Django multiplechoicefield always renders None - django

Question

I made a multiplechoicefield form (to ask what category user wants to select), but i can't get the answer back...it always renders "None".
I added some 'print' in the code to be sure that it was the problem and it is.
I don't understand why.
forms.py:
class Category(forms.ModelForm):
class Meta:
model = Auctions
fields = ("category",)
#fields = ('category',)
#widgets = {'category' : forms.RadioSelect()}
catform = forms.MultipleChoiceField(choices=fields, widget=forms.CheckboxSelectMultiple())
models.py
'''
class Auctions(models.Model):
Category = [('FASHION', 'Fashion'),('TOYS','Toys'),('ELECTRONICS','Electronics'),('HOME','Home')]
ID_auction = models.AutoField(primary_key = True)
title = models.CharField(max_length = 80)
description = models.TextField()
startingbid = models.IntegerField()
image = models.URLField(blank = True)
category = models.CharField(max_length = 80, choices = Category)
author_id = models.ForeignKey(User,on_delete = models.CASCADE, related_name = "auteur")
highest_bid = models.IntegerField("Bid", blank = True, null = True)
buyer = models.ForeignKey(User, on_delete = models.CASCADE, related_name = "acheteur")
active = models.BooleanField(default=True)
'''
views.py
'''
def filter_cat(request):
if request.method == "POST":
form = Category(request.POST)
print(form)
if form.is_valid():
cat = form.cleaned_data.get("catform")
print(cat)
auctions = Auctions.objects.filter(category = cat)
return render(request, "auctions/index.html",{
'active_listing' : auctions, 'cat' : cat
})
else :
form = Category()
return render(request, "auctions/filter_cat.html",{'form' : form})
'''
when I select FASHION for example i get this on the terminal :
for print(form):
Category:
---------
Fashion
Toys
Electronics
Home
for print(cat):
None