使用Thymeleaf提交更新客户表单时出现Required body is missing错误求助

Thymeleaf传统表单提交的是application/x-www-form-urlencoded或multipart/form-data格式的表单数据，但@RequestBody注解要求请求体是JSON/XML这类序列化格式，Spring无法将表单数据解析为CustomerDTO对象，因此抛出"Required body is missing"错误。

方案一：改用@ModelAttribute接收表单数据（推荐，适配传统表单场景） #

修改控制器方法，将@RequestBody替换为@ModelAttribute，Spring会自动将表单参数绑定到CustomerDTO实例：

@RequestMapping(path = "updateCustomerForm/{identityNumber}")
public String updateCustomerForm(@PathVariable("identityNumber") String identityNumber, 
                                 @ModelAttribute CustomerDTO customer){
    customerService.updateCustomer(identityNumber,customer);
    return "redirect:/customer/showList";
}

同时调整Thymeleaf表单：

• 浏览器原生不支持PUT请求，将表单method改为POST，靠_method隐藏字段模拟PUT请求（Spring Boot默认已开启HiddenHttpMethodFilter支持该功能）
• 修正action路径的变量写法，确保identityNumber正确传入
• 移除重复的identityNumber隐藏字段（th:field已自动生成对应input）

<form th:action="@{/customer/updateCustomerForm/{id}(id=${customer.identityNumber})}" 
      th:object="${customer}" 
      method="post">
    <input name="_method" type="hidden" value="put" />
    <input type="text" th:field="*{identityNumber}" placeholder="Enter identity number" class="form-control col-4 mb-4" />
    <input type="text" th:field="*{name}" placeholder="Enter name" class="form-control col-4 mb-4" />
    <input type="text" th:field="*{surname}" placeholder="Enter surname" class="form-control col-4 mb-4" />
    <input type="text" th:field="*{phoneNumber}" placeholder="Enter phone number" class="form-control col-4 mb-4" />
    <input type="text" th:field="*{salary}" placeholder="Enter salary" class="form-control col-4 mb-4" />
    <input type="text" th:field="*{age}" placeholder="Enter age" class="form-control col-4 mb-4" />
    <button class="btn btn-primary col-2" type="submit">Save</button>
</form>

方案二：用AJAX提交JSON数据（适配@RequestBody场景） #

如果必须保留@RequestBody，需要通过AJAX将表单数据转为JSON格式提交：
首先明确控制器的请求类型和Content-Type：

@RequestMapping(path = "updateCustomerForm/{identityNumber}", method = RequestMethod.PUT, consumes = MediaType.APPLICATION_JSON_VALUE)
public String updateCustomerForm(@PathVariable("identityNumber") String identityNumber, 
                                 @RequestBody CustomerDTO customer){
    customerService.updateCustomer(identityNumber,customer);
    return "redirect:/customer/showList";
}

然后修改表单，用JavaScript处理提交逻辑：

<form th:object="${customer}" id="updateForm">
    <input type="text" th:field="*{identityNumber}" placeholder="Enter identity number" class="form-control col-4 mb-4" />
    <input type="text" th:field="*{name}" placeholder="Enter name" class="form-control col-4 mb-4" />
    <input type="text" th:field="*{surname}" placeholder="Enter surname" class="form-control col-4 mb-4" />
    <input type="text" th:field="*{phoneNumber}" placeholder="Enter phone number" class="form-control col-4 mb-4" />
    <input type="text" th:field="*{salary}" placeholder="Enter salary" class="form-control col-4 mb-4" />
    <input type="text" th:field="*{age}" placeholder="Enter age" class="form-control col-4 mb-4" />
    <button class="btn btn-primary col-2" type="button" onclick="submitForm()">Save</button>
</form>

<script>
function submitForm() {
    const form = document.getElementById('updateForm');
    const formData = new FormData(form);
    const customer = {};
    formData.forEach((value, key) => {
        customer[key] = value;
    });
    const identityNumber = customer.identityNumber;
    
    fetch(`/customer/updateCustomerForm/${identityNumber}`, {
        method: 'PUT',
        headers: {
            'Content-Type': 'application/json',
            'Accept': 'text/html'
        },
        body: JSON.stringify(customer)
    }).then(response => {
        if (response.ok) {
            window.location.href = '/customer/showList';
        }
    }).catch(error => {
        console.error('Error:', error);
    });
}
</script>

内容的提问来源于stack exchange，提问作者Ege Coskun