Why is form.cleaned_data empty even though form.data has two keys?

Question

Django

Request processing: (on line pass len(form.data) = 2 and len(form.cleaned_data) = 0)

form = ReportPeriodSelectForm(request.GET)
my_bonuses = tree_node.get_invite_bonuses()

my_bonuses = sorted(my_bonuses, key=lambda x: x.line)
date_min = tree_node.contract_date
date_max = date.today()
if form.is_valid():
    pass
if 'date_min' in form.cleaned_data and form._cleaned_data['date_min']:
    date_min = form.cleaned_data['date_min']
if 'date_max' in form.cleaned_data and form.cleaned_data['date_max']:
    date_max = form.cleaned_data['date_max']
my_bonuses = filter(lambda x: date_max >= x.bonus_date >= date_min, my_bonuses)
total = sum([x.total for x in my_bonuses if not x.defaulter_invited])

The form:

class ReportPeriodSelectForm(forms.Form):
    date_min = forms.DateField(widget=widgets.DateInput(attrs={'class': 'form-control text-center',
                                                               'placeholder': 'с',
                                                               'name': 'date_min'}))
    date_max = forms.DateField(widget=widgets.DateInput(attrs={'class': 'form-control text-center',
                                                               'placeholder': 'по',
                                                               'name': 'date_max'}))

HTML:

<form action="/pyramid/profile/invite_bonuses/" class="form-horizontal form-bordered">
                <!-- Datepicker for Bootstrap (classes are initialized in js/app.js -> uiInit()), for extra usage examples you can check out http://eternicode.github.io/bootstrap-datepicker -->
                <fieldset>
                    <div class="form-group">
                        <label class="col-md-4 control-label" for="example-daterange1">Выберите диапазон дат:</label>

                        <div class="col-md-8">
                            <div class="input-group input-daterange" data-date-format="dd/mm/yyyy">
                                {{ form.date_min }}
                                <span class="input-group-addon"><i class="fa fa-angle-right"></i></span>
                                {{ form.date_max }}
                            </div>
                        </div>
                    </div>

                    <div class="form-group form-actions">
                        <div class="col-md-8 col-md-offset-4">
                            <input type="submit" value="Выбрать" class="btn btn-sm btn-primary"/>
                            <input type="reset" value="Очистить" class="btn btn-sm btn-warning"/>
                        </div>
                    </div>
                </fieldset>

            </form>

Answer 1

form.is_valid()
if everything is fine, form.cleaned_data will appear
Proof: https://docs.djangoproject.com/en/1.7/topics/forms...
"A Form instance has an is_valid() method, which runs validation routines for all its fields.When this method is called, if all fields contain valid data, it will:
return True
place the form's data in its cleaned_data attribute."
UDP:
didn't notice that is_valid is already being called. But it's better to do otherwise

if form.is_valid():
  date_min = form.cleaned_data['date_min']
  date_max = form.cleaned_data['date_max']
else:
  # что-то делать, если данные невалидны