If I create a sale order and the forecasted quantity for a product is 0, I don't get an error, but the value simply becomes negative. I tried to do it the same way as it is done in MrpProduction, but I can't do it. I found the module "Sale Quantity Non-zero" on the Internet, but it is written for version 8 of odoo, and I am using version 14.

Sale Quantity Non-zero realization:

@api.one

    @api.constrains('product_uom_qty', 'product_uos_qty')

    def constraint_qty(self):

        if float_compare(0, self.product_uom_qty, precision_digits=2) >= 0:

            raise exceptions.ValidationError(

                _('Product quantity cannot be less than one!')

            )

        if float_compare(0, self.product_uos_qty, precision_digits=2) >= 0:

            raise exceptions.ValidationError(

                _('Product UoS quantity cannot be less than one!')

            )

My realizations (but its didn work):

_inherit = ['product.product']

@api.onchange('virtual_available')
def constraint_qty(self):

    if float_is_zero(self.virtual_available, precision_digits=2):
        raise UserError(
            _('Product quantity cannot be less than one!')
        )

MrpProduction realization:

def _pre_button_mark_done(self):
    productions_to_immediate = self._check_immediate()
    if productions_to_immediate:
        return productions_to_immediate._action_generate_immediate_wizard()

    for production in self:
        if float_is_zero(production.qty_producing, precision_rounding=production.product_uom_id.rounding):
            raise UserError(_('The quantity to produce must be positive!'))
        if not any(production.move_raw_ids.mapped('quantity_done')):
            raise UserError(_("You must indicate a non-zero amount consumed for at least one of your components"))

    consumption_issues = self._get_consumption_issues()
    if consumption_issues:
        return self._action_generate_consumption_wizard(consumption_issues)

    quantity_issues = self._get_quantity_produced_issues()
    if quantity_issues:
        return self._action_generate_backorder_wizard(quantity_issues)
    return True