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[英]Why is my redirectAttributes.addFlashAttribute and data Re-populating not working after validation fails?
[英]addFlashAttribute and holding data
使用addFlashAttribute時應如何保存POST請求中的數據?
@GetMapping("/collage")
public String paintPicture(@ModelAttribute(value="picture") String img){
//How to hold 'img' here?
//When I send GET I want to see the image again (not only after the redirect).
return "collage";
}
@PostMapping(value="/sending")
public String redirect(@RequestParam(value="image") MultipartFile img, RedirectAttributes redirectAttr) throws IOException {
String imgAsBase64 = Base64.encodeBase64String(img.getBytes());
redirectAttr.addFlashAttribute("picture",imgAsBase64);
return "redirect:/collage";
}
RequestMappingHandlerAdapter
將FlashMap
(包含Flash變量)存儲為請求屬性。 重定向后,將出現一個全新的請求,因此閃存變量將丟失。 似乎Flash var無法在這里使用。
您可以改用會話:
session.setAttribute("picture", imgAsBase64);
接着
String imgAsBase64 = (String) session.getAttribute("picture");
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