在REST中测试POST请求

我使用Postman（chrome扩展）来测试这个REST服务，我能够成功测试GET和DELETE： http://localhost:8080/mt-rest/rest/user/321 ，但不能POST，即使在提供表单数据之后 . 我得到..服务器拒绝了这个请求，因为请求实体的格式不受所请求方法所请求资源的支持 . 我在这做错了什么？

@Controller
@RequestMapping("rest")
public class TestController {![enter image description here][2]

    @Autowired
    private MultitenantService service;

    @RequestMapping(value = "/user/{id}", method = RequestMethod.GET)
    @ResponseBody
    public User getUserInfo(@PathVariable Long id) {
        return service.getUser(id);
    }

    @RequestMapping(value = "/user", method = RequestMethod.GET)
    @ResponseBody
    public List<User> getCustomers() {
        return service.getUsers();
    }

    @RequestMapping(value = "/user/{id}/todo", method = RequestMethod.GET)
    @ResponseBody
    public List<TodoItem> getTransactions(@PathVariable Long id) {
        return getUserInfo(id).getTodoItems();
    }

    @RequestMapping(value = "/user/{id}/todo", method = RequestMethod.POST)
    @ResponseBody
    public List<TodoItem> addTransaction(@PathVariable Long id, @RequestBody TodoItem todoItem) {

        User user = getUserInfo(id);
        user.getTodoItems().add(todoItem);

        service.save(user);

        return user.getTodoItems();
    }

    @RequestMapping(value = "/user/{id}/todo/{todoId}", method = RequestMethod.DELETE)
    @ResponseBody
    public User addTransaction(@PathVariable Long id, @PathVariable Long todoId) {

        User user = getUserInfo(id);

        user.deleteTodo(todoId);

        service.save(user);

        return getUserInfo(id);
    }
}

Update:

在我的POST方法中，我从@RequestBody更改为@ModelAttribute，现在我得到了

org.springframework.web.util.NestedServletException: Request processing failed; nested exception is javax.validation.ConstraintViolationException: Validation failed for classes [net.tajzich.mt.domain.TodoItem] during persist time for groups [javax.validation.groups.Default, ]
List of constraint violations:[
    ConstraintViolationImpl{interpolatedMessage='may not be null', propertyPath=name, rootBeanClass=class net.tajzich.mt.domain.TodoItem, messageTemplate='{javax.validation.constraints.NotNull.message}'}

]