Please help.

Models.py

class Event(models.Model):
    host = models.ForeignKey('auth.User')
    title = models.CharField(max_length=70)
    description = models.TextField(max_length=200)
    venue = models.CharField(max_length=70, blank=True, null=True)
    date = models.DateField(blank=True, null=True, verbose_name="Date (DD/MM/YYYY)")
    category = models.CharField(max_length=3, choices=event_cat)

    def __unicode__(self):
            return self.title

class Task(models.Model):
    host = models.ForeignKey('auth.User')
    title = models.CharField(max_length=70)
    description = models.TextField(max_length=200)
    event = models.ForeignKey(Event)
    due_date = models.DateField(verbose_name="Date Due (DD/MM/YYYY, eg 31/12/2016)")
    due_time = models.TimeField(verbose_name="Time Due (HH:MM 24 hour format, e.g 14:30")
    status = models.CharField(max_length=3, choices=task_status)

    def __unicode__(self):
            return self.title

Forms.py

task_status = (  
    ('Pen', 'Pending'),
    ('Pro', 'In Progress'),
    ('Com', 'Completed'),
    ('Ove', 'Overdue'),
)

class TaskForm(forms.ModelForm):

    status = forms.ChoiceField(choices=task_status)

    class Meta:
        model = Task
        fields = ('title','description','event','due_date','due_time','status')

    def __init__(self, host, *args, **kwargs):
            super(TaskForm, self).__init__(*args, **kwargs)
            self.fields['event'].queryset = Event.objects.filter(host=host)
            self.fields['due_date'].widget.format = '%d/%m/%Y'
            self.fields['due_date'].input_formats = ['%d/%m/%Y']

            def get_date(self):
                return self.modified.date()

    def clean_date(self):
            date = self.cleaned_data['due_date']
            if date:
                if date < datetime.date.today():
                    raise forms.ValidationError("The date cannot be in the past!")
                return date
            else:
                return date

Views.py

class edit_task(UpdateView):
    model = Task
    form_class = TaskForm
    success_url = reverse_lazy('tasks')
    template_name = 'dashboard/task_edit.html'

    def get(self, request, *args, **kwargs):
        self.object = self.get_object()
        return super(edit_task, self).get(request, *args, **kwargs)

    def post(self, request, *args, **kwargs):
        self.object = self.get_object()
        return super(edit_task, self).post(request, *args, **kwargs)

Urls.py

url(r'^dashboard/tasks/edit/(?P<pk>\d+)/$', views.edit_task.as_view(), name='edit_task')

Traceback:

File ".../lib/python2.7/site-packages/django/core/handlers/base.py" in get_response
  132.                     response = wrapped_callback(request, *callback_args, **callback_kwargs)
File ".../lib/python2.7/site-packages/django/views/generic/base.py" in view
  71.             return self.dispatch(request, *args, **kwargs)
File ".../lib/python2.7/site-packages/django/views/generic/base.py" in dispatch
  89.         return handler(request, *args, **kwargs)
File ".../views.py" in get
  149.         return super(edit_task, self).get(request, *args, **kwargs)
File ".../lib/python2.7/site-packages/django/views/generic/edit.py" in get
  268.         return super(BaseUpdateView, self).get(request, *args, **kwargs)
File ".../lib/python2.7/site-packages/django/views/generic/edit.py" in get
  205.         form = self.get_form()
File ".../lib/python2.7/site-packages/django/views/generic/edit.py" in get_form
  74.         return form_class(**self.get_form_kwargs())

Exception Type: TypeError at /dashboard/tasks/edit/7/
Exception Value: __init__() takes at least 2 arguments (1 given)

you need to override the `get_form_kwargs` method of the view to supply the `host` kwarg that you've added to the `__init__` method of the form class — Anentropic, Feb 17 '16 at 09:39
who is going to pass the `host` parameter to the form's `__init__`? surely not the `get_form` method, which does `...return form_class(**self.get_form_kwargs())` as you can see [here](http://ccbv.co.uk/projects/Django/1.9/django.views.generic.edit/UpdateView/) — Pynchia, Feb 17 '16 at 09:41
I think better `host = kwargs.pop('host')` rather than passing `host` explicitly. check http://stackoverflow.com/questions/5806224/sending-request-user-object-to-modelform-from-class-based-generic-view-in-django — Ahmed Hosny, Feb 17 '16 at 09:42
where does the `host` parameter come from? URL parameter? I cannot see it in the url pattern (only `pk` is present) — Pynchia, Feb 17 '16 at 09:46

Alasdair · Accepted Answer · 2016-02-17T14:35:26.113

1

The Task model has a foreign key to host. Since this is an update view, I don't think you actually need to pass the host to the model form's __init__ method. Use self.instance.host instead.

class TaskForm(forms.ModelForm):
    ...
    def __init__(self, *args, **kwargs):
        super(TaskForm, self).__init__(*args, **kwargs)
        self.fields['event'].queryset = Event.objects.filter(host=self.instance.host)
        ...

If you really do need to pass host to the model form, then you can override get_form_kwargs. Since host seems to be the logged in user, you would do:

class EditTask(UpdateView):  
    # since this is a class, EditTask is a better name than edit_task
    ...
    def get_form_kwargs(self):
        kwargs = super(EditTask, self).get_form_kwargs()
        kwargs['host'] = self.request.user
        return kwargs

edited Feb 17 '16 at 14:35

answered Feb 17 '16 at 10:20

Alasdair

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Added this to view: `def get_form_kwargs(self, **kwargs): kwargs = super(EditTask, self).get_form_kwargs(**kwargs) kwargs['host'] = self.request.user return kwargs` – mn2022 Feb 17 '16 at 14:25
My example was missing `return kwargs`, I've fixed it now. You shouldn't add `**kwargs` to the function signature, or pass kwargs to the `super()` call. – Alasdair Feb 17 '16 at 14:36

Django UpdateView "__init__() takes at least 2 arguments (1 given)"

1 Answers1

Django UpdateView "init() takes at least 2 arguments (1 given)"