def METHOD_NAME(self, param_field_name, param_field_value):
    param_name, field_name = param_field_name
    param_value, field_value = param_field_value
    self.form_data[param_name] = param_value
    self.cleaned_data[param_name] = field_value
    if field_value is not None:
        self.cleaned_data['filter_'] = {field_name: field_value}
    self.assert_valid(self.cleaned_data)