django form field validation using parameter from URL

Question

I have a visit-create class based on a CreateView. It accesses the organization from the URL, so it's passed in as a keyword arg.

class VisitCreate(LoginRequiredMixin, UserOrgRequiredMixin, CreateView):
    model = models.Visit
    form_class = VisitCreateForm
    # template_name is "visit_form.html" from CreateView

    def form_valid(self, form):
        # get the patient for this visit
        patient = models.Patient.get_by_pk(self.kwargs['patientId'])
        if not patient or patient.organization.name != self.kwargs['orgStr']:
            raise SuspiciousOperation('Patient does not exist')

I want to write a form field validator that checks something about the visit, but it needs the orgStr. Here is the current form field validator, but it can't get the orgStr:

class VisitCreateForm(ModelForm):
    class Meta:
        model = models.Visit
        ...
    # Allow only one visit per day
    def clean_visit_date(self):
        visit_date = self.cleaned_data['visit_date']
        if models.Visit.get_visits(visit_date, visit_date, self.kwargs['orgStr']):
            raise ValidationError('There is already a visit on this date')

How do I mark a field error on visit_date? Either I have to pass orgStr to the form somehow, or mark the field error in VisitCreate.form_valid.

Please don't suggest adding the orgStr as a hidden field in the form. That seems crazy.

I would try to keep the validation in the form. You can add errors in the form_valid() method with form.add_error(...), but then you need to handle your invalid form (e.g. by returning self.form_invalid(...)), which complicates the flow of the code. — Alasdair
– Alasdair, Commented Apr 9, 2018 at 15:19

dfrankow · Accepted Answer · 2018-04-09 16:25:25Z

2

You can override the view's get_form_kwargs method to pass orgStr from the URL:

class VisitCreate(LoginRequiredMixin, UserOrgRequiredMixin, CreateView):
    def get_form_kwargs(self):
        kwargs = super(VisitCreate, self).get_form_kwargs()
        kwargs['orgStr'] = self.kwargs['orgStr']
        return kwargs

You then need to override the form's __init__ method to handle orgStr.

class VisitCreateForm(ModelForm):
    ...

    def __init__(self, *args, **kwargs):
        self.orgStr = kwargs.pop('orgStr')
        super(VisitCreateForm, self).__init__(*args, **kwargs)

    # You can now access `self.orgStr` in the `clean_visit_date` method.
    def clean_visit_date(self):
        visit_date = self.cleaned_data['visit_date']
        if models.Visit.get_visits(visit_date, visit_date, self.orgStr):
            raise ValidationError('There is already a visit on this date')

edited Apr 9, 2018 at 16:25

dfrankow

21.7k44 gold badges168 silver badges246 bronze badges

answered Apr 9, 2018 at 15:17

Alasdair

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1 Comment

dfrankow Over a year ago

You sir are a gentleman and a scholar. If only I could give you more than one upvote.

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