尝试在 asp.net 中创建多对多关系时出错

Question

我在尝试创建多对多关系模型时遇到了 Asp.Net 问题，尝试注册帐户时出现此错误：

序列不包含匹配元素

当我“禁用”我的更改时，我可以正常在网站上注册，因此我的模型中存在一些关于列结构的错误，但我无法自己修复它们。我想在Bookmark 和Tag 表之间创建多对多连接，并且多对多表应具有以下结构：Id、BookmarkID、TagID。

这是我的模型：

public class Bookmark
{   
    [Key]
    public int BookmarkID { get; set; }

    public string Url { get; set; }

    public ApplicationUser UserId { get; set; }

    public virtual ICollection<BookmarkTag> BookmarkTags { get; set; }
}

public class Tag
{
    [Key]
    public int TagID { get; set; }

    [Column(TypeName="varchar(60)")]
    public string TagName { get; set; }

    public virtual ICollection<BookmarkTag> BookmarkTags { get; set; }
}

public class BookmarkTag
{
    [Key, Column(Order = 0)]
    public int BookmarkTagID { get; set; }

    [Key, Column(Order = 1)]
    public int BookmarkID { get; set; }

    [Key, Column(Order = 2)]
    public int TagID { get; set; }

    public virtual Bookmark Bookmark { get; set; }
    public virtual Tag Tag { get;  set;}
}

这里也是错误堆栈跟踪：

[InvalidOperationException：序列不包含匹配元素]
System.Linq.Enumerable.Single（IEnumerable1 source, Func2 谓词） +2603017 System.Data.Entity.Utilities.DbProviderManifestExtensions.GetStoreTypeFromName(DbProviderManifest providerManifest，字符串名称）+81
System.Data.Entity.ModelConfiguration.Configuration.Properties.Primitive.PrimitivePropertyConfiguration.ConfigureColumn（EdmProperty 列、EntityType 表、DbProviderManifest providerManifest) +87
System.Data.Entity.ModelConfiguration.Configuration.Properties.Primitive.PrimitivePropertyConfiguration.Configure(EdmProperty 列、EntityType 表、DbProviderManifest providerManifest、Boolean allowOverride，布尔型 fillFromExistingConfiguration) +138
System.Data.Entity.ModelConfiguration.Configuration.Properties.Primitive.c__DisplayClass4.b__3(Tuple2 pm) +38
System.Data.Entity.Utilities.IEnumerableExtensions.Each(IEnumerable1 ts, 行动1 action) +130
System.Data.Entity.ModelConfiguration.Configuration.Properties.Primitive.PrimitivePropertyConfiguration.Configure(IEnumerable1 propertyMappings, DbProviderManifest providerManifest, Boolean allowOverride，布尔型 fillFromExistingConfiguration) +94
System.Data.Entity.ModelConfiguration.Configuration.Types.StructuralTypeConfiguration.ConfigurePropertyMappings（IList1 propertyMappings, DbProviderManifest providerManifest, Boolean allowOverride) +154
System.Data.Entity.ModelConfiguration.Configuration.Types.EntityTypeConfiguration.ConfigurePropertyMappings(DbDatabaseMapping databaseMapping, EntityType entityType, DbProviderManifest providerManifest, Boolean allowOverride) +585
System.Data.Entity.ModelConfiguration.Configuration.Types.EntityTypeConfiguration.Configure(EntityType entityType, DbDatabaseMapping databaseMapping, DbProviderManifest providerManifest) +177
System.Data.Entity.ModelConfiguration.Configuration.ModelConfiguration.ConfigureEntityTypes(DbDatabaseMapping databaseMapping, ICollection1 entitySets，DbProviderManifest 供应商清单）+423
System.Data.Entity.ModelConfiguration.Configuration.ModelConfiguration.Configure（DbDatabaseMapping 数据库映射，DbProviderManifest providerManifest) +376
System.Data.Entity.DbModelBuilder.Build（DbProviderManifest providerManifest, DbProviderInfo providerInfo) +444
System.Data.Entity.DbModelBuilder.Build（DbConnection 提供者连接）+55
System.Data.Entity.Internal.LazyInternalContext.CreateModel（LazyInternalContext 内部上下文）+61
System.Data.Entity.Internal.RetryLazy2.GetValue(TInput input) +123
System.Data.Entity.Internal.LazyInternalContext.InitializeContext() +616 System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType) +18
System.Data.Entity.Internal.Linq.InternalSet1.Initialize() +53
System.Data.Entity.Internal.Linq.InternalSet1.get_InternalContext() +16 System.Data.Entity.Infrastructure.DbQuery1.System.Linq.IQueryable.get_Provider() +39 System.Data.Entity.QueryableExtensions.FirstOrDefaultAsync（IQueryable1 source, Expression1 谓词，CancellationToken cancelToken） +154 System.Data.Entity.QueryableExtensions.FirstOrDefaultAsync（IQueryable1 source, Expression1 谓词）+163
Microsoft.AspNet.Identity.EntityFramework.d__6c.MoveNext() +472 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务 任务）+99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务 任务）+58 Microsoft.AspNet.Identity.CultureAwaiter1.GetResult() +59 Microsoft.AspNet.Identity.<ValidateUserName>d__4.MoveNext() +594 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58 Microsoft.AspNet.Identity.<ValidateAsync>d__0.MoveNext() +266 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58 Microsoft.AspNet.Identity.<CreateAsync>d__0.MoveNext() +568 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58 Microsoft.AspNet.Identity.<CreateAsync>d__d.MoveNext() +483 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) +99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task) +58 System.Runtime.CompilerServices.TaskAwaiter1.GetResult() +28 BookIT.Controllers.d__15.MoveNext() 在 D:\Projekti\CS\BookIT\BookIT\Controllers\AccountController.cs:155
System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess（任务 任务）+99
System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification（任务 任务）+58
System.Web.Mvc.Async.TaskAsyncActionDescriptor.EndExecute（IAsyncResult asyncResult) +97
System.Web.Mvc.Async.c__DisplayClass37.b__36(IAsyncResult 异步结果）+17
System.Web.Mvc.Async.WrappedAsyncResult1.CallEndDelegate(IAsyncResult asyncResult) +10
System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod（IAsyncResult asyncResult) +32
System.Web.Mvc.Async.AsyncInvocationWithFilters.b__3d() +50 System.Web.Mvc.Async.c__DisplayClass46.b__3f() +225 System.Web.Mvc.Async.c__DisplayClass33.b__32(IAsyncResult asyncResult) +10
System.Web.Mvc.Async.WrappedAsyncResult1.CallEndDelegate(IAsyncResult asyncResult) +10
System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters（IAsyncResult asyncResult) +34
System.Web.Mvc.Async.c__DisplayClass2b.b__1c() +26 System.Web.Mvc.Async.c__DisplayClass21.b__1e(IAsyncResult asyncResult) +100
System.Web.Mvc.Async.WrappedAsyncResult1.CallEndDelegate(IAsyncResult asyncResult) +10
System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction（IAsyncResult asyncResult) +27
System.Web.Mvc.Controller.b__1d（IAsyncResult asyncResult，ExecuteCoreState 内部状态）+13
System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult asyncResult) +29
System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49
System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +36 System.Web.Mvc.Controller.b__15（IAsyncResult asyncResult，控制器控制器）+12
System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult asyncResult) +22
System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49
System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +26
System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute（IAsyncResult asyncResult) +10
System.Web.Mvc.MvcHandler.b__5（IAsyncResult asyncResult, ProcessRequestState innerState) +21
System.Web.Mvc.Async.WrappedAsyncVoid1.CallEndDelegate(IAsyncResult asyncResult) +29
System.Web.Mvc.Async.WrappedAsyncResultBase1.End() +49
System.Web.Mvc.MvcHandler.EndProcessRequest（IAsyncResult asyncResult） +28 System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult 结果）+9
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9711525 System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

提前致谢

添加：

  if (ModelState.IsValid)
        {
            var user = new ApplicationUser { UserName = model.Email, Email = model.Email };
            var result = await UserManager.CreateAsync(user, model.Password);
            if (result.Succeeded)
            {

Answer 1

最后我找到了导致错误的原因... 就是这条线

 [Column(TypeName="varchar(60)")]
public string TagName { get; set; }

当我删除 Column(TypeName) 部分时，代码可以毫无问题地进行编译...它现在可以工作，但我不确定它为什么会这样或为什么会抛出该错误。谁能解释为什么它以前不起作用？

Answer 2

您的 Key 属性太多，EF 框架无法计算出您的模型。您可以使用 fluent api 来准确配置您想要的内容。解决问题的最简单方法是使用 EF 功能约定优于配置。基本上，遵循约定，EF 框架将为您完成繁重的工作。我在这里添加了一个配置方法的约定，它至少在我的视觉工作室中运行。我已经对此进行了测试，并且运行成功。

public class Bookmark
{
   public int BookmarkID { get; set; }
   public string Url { get; set; }
   public ApplicationUser UserId { get; set; }
   public virtual ICollection<BookmarkTag> BookmarkTags { get; set; }
 }

 public class BookmarkTag
 {
    public int BookmarkTagID { get; set; }
    public virtual Bookmark Bookmark { get; set; }
    public virtual Tag Tag { get; set; }
 }

 public class Tag
 {
    public int TagID { get; set; }
    public string TagName { get; set; }
    public virtual ICollection<BookmarkTag> BookmarkTags { get; set; }
 }