overriding __init__ in forms.ModelForm is erroring with POST method

[Mayank Tripathi]

Hi All,

I am working on small hands-on project.. and having an issue when calling the POST method with form.py overriding __init__.

Below is the code.

Here i have two models.. one is Category and another is SubCategory.

For SubCategory i have created form "SubCategoryFormv2" in forms.py... where i am checking if categoryid is passed then pre-select that Category, else display all Category for selection.

On submit the form from html... i am getting TypeError. (full error is displayed below)

Please help... What i could identify is with the POST method, when the statement form = SubCategoryFormv2(request.POST) is executed, it is expecting some id.. not sure what is this id.

# models.py

------------------------

class SubCategory(models.Model) : 

category  = models.ForeignKey(Category, null = True, on_delete = models.SET_NULL)

name  = models.CharField(max_length = 200, null = True)

dateCreated  = models.DateTimeField(default = timezone.now)

createdBy  = models.ForeignKey(User, on_delete = models.PROTECT )

# forms.py

--------------------------

class SubCategoryFormv2(forms.ModelForm): 

class Meta:

model = SubCategory

fields = '__all__'

widgets = {'dateCreated' : DateInput()}

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

super(SubCategoryFormv2, self).__init__(*args, **kwargs)

if categoryid is not None:

self.fields['category'] = forms.ModelChoiceField(initial=categoryid, queryset=Category.objects.filter(id=categoryid))

# views.py

--------------------------------

def createSubCategoryV2(request, categoryid=None):

context = {

'title':'Add SubCategory'

}

if request.method =='POST':

print('POST METHOD')

form = SubCategoryFormv2(request.POST)

print('POST METHOD - SubCategoryFormv2 called')

if form.is_valid():

ins = form.save(commit=True)

print('Inside for form validation')

messages.success(request, f'SubCategory added Successfully')

return redirect('listsubcategory')

else: # for GET method.

print('GET METHOD')

form = SubCategoryFormv2(categoryid)

context["form"]= form

return render(request, 'DailyBudget/subcategory_form.html', context)

Error : 

Exception Value:	Field 'id' expected a number but got <QueryDict: {'csrfmiddlewaretoken': ['XXXXXXXXXX'], 'category': ['12'], 'name': ['Test Data'], 'dateCreated': ['2020-05-02'], 'initial-dateCreated': ['2020-05-02 04:11:38'], 'createdBy': ['1']}>.