Spring Boot thymeleaf 错误请求 400 而不是显示用户错误

Question

我正在尝试使用发布请求提交表单并首先验证输入。

但是，当我输入错误（例如全部为空）而不是显示错误时，我收到错误请求 (400)。

为了显示错误，我在 HTML 中使用了 th:if 和 th:errors 标签。

如果我提交所有有效输入，则没有问题。

控制器类：

@Controller
@RequestMapping(path = "/order")
public class PurchaseController
{
    @GetMapping(path = "/new")
    public String newOrder(Model model)
    {
        model.addAttribute("Purchase", new Purchase());
        return "neworder";
    }

    @PostMapping(path = "/new")
    public String createPurchase(@Valid @ModelAttribute(name = "Purchase") Purchase purchase)
    {
        int purchaseId = 0;
        try
        {
            purchaseId = PurchaseManager.insertPurchase(purchase);
        }
        catch (SQLException e)
        {
            return "purchaseerror";
        }
        if (purchaseId == 0)
            return "purchaseerror";
        return "redirect:/order/success?id=" + purchaseId;
    }

    @GetMapping(path = "/success")
    public String successPurchase(@RequestParam(required = true, name = "id") int id, Model model)
    {
        model.addAttribute("id", id);
        return "ordersuccess";
    }
}

HTML 表单：

<form th:action="@{new}" th:object="${Purchase}" method="post">
                <table>
                    <tr>
                        <td>First name:</td>
                        <td><input type="text" th:field="*{firstName}" /></td>
                        <td th:if="${#fields.hasErrors('firstName')}"
                            th:errors="*{firstName}">Must be filled</td>
                        <td>Last name:</td>
                        <td><input type="text" th:field="*{lastName}" /></td>
                        <td th:if="${#fields.hasErrors('lastName')}"
                            th:errors="*{lastName}">Must be filled</td>
                    </tr>
                    <tr>
                        <td>Adresa:</td>
                        <td><input type="text" th:field="*{address}" /></td>
                        <td th:if="${#fields.hasErrors('address')}" th:errors="*{address}">Must be filled</td>
                    </tr>
                    <tr>
                        <td>ico:</td>
                        <td><input type="text" th:field="*{ico}" /></td>
                        <td th:if="${#fields.hasErrors('ico')}" th:errors="*{ico}">Must be filled</td>
                        <td>dic:</td>
                        <td><input type="text" th:field="*{dic}" /></td>
                        <td th:if="${#fields.hasErrors('dic')}" th:errors="*{dic}">Must be filled</td>
                    </tr>
                    <tr>
                        <td>Email:</td>
                        <td><input type="text" th:field="*{email}" /></td>
                        <td th:if="${#fields.hasErrors('email')}" th:errors="*{email}">Must be filled</td>
                        <td>phone:</td>
                        <td><input type="text" th:field="*{phone}" /></td>
                        <td th:if="${#fields.hasErrors('phone')}" th:errors="*{phone}">Must be filled</td>
                    </tr>
                </table>
                <input type="submit" value="Submit"/>
            </form>

模型类（购买）

public class Purchase
{
    private int id;

    @NotBlank
    @Size(max = 50)
    private String firstName;

    @NotBlank
    @Size(max = 50)
    private String lastName;

    @NotBlank
    @Size(max = 50)
    private String ico;

    @NotBlank
    @Size(max = 50)
    private String dic;

    @NotBlank
    @Size(max = 400)
    private String address;

    @NotBlank
    @Size(max = 50)
    private String email;

    @NotBlank
    @Size(max = 50)
    private String phone;

    private LocalDateTime creationDate;

    ... getters and setters, constructors

如何使用 thymeleaf 显示错误？

编辑： 我设法通过将 BindingResult 参数添加到 Controller 类中的 post 方法并检查是否有任何错误来使其工作。如果是，我返回表单所在的同一页面（/new 映射），即“neworder”。

return "purchaseerror"; 可能会造成一些混乱。

@PostMapping(path = "/new")
    public String createPurchase(@Valid @ModelAttribute(name = "Purchase") Purchase purchase, BindingResult result)
    {
        if (result.hasErrors())
        {
            return "neworder";
        }
        int purchaseId = 0;
        try
        {
            purchaseId = PurchaseManager.insertPurchase(purchase);
        }
        catch (SQLException e)
        {
            return "redirect:/purchaseerror";
        }
        if (purchaseId == 0)
            return "redirect:/purchaseerror";
        return "redirect:/order/success?id=" + purchaseId;
    }

Answer 1

如果您在createPurchase 方法中使用Model 作为第二个参数，我认为您的问题可能会得到解决。然后在您的方法中，您可以执行以下操作来添加消息：

@PostMapping("/add")
    public String addUser(@Valid User user, BindingResult result, Model model) {
        if (result.hasErrors()) {
            return "errors/addUser";
        }
        repository.save(user);
        model.addAttribute("users", repository.findAll()); //this is what you could do.
        return "errors/home";
    }

这会导致您的方法如下（请自行决定修改它——我只是为了演示目的而写）：

@PostMapping(path = "/new")
    public String createPurchase(@Valid @ModelAttribute(name = "Purchase") Purchase purchase, Model model)
    {
        int purchaseId = 0;
        try
        {
            purchaseId = PurchaseManager.insertPurchase(purchase);
        }
        catch (SQLException e)
        {
            // todo: don't return right away. Add `model.addAttribute` first.
            return "purchaseerror";
        }
        if (purchaseId == 0) {
            // todo: don't return right away. Add `model.addAttribute` first.
            return "purchaseerror";
        }
        
        return "redirect:/order/success?id=" + purchaseId;
    }

然后，您的 Thymeleaf 实现将选择 modelAttribute 中添加的值，您可以从中选择错误（因为您将填充它）并简单地基于此逻辑。

您可以按照示例from here 更好地理解。请记住，您需要先添加到Model，然后才能根据它在百里香中布置逻辑。

希望我的回答能解决您的疑问。如果没有，请道歉。