Django: Initializing a FormSet of custom forms with instances - django

Question

Given the following models:
class Graph(models.Model):
owner = models.ForeignKey(User)
def __unicode__(self):
return u'%d' % self.id
class Point(models.Model):
graph = models.ForeignKey(Graph)
date = models.DateField(primary_key = True)
abs = models.FloatField(null = True)
avg = models.FloatField(null = True)
def __unicode__(self):
return u'%s' % self.date
I am trying to create a form for editing lists of Points.
The HTML input tags require additional attributes to be set, so I am using the following custom form:
class PointForm(forms.ModelForm):
graph = forms.ModelChoiceField(queryset = Graph.objects.all(),
widget = forms.HiddenInput())
date = forms.DateField(widget = forms.HiddenInput(), label = 'date')
abs = forms.FloatField(widget = forms.TextInput(
attrs = {'class': 'abs-field'}),
required = False)
class Meta:
model = Point
fields = ('graph', 'date', 'abs') # Other fields are not edited.
def pretty_date(self):
return self.data.strftime('%B')
At this point I do not know how to pass instances of the Point class to a FormSet:
def edit(request):
PointFormSet = forms.formsets.formset_factory(PointForm, extra = 0)
if request.method == 'POST':
return
# Receive 3 points to edit from the database.
graph, res = Graph.objects.get_or_create(id = 1)
one_day = datetime.timedelta(days = 1)
today = datetime.date.today()
do_edit = []
for date in [today - (x * one_day) for x in range(3)]:
point, res = Point.objects.get_or_create(graph = graph, date = date)
do_edit.append(point)
formset = PointFormSet(????) # How is this initialized with the points?
I found a hack that somewhat works, but it leads to errors later on when trying to process the resulting POST data:
do_edit = []
for date in [today - (x * one_day) for x in range(3)]:
point, res = Point.objects.get_or_create(graph = graph, date = date)
data = point.__dict__.copy()
data['graph'] = graph
do_edit.append(data)
formset = PointFormSet(initial = do_edit)
How is this done correctly?
For the reference, my template looks like this:
<form action="" method="post">
{{ formset.management_form }}
<table>
<tbody>
{% for form in formset.forms %}
<tr>
<td>{{ form.graph }} {{ form.date }} {{ form.pretty_date }}:</td>
<td width="100%">{{ form.abs }}</td>
</tr>
{% endfor %}
</tbody>
</table>
</form>

Answer 1

The trick is to use a "ModelFormset" instead of just a formset since they allow initialization with a queryset. The docs are here, what you do is provide a form=* when creating the model formset and queryset=* when your instantiating the formset. The form=* arguement is not well documented (had to dig around in the code a little to make sure it is actually there).
def edit(request):
PointFormSet = modelformset_factory(Point, form = PointForm)
qset = Point.objects.all() #or however your getting your Points to modify
formset = PointFormset(queryset = qset)
if request.method == 'POST':
#deal with posting the data
formset = PointFormset(request.POST)
if formset.is_valid():
#if it is not valid then the "errors" will fall through and be returned
formset.save()
return #to your redirect
context_dict = {'formset':formset,
#other context info
}
return render_to_response('your_template.html', context_dict)
So the code walks through easily. If the request is a GET then the instantiated form is returned to the user. If the request is a POST and the form is not .is_valid() then the errors "fall through" and are returned in the same template. If the request is a POST and the data is valid then the formset is saved.
Hope that helps.
-Will

Answer 2

If you only have one possible value which you want to set, or perhaps a closed of values, it is possible to set them after the user POSTS the data to your server using commit=False
Please consider the following code:
class UserReferralView(View):
ReferralFormSet = modelformset_factory(ReferralCode,
form=ReferralTokenForm, extra=1)
def get(self, request):
pass
def post(self, request):
referral_formset = UserUpdateView.ReferralFormSet(request.POST)
if referral_formset.is_valid():
instances = referral_formset.save(commit=False)
for instance in instances:
instance.user = request.user
instance.save()
return redirect(reverse('referrals.success_view'))
else:
return redirect(reverse('referrals.failure_view'))