modelcluster/forms.py
def validate_unique(self):
        '''This clean method will check for unique_together condition'''
        # Collect unique_checks and to run from all the forms.
        all_unique_checks = set()
        all_date_checks = set()
        forms_to_delete = self.deleted_forms
        valid_forms = [form for form in self.forms if form.is_valid() and form not in forms_to_delete]
        for form in valid_forms:
            unique_checks, date_checks = form.instance._get_unique_checks()
            all_unique_checks.update(unique_checks)
            all_date_checks.update(date_checks)

        errors = []
        # Do each of the unique checks (unique and unique_together)
        for uclass, unique_check in all_unique_checks:
            seen_data = set()
            for form in valid_forms:
                # Get the data for the set of fields that must be unique among the forms.
                row_data = (
                    field if field in self.unique_fields else form.cleaned_data[field]
                    for field in unique_check if field in form.cleaned_data
                )
                # Reduce Model instances to their primary key values
                row_data = tuple(d._get_pk_val() if hasattr(d, '_get_pk_val') else d
                                 for d in row_data)
                if row_data and None not in row_data:
                    # if we've already seen it then we have a uniqueness failure
                    if row_data in seen_data:
                        # poke error messages into the right places and mark
                        # the form as invalid
                        errors.append(self.get_unique_error_message(unique_check))
                        form._errors[NON_FIELD_ERRORS] = self.error_class([self.get_form_error()])
                        # remove the data from the cleaned_data dict since it was invalid
                        for field in unique_check:
                            if field in form.cleaned_data:
                                del form.cleaned_data[field]
                    # mark the data as seen
                    seen_data.add(row_data)

        if errors:
            raise ValidationError(errors)
def validate_unique(self):
        '''This clean method will check for unique_together condition'''
        # Collect unique_checks and to run from all the forms.
        all_unique_checks = set()
        all_date_checks = set()
        forms_to_delete = self.deleted_forms
        valid_forms = [form for form in self.forms if form.is_valid() and form not in forms_to_delete]
        for form in valid_forms:
            unique_checks, date_checks = form.instance._get_unique_checks()
            all_unique_checks.update(unique_checks)
            all_date_checks.update(date_checks)

        errors = []
        # Do each of the unique checks (unique and unique_together)
        for uclass, unique_check in all_unique_checks:
            seen_data = set()
            for form in valid_forms:
                # Get the data for the set of fields that must be unique among the forms.
                row_data = (
                    field if field in self.unique_fields else form.cleaned_data[field]
                    for field in unique_check if field in form.cleaned_data
                )
                # Reduce Model instances to their primary key values
                row_data = tuple(d._get_pk_val() if hasattr(d, '_get_pk_val') else d
                                 for d in row_data)
                if row_data and None not in row_data:
                    # if we've already seen it then we have a uniqueness failure
                    if row_data in seen_data:
                        # poke error messages into the right places and mark
                        # the form as invalid
                        errors.append(self.get_unique_error_message(unique_check))
                        form._errors[NON_FIELD_ERRORS] = self.error_class([self.get_form_error()])
                        # remove the data from the cleaned_data dict since it was invalid
                        for field in unique_check:
                            if field in form.cleaned_data:
                                del form.cleaned_data[field]
                    # mark the data as seen
                    seen_data.add(row_data)

        if errors:
            raise ValidationError(errors)
This clean method will check for unique_together condition