Razor页面与AJAX提交数据时出现Status 400错误排查

开发医疗类网站，流程为：收集患者邮箱判断状态——未登录跳转登录页；未注册则自动生成随机密码发邮件完成注册。已登录用户及未登录常规流程正常，但新用户注册后提交后续问题数据时，出现Status 400错误。

后端代码（C#） #

public async Task<IActionResult> OnGetCheckUserAsync(string Email)
{
        if (User.Identity.IsAuthenticated)
        {
            var UserCred = _userManagmentServices.GetProfileAsync(Email).Result;
            ProfileModel = new ProfileModel()
            {
                Id = UserCred.Id,
                Email = UserCred.Email,
                Name = UserCred.Name,
                Applications = UserCred.Applications,
                Address = UserCred.Address,
                City = UserCred.City,
                DisplayName = UserCred.DisplayName,
                Phone = UserCred.Phone,
                PostalCode = UserCred.PostalCode,
            };

            return new JsonResult(ProfileModel);
        }
        else
        {
            var user = await _userManager.FindByEmailAsync(Email);

            if (user == null)
            {
                string randomString = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890!@#$%^&*";
                Random random = new Random();
                char[] myPassword = new char[6];

                for (int i = 0; i < 6; i++)
                {
                    myPassword[i] = randomString[(int)(35 * random.NextDouble())];
                }
                var randomPassword = string.Concat(myPassword);

                var UserModel = new UserModel()
                {
                    Email = Email,
                    FirstName = "Mr",
                    LastName = "Patient",
                    Password = randomPassword,
                    PhoneNo = "03000000000",
                };

                var response = await _userManagmentServices.CreateAsync(UserModel);

                if (response.IsSuccessful)
                {
                    var Body = $"Dear {UserModel.FirstName + UserModel.LastName}  Your password is auto generated successfull and your password is {UserModel.Password}";
                    await _mailServices.SendEmailNotificationAsync(UserModel.Email, "Auto Generated Password", Body);
                }

                if (!response.IsSuccessful)
                {
                    foreach (var Error in response.Errors)
                    {
                        ModelState.AddModelError("", Error.ToString());
                    }

                    return new JsonResult("Error while creating your account");
                }

                var UserCred = _userManagmentServices.GetProfileAsync(UserModel.Email).Result;

                ProfileModel = new ProfileModel()
                {
                    Id = UserCred.Id,
                    Email = UserCred.Email,
                    Name = UserCred.Name,
                    Applications = UserCred.Applications,
                    Address = UserCred.Address,
                    City = UserCred.City,
                    DisplayName = UserCred.DisplayName,
                    Phone = UserCred.Phone,
                    PostalCode = UserCred.PostalCode,
                };

                return new JsonResult(ProfileModel);
            }
            else
            {
                application = new FEApplication();
                application.Status = Status.Incomplete;
                application.UserEmail = Email;
                application.ApplicationType = "Premature Ejaculation";
                application.FlowId = await _applicationManagementService.Create(application);
                var _signinUrl = "../Auth/Signin";
                return new JsonResult(_signinUrl);
            }
        }
}

public async Task<IActionResult> OnPostSubmitAsync(FEApplication? application)
{
        if (application.FlowId != null)
        {
            application.ApplicationType = "Premature Ejaculation";

            if (application.DoctorToKnow == "No" || application.ExplainDoctorToKnow != null)
            {
                application.Status = Status.PaymentDue;
            }
            else
            {
                application.Status = Status.Incomplete;
            }

            await _applicationManagementService.UpdatePEAsync(application.FlowId, application);
        }
        else
        {
            if (User.Identity.IsAuthenticated)
            {
                application.PatientUserName = ProfileModel.DisplayName;
                application.ApplicationType = "Premature Ejaculation";
                application.Status = Status.Incomplete;
                application.UserEmail = User?.Identity?.Name;
                ProfileModel = _userManagmentServices.GetProfileAsync(application.UserEmail).Result;
            }
            else
            {
                application.PatientUserName = ProfileModel.DisplayName ?? string.Empty;
                application.UserEmail = application.UserEmail;
            }
            application.Status = Status.Incomplete;
            application.ApplicationType = "Premature Ejaculation";
            application.FlowId = await _applicationManagementService.Create(application);
            //_application = _applicationManagementService.GetOneById(FlowId);
        }

        return new JsonResult(application.FlowId);
}

前端代码（JavaScript） #

function CheckUserEmail() {
$("#modalspinner").show();
var email = document.getElementById("Email").value;
$.ajax({
    beforeSend: function (xhr) {
        xhr.setRequestHeader("XSRF-TOKEN",
            $('input:hidden[name="__RequestVerificationToken" ]').val());
    },
    url: "./Start?handler=CheckUser",
    type: "GET",
    dataType: "json",
    data: {
        Email: email
    },
    success: function (response) {
        console.log("Success block");
        if (response) {
            $("#modalspinner").hide();
            console.log("response " + response)
            if (response == "../Auth/Signin") {
                window.location.href = response;
            }
            else {
                if (response.id) {
                    console.log("if block =" + JSON.stringify(response));
                    var firstName = JSON.stringify(response.displayName) ?? "";
                    var lastName = JSON.stringify(response.displayName) ?? "";
                    var email = JSON.stringify(response.email) ?? "";
                    var phoneNo = JSON.stringify(response.phone);
                    var address = JSON.stringify(response.address) ?? "";
                    var city = JSON.stringify(response.city);
                    var postalCode = JSON.stringify(response.postalCode) ?? "";
                    $("#FirstName").val(firstName.replace(/\"/g, ""));
                    $("#LastName").val(lastName.replace(/\"/g, ""));
                    $("#Email").val(email.replace(/\"/g, ""));
                    $("#PhoneNoTextbox").val(phoneNo.replace(/\"/g, ""));
                    $("#CustomerShippingAddress").val(address.replace(/\"/g, ""));
                    $("#CustomerCity").val(city.replace(/\"/g, ""));
                    $("#CustomerPostalCode").val(postalCode.replace(/\"/g, ""));
                    console.log("response data :" + firstName, lastName, email, phoneNo, address, city, postalCode);
                }
                else {
                    $("#modalspinner").hide();
                    console.log("Error while creating new user" + JSON.stringify(response));
                }
            }

        }
    },
    error: function (response) {
        console.log("Error block =" + JSON.stringify(response));
        $("#modalspinner").hide();
        $('#EmailMessage').show();
        setTimeout(function () { $('#EmailMessage').hide(); }, 5000);
        $("#modalspinner").hide();
    }
});
}
   
function SubmitForm() {
    /*var flowId = document.getElementById("FlowId").value;*/
    var data = $("#ApplicationData").serialize();
    console.log("data :" + data);
    $.ajax({
        beforeSend: function (xhr) {
            xhr.setRequestHeader("XSRF-TOKEN",
                $('input:hidden[name="__RequestVerificationToken" ]').val());
        },
        type: "POST",
        url: "./Start?handler=Submit",
        contentType: "application/x-www-form-urlencoded; charset=UTF-8",
        data: data,
        success: function (response) {

            var res = JSON.stringify(response);
            console.log("Application data saved!");
            $("#FlowId").val(res.replace(/\"/g, ""));
        }
    })
} 

问题排查与解决方案 #

核心原因推测 #

1. 未登录用户的ProfileModel状态丢失：新用户注册后，CheckUserEmail返回ProfileModel数据，但用户仍未登录。后续SubmitForm调用后端接口时，页面级的ProfileModel可能未持久化，导致OnPostSubmitAsync中依赖该模型的字段为空，触发模型验证失败。
2. 异步方法同步调用异常：代码中多次用.Result调用异步方法（如_userManagmentServices.GetProfileAsync(Email).Result），易引发线程阻塞或上下文异常，导致数据未正确加载。
3. FEApplication模型验证不通过：后端接收参数时，若UserEmail等必填字段为空、格式不符合要求，ASP.NET Core自动模型验证会直接返回400错误。

具体修复步骤 #

• 修复异步调用方式：将所有.Result替换为await，避免线程死锁：

  // 原代码
  var UserCred = _userManagmentServices.GetProfileAsync(Email).Result;
  // 修改为
  var UserCred = await _userManagmentServices.GetProfileAsync(Email);
  

• 避免依赖未持久化的ProfileModel：在OnPostSubmitAsync的未登录分支中，直接使用前端提交的数据，而非依赖页面级变量：

  else
  {
      application.PatientUserName = application.PatientUserName ?? string.Empty;
      if(string.IsNullOrEmpty(application.UserEmail))
      {
          ModelState.AddModelError("", "用户邮箱不能为空");
          return BadRequest(ModelState);
      }
      application.Status = Status.Incomplete;
      application.ApplicationType = "Premature Ejaculation";
      application.FlowId = await _applicationManagementService.Create(application);
  }
  

• 添加模型验证日志：在OnPostSubmitAsync开头添加验证检查，明确错误原因：

  public async Task<IActionResult> OnPostSubmitAsync(FEApplication? application)
  {
      if(!ModelState.IsValid)
      {
          var errors = ModelState.Values.SelectMany(v => v.Errors).Select(e => e.ErrorMessage);
          return BadRequest(string.Join(";", errors));
      }
      // 原有逻辑...
  }
  

• 前端确保提交数据完整性：确认#ApplicationData表单包含UserEmail等必填字段，避免提交空值。

内容的提问来源于stack exchange，提问作者IR'Shah