Question

我无法从Application Identity Users读取数据。我是初学者，任何想法？编译时没有错误。但我无法添加新任务。

我在创建任务时遇到错误https://localhost:44312/usertasks/Create

问题在于GET方法，但用户lis不为空

结果视图展开结果视图将枚举IEnumerable
[0] {lukas@wp.pl} UserTaskTest.Models.ApplicationUser AccessFailedCount 0 int ConcurrencyStamp“785f9a54-e7f1-4e3b-8bad-55165155d631”字符串电邮“lukas@wp.pl”字符串 EmailConfirmed false bool ExecutedUserTasks null System.Collections.Generic.ICollection Id“53f416ab-aa1e-465f-9dd4-dc32e11914ae”字符串 LockoutEnabled true bool LockoutEnd null System.DateTimeOffset？ NormalizedEmail“LUKAS@WP.PL”字符串 NormalizedUserName“LUKAS@WP.PL”字符串 OwnedUserTasks null System.Collections.Generic.ICollection PasswordHash“AQAAAAEAACcQAAAAEIqkXlzky + 4i8BsPl5Z4524B3Dj3u0RZMY2Rf5ch5l22GEMj5m0LsVgeWDAavmVO + g ==”string PhoneNumber null字符串 PhoneNumberConfirmed false bool SecurityStamp“698529ad-c47c-40f9-bdf3-c4d946cda86a”字符串 TwoFactorEnabled假布尔 UserName“lukas@wp.pl”string
[1] {li@wp.pl} UserTaskTest.Models.ApplicationUser AccessFailedCount 0 int ConcurrencyStamp“1a9064e2-3cc9-4794-9198-81423a5d8cd2”字符串电邮“li@wp.pl”字符串 EmailConfirmed false bool ExecutedUserTasks null System.Collections.Generic.ICollection Id“970839dc-31be-4966-8f06-e664aca3622c”字符串 LockoutEnabled true bool LockoutEnd null System.DateTimeOffset？ NormalizedEmail“LI@WP.PL”字符串 NormalizedUserName“LI@WP.PL”字符串 OwnedUserTasks null System.Collections.Generic.ICollection PasswordHash“AQAAAAEAACcQAAAAEM2KiwEfRDomBNiWXHmEtvwWEodfZDb8eaSADOGP2ZralzlnBDZEMQIsOvTk1nHMcw ==”string PhoneNumber null字符串 PhoneNumberConfirmed false bool SecurityStamp“0a829111-88d7-4a8a-b65d-5582cecbe67f”字符串 TwoFactorEnabled假布尔 UserName“li@wp.pl”string

System.NullReferenceException：未将对象引用设置为实例   一个物体   在
  Microsoft.AspNetCore.Mvc.Rendering.MultiSelectList.GetListItemsWithValueField（）
  在Microsoft.AspNetCore.Mvc.Rendering.MultiSelectList.GetListItems（）
  在Microsoft.AspNetCore.Mvc.Rendering.MultiSelectList.GetEnumerator（）

public class UserTask
{
    [Key]
    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
    public int UserTaskID { get; set; }

    public string Description { get; set; }

    [ForeignKey("OwnerUserID")]
    public string TaskOwnerId { get; set; }

    [ForeignKey("ExecutorUserID")]
    public string TaskExecutorId { get; set; }

    public virtual ApplicationUser OwnerUserID { get; set; }
    public virtual ApplicationUser ExecutorUserID { get; set; }

}


public class ApplicationUser : IdentityUser
{
     public ICollection<UserTask> OwnedUserTasks { get; set; }
     public ICollection<UserTask> ExecutedUserTasks { get; set; }
}

public class ApplicationDbContext : IdentityDbContext<ApplicationUser>
{

    public ApplicationDbContext(DbContextOptions<ApplicationDbContext> options) : base(options)
    {
    }

    public DbSet<UserTask> UserTask { get; set; }


    protected override void OnModelCreating(ModelBuilder builder)
    {
       base.OnModelCreating(builder);

       builder.Entity<ApplicationUser>()
           .HasMany(x => x.OwnedUserTasks)
           .WithOne(x => x.OwnerUserID);

       builder.Entity<ApplicationUser>()
           .HasMany(x => x.ExecutedUserTasks)
           .WithOne(x => x.ExecutorUserID);
    }
}

Startup.cs

public class Startup
{
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddDbContext<ApplicationDbContext>(options =>
            options.UseSqlServer(Configuration.GetConnectionString("DefaultConnection")));

        services.AddIdentity<ApplicationUser, IdentityRole>()
            .AddEntityFrameworkStores<ApplicationDbContext>()
            .AddDefaultTokenProviders();

        // Add application services.
        services.AddTransient<IEmailSender, EmailSender>();

        services.AddMvc();
    }
}

UserTaskControler

public class UserTasksController : Controller
{
    private readonly ApplicationDbContext _context;
    private readonly UserManager<ApplicationUser> _userManager;

    public UserTasksController(ApplicationDbContext context, UserManager<ApplicationUser> userManager)
    {
        _context = context;
        _userManager = userManager;
    }

    public IActionResult Create()
    {
        ViewData["TaskOwnerId"] = new SelectList(_userManager.Users.ToList(), "Id", "Name");

        ViewData["TaskExecutorId"] = new SelectList(_userManager.Users.ToList(), "Id", "Name");

        return View();
    }
}

和视图

@model UserTaskTest.Models.UserTask

@{
    ViewData["Title"] = "Create";
}

<h2>Create</h2>

<h4>UserTask</h4>
<hr />
<div class="row">
    <div class="col-md-4">
        <form asp-action="Create">
            <div asp-validation-summary="ModelOnly" class="text-danger"></div>
            <div class="form-group">
                <label asp-for="Description" class="control-label"></label>
                <input asp-for="Description" class="form-control" />
                <span asp-validation-for="Description" class="text-danger"></span>
            </div>
            <div class="form-group">
                <label asp-for="TaskOwnerId" class="control-label"></label>
                 <select asp-for="TaskOwnerId" class="form-control" asp-items="ViewBag.TaskOwnerId"></select>
            </div>
            <div class="form-group">
             <!--   <label asp-for="TaskExecutorId" class="control-label"></label>
                <select asp-for="TaskExecutorId" class="form-control" asp-items="ViewBag.TaskExecutorId"></select> -->
            </div>
            <div class="form-group">
                <input type="submit" value="Create" class="btn btn-default" />
            </div>
        </form>
    </div>
</div>

<div>
    <a asp-action="Index">Back to List</a>
</div>

@section Scripts {
    @{await Html.RenderPartialAsync("_ValidationScriptsPartial");}
}

Answer 1

_userManager导致此问题。这是因为更改跟踪以及您尝试更改ForeignKeys的{{1}}的性质。尝试使用User填充您的下拉列表，虽然它在生成的上下文中不显示，但它是继承礼物。

除非您在ApplicationUser中实际创建了该属性，否则您的下拉列表中的_dbContext.Users.ToList()将会出错，因为默认情况下它不存在。 https://github.com/aspnet/Identity/blob/dev/src/Microsoft.Extensions.Identity.Stores/IdentityUser.cs

Name

如何将Identity dbcontext与应用程序上下文合并？

1 个答案: