ManyToMany does not save to db Django - django

Question

I have a ManytoMany field and the results of the CheckboxSelectMultiple don't get saved in the db and i don't understand why. It must be really simple but...
Here's the code:
models.py
class Person(models.Model):
last_name = models.CharField(max_length = 50)
first_name = models.CharField(max_length = 50)
def __str__(self):
return self.last_name +" "+self.first_name
class Event(models.Model):
owner = models.ForeignKey(User, on_delete=models.SET_NULL, null = True)
person = models.ManyToManyField(Person)
forms.py
class EventForm(forms.ModelForm):
def __init__(self, *args, **kwargs):
self.user = kwargs.get('user',None)
#self.user = kwargs.pop('user',None)
super(EventForm, self).__init__(*args, **kwargs)
self.helper = FormHelper()
self.helper.form_method = 'POST'
#self.helper.form_action = reverse_lazy('simpleuser')
self.helper.add_input(Submit('submit', 'Submit', css_class='btn-success'))
class Meta:
model = Event
fields = ['person']
widgets ={
'person': forms.CheckboxSelectMultiple,
}
views.py
def uploadevent(request):
if request.method == "POST":
form =EventForm(request.POST)
if form.is_valid():
event = form.save(commit=False)
event.owner = request.user
event.save()
else:
form = EventForm()
return render...

Answer 1

See the response on this stackoverflow question: Saving Many To Many data via a modelform in Django
Quoting the OP:
When using commit=False, you have to call save_m2m()
m2m relationships require the parent object to be saved first, which
you are not doing by using commit=False
Just add this line below event.save()
if form.is_valid():
event = form.save(commit=False)
event.owner = request.user
event.save()
form.save_m2m()
Ref: https://docs.djangoproject.com/en/2.0/topics/forms/modelforms/#the-save-method

Answer 2

To save manytomany you should call save_m2m() when using commit=False (check details here):
if form.is_valid():
event = form.save(commit=False)
event.owner = request.user
event.save()
form.save_m2m()