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DJANGO - Minimum required formset
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from django import forms | |
# how to use: | |
# Formset = inlineformset_factory(ParentModel, Model, ModelForm, \ | |
# formset=MinimumRequiredFormSet, extra=1, can_delete=True) | |
# instance = Formset(request.POST or None, instance=obj, prefix="prefix_form", \ | |
# minimum_forms=2, minimum_forms_message="At least two items are required.",) | |
class MinimumRequiredFormSet(forms.models.BaseInlineFormSet): | |
""" | |
Inline formset that enforces a minimum number of non-deleted forms | |
that are not empty | |
""" | |
default_minimum_forms_message = "At least %s set%s of data is required" | |
def __init__(self, *args, **kwargs): | |
self.minimum_forms = kwargs.pop('minimum_forms', 0) | |
minimum_forms_message = kwargs.pop('minimum_forms_message', None) | |
if minimum_forms_message: | |
self.minimum_forms_message = minimum_forms_message | |
else: | |
self.minimum_forms_message = \ | |
self.default_minimum_forms_message % ( | |
self.minimum_forms, | |
'' if self.minimum_forms == 1 else 's' | |
) | |
super(MinimumRequiredFormSet, self).__init__(*args, **kwargs) | |
def clean(self): | |
non_deleted_forms = self.total_form_count() | |
non_empty_forms = 0 | |
for i in xrange(0, self.total_form_count()): | |
form = self.forms[i] | |
if self.can_delete and self._should_delete_form(form): | |
non_deleted_forms -= 1 | |
elif not (form.instance.id is None and not form.has_changed()): | |
non_empty_forms += 1 | |
if ( | |
non_deleted_forms < self.minimum_forms | |
or non_empty_forms < self.minimum_forms | |
): | |
raise forms.ValidationError(self.minimum_forms_message) |
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