python - Custom BaseInlineFormSet not saving -

i have subclassed baseinlineformset. i've overridden save() method, , inside it, first call super save method instances, like:

def save(self, convenient_attribute=none, commit=true, *args, **kwargs):     instances = super(custombasemodelformset, self).save(commit=false)     instance in instances:         # each instance         if commit:              instance.save()     return instances 

from view:

formset.save(convenient_attribute=some_object)

if check forms in formset var,it bound , valid. seems fine, the formset instances don't saved in db!

i've found when call superclass save(), var instances empty list. there's no instances commit. why don't them?