java - 将错误消息从 Controller 传递到 thymeleaf

Question

我不知道如何在表单之外将错误传递给 thymeleaf，而不是特定于某个字段。如果这本书有货，只需检查一下即可。如果是，则处理所有内容。如果不是，则在客户端抛出错误消息。

Controller

@PostMapping("/books/borrow/{id}")
    public String borrowBook(@PathVariable int id, Errors errors) {

        Book borrowedBook = bookRepository.findById(id);

        if (borrowedBook.getAvailableCount() == 0){
            errors.rejectValue("onStock", "Book out of stock. Come later...");
            return "redirect:/books/";
        } else{...}

查看

<p th:text="${onStock}"></p>

我不明白如何传递参数并将其显示给客户端。我做了研究https://www.thymeleaf.org/doc/tutorials/2.1/thymeleafspring.html#validation-and-error-messages但它们都是特定于表单和字段的。

我做错了什么？

Answer 1

您可以使用 RedirectAttribute 来实现:

Controller

@PostMapping("/books/borrow/{id}")
    public String borrowBook(@PathVariable int id, Errors errors, RedirectAttributes redirectAttributes) {
    Book borrowedBook = bookRepository.findById(id);

    if (borrowedBook.getAvailableCount() == 0){
        errors.rejectValue("onStock", "Book out of stock. Come later...");
        redirectAttributes.addFlashAttribute("errorMessage", "We couldn't process your order!");
        return "redirect:/books/borrow/" + id;
    } else {
        //Process the request
    }

模板(HTML)

<div th:if="${errorMessage}">
    <div th:text="${errorMessage}"></div>
</div>