I am working on CRUD application which helps to keep count of inventory.

I have a controller editDevice() that edit inventory card of device. Here I add an attribute “acts” which contains all previously created acts with this device. History of device acts displays on the html form. Method showActsByDevice() takes data from postgresql view. Respectively I made a controller updateDevice() where I handle DuplicateKeyException and return html form.

    @GetMapping("/{inventoryCard}/edit")
    public String editDevice(@PathVariable("inventoryCard") String inventoryCard, Model model){
        model.addAttribute("device", deviceDAO.showOne(inventoryCard));
        model.addAttribute("acts", actDAO.showActsByDevice(inventoryCard));
        return "property/edit_device.html";
    }

    @PatchMapping("/{inventoryCard}")
    public String updateDevice(@ModelAttribute("device") @Valid Device device,
                               BindingResult bindingResult,
                               @PathVariable("inventoryCard") String inventoryCard){
        try{
            deviceDAO.update(inventoryCard, device);
        } catch(DuplicateKeyException e){
            bindingResult.rejectValue("inventoryCard", "error.inventoryCard", "This inventory card already used");
        }
        if(bindingResult.hasErrors()){
            return "property/edit_device.html";
        }
        return "redirect:/device/show_all";
    }

But then I don’t have “acts” attribute in model and then I cannot show acts of device.

I have tried to use redirectAttributes but it’s not displaying error message and as I understand it, in this case I should not use it.

        if(bindingResult.hasErrors()){
            redirectAttributes.addFlashAttribute("errors", bindingResult.getFieldErrors());
            redirectAttributes.addFlashAttribute("device", deviceDAO.showOne(inventoryCard));
            redirectAttributes.addFlashAttribute("acts", actDAO.showActsByDevice(inventoryCard));
            return "redirect:/device/{inventoryCard}/edit";
        }

In addition, I cannot use the method with @ModelAttribute annotation because I need the value of device inventory card.

How I should handle this exception and keep acts on html form? Thanks in advance.