在选择框中返回 Null 以选择城市和州

Question

这是我的 2 个模型。我添加迁移并成功更新。

  public class UserInfo : BaseEntity
{
    #region FirstSartProgram

    public long UserPackageId { get; set; }

    [Display(Name = "Address")]
    [MaxLength(350)]
    public string Address { get; set; }

    [Display(Name = "Job")]
    [MaxLength(150)]
    public string Job { get; set; }

    [Display(Name = "UserInfoSituation")]
    public UserInfoSituation? UserInfoSituation { get; set; }

    .....


     public long? LocationId { get; set; }

#region Relations

    public ICollection<PackageFile> PackageFiles { get; set; }

    [ForeignKey("UserPackageId")]
    public UserPackage UserPackage { get; set; }

    [ForeignKey("LocationId")]
    public Location.Location Location { get; set; }

    #endregion

第二个是：

   #region Properties

    [Display(Name = "Title")]
    [Required(ErrorMessage = "Required")]
    [MaxLength(200)]
    public string Title { get; set; }

    public long? ParentId { get; set; }

    [Display(Name = "IsDeleted")]
    public bool IsDeleted { get; set; }

    [Display(Name = "IsActive")]
    public bool IsActive { get; set; }

    #endregion

    #region Relations

    [ForeignKey("ParentId")]
    public Location Parent { get; set; }

 
    public ICollection<UserInfo.UserInfo>  UserInfos { get; set; }

    #endregion

---

正如我所说的更新数据库是好的。 我写了一些创建表单的方法。但是当我想用这个方法创建或编辑时，我有错误：

    [HttpPost("userInfo/first-start-userInfo/{packageId}")]
    public async Task<IActionResult> FirstStartUserInfo(CreateFirstStartUserInfoViewModel firstStartUserInfo)
    {
        var userId = User.GetCurrentUserId();
        if (!ModelState.IsValid) return View(firstStartUserInfo);
        var res = await _packageService.CreateFirstStartUserInfoByUser(firstStartUserInfo, userId);
        switch (res.UserInfoType)
        {
            case UserInfoType.NotValid: return RedirectToAction("NotFound","Home");
            case UserInfoType.NotFound: return RedirectToAction("NotFound","Home");
            case UserInfoType.Success:
                return RedirectToAction("SecondStartUserInfo", "UserInfo", new { UserInfoId = res.UserInfoId,menu=UserPanelMenu.Packages });
        }
        return View(firstStartUserInfo);
    }

我在选择列表中看到了城市和州。 但是当我创建表单时，数据库中的位置 ID 为空

查看：

 <form method="post" asp-controller="UserInfo" asp-action="FirstStartUserInfo" asp-route-menu="Packages">
            <input type="hidden" asp-for="PackageId" />
            <div>
                <div class="col-xl-7">
                    
                    
                    <div class="my-4">
                        <label class="w-100 d-flex align-items-center" for="">
                            <label>State </label>
                          
                            <select   asp-for="LocationId" asp-items="(IEnumerable<SelectListItem>)@ViewData["State"]"  class="form-control">
                               
                            </select>
                            <label>city </label>
                            <select  asp-for="LocationId" asp-items="(IEnumerable<SelectListItem>)@ViewData["City"]" id=" " class="form-control ">
                              
                            </select>
                        </label>
                     
                    </div>

........

 @{
ViewData["Title"] = _localizer["GetUserInfo"];
IEnumerable<UserLocationViewModel> state = ViewData["State"] as IEnumerable<UserLocationViewModel>;   
IEnumerable<UserLocationViewModel> city = ViewData["City"] as IEnumerable<UserLocationViewModel>;   

}

Answer 1

LocationId 为空，因为您没有从选择列表 ID @ViewData["State","YouStateId"] 传递它。

试试这个：-

<select   asp-for="LocationId" asp-items="(IEnumerable<SelectListItem>)@ViewData["State","YouStateId"]"  class="form-control">

在这里你使用选择列表传递StateId。当您创建时，您会发现 LocationId 与您所在的州/城市。

您实际上并没有清楚地发布您的模型。我假设您的模型设计没问题，并且您的所有模型都有一个主键。还可以根据需要在模型中为城市和州提供单独的 ForeignKey。