創建模型時無法使用數據上下文。實體框架5

我想在我的空閒時間創建一個簡單的博客網站的數據結構，我似乎無法弄清楚爲什麼我得到這個錯誤。我正在使用EF5和MVC4。該的DbContext：創建模型時無法使用數據上下文。實體框架5

public class KWBlogContext : DbContext 
{ 
    static KWBlogContext() 
    { 
     Database.SetInitializer<KWBlogContext>(null); 
    } 

    public DbSet<Blog> Blogs { get; set; } 
    public DbSet<BlogType> BlogTypes { get; set; } 

etc...

我嘗試一點與OnModelCreating，但無濟於事。

的的DbContext是由BaseController初始化：

public class BaseController : Controller 
{ 

    public KWBlogContext db; 
    public BaseController() 
    { 
     Database.SetInitializer<KWBlogContext>(null); 
     db = new KWBlogContext(); 
    } 

}

我得到的「序列包含多個元素」在此行中的HomeController錯誤（實現BaseController）：

vm.Blogs = db.Blogs.Where(x => x.CreatedDate >= subtractDate).OrderBy(x => x.BlogId).ToList(); 
vm.BlogTypes = db.BlogTypes.ToList();

這裏是StackTrace：

[InvalidOperationException: Sequence contains more than one element] 
System.Linq.Enumerable.SingleOrDefault(IEnumerable`1 source) +4078798 
System.Data.Entity.ModelConfiguration.Conventions.<>c__DisplayClass3.<System.Data.Entity.ModelConfiguration.Conventions.IEdmConvention<System.Data.Entity.Edm.EdmEntityType>.Apply>b__0(PropertyInfo p) +187 
System.Data.Entity.ModelConfiguration.Utilities.IEnumerableExtensions.Each(IEnumerable`1 ts, Action`1 action) +194 
    System.Data.Entity.ModelConfiguration.Conventions.DeclaredPropertyOrderingConvention.System.Data.Entity.ModelConfiguration.Conventions.IEdmConvention<System.Data.Entity.Edm.EdmEntityType>.Apply(EdmEntityType entityType, EdmModel model) +185 
    System.Data.Entity.ModelConfiguration.Configuration.EdmConventionDispatcher.Dispatch(TEdmDataModelItem item) +181 
    System.Data.Entity.ModelConfiguration.Configuration.EdmConventionDispatcher.VisitEdmEntityType(EdmEntityType item) +59 
    System.Data.Entity.Edm.Internal.DataModelItemVisitor.VisitCollection(IEnumerable`1 collection, Action`1 visitMethod) +204 
    System.Data.Entity.Edm.Internal.EdmModelVisitor.VisitEntityTypes(EdmNamespace edmNamespace, IEnumerable`1 entityTypes) +89 
    System.Data.Entity.Edm.Internal.EdmModelVisitor.VisitEdmNamespace(EdmNamespace item) +193 
    System.Data.Entity.ModelConfiguration.Configuration.EdmConventionDispatcher.VisitEdmNamespace(EdmNamespace item) +53 
    System.Data.Entity.Edm.Internal.DataModelItemVisitor.VisitCollection(IEnumerable`1 collection, Action`1 visitMethod) +204 
    System.Data.Entity.Edm.Internal.EdmModelVisitor.VisitNamespaces(EdmModel model, IEnumerable`1 namespaces) +89 
    System.Data.Entity.Edm.Internal.EdmModelVisitor.VisitEdmModel(EdmModel item) +130 
    System.Data.Entity.ModelConfiguration.Configuration.EdmConventionDispatcher.VisitEdmModel(EdmModel item) +79 
    System.Data.Entity.ModelConfiguration.Configuration.EdmConventionDispatcher.Dispatch() +36 
    System.Data.Entity.ModelConfiguration.Configuration.ConventionsConfiguration.ApplyModel(EdmModel model) +136 
    System.Data.Entity.DbModelBuilder.Build(DbProviderManifest providerManifest, DbProviderInfo providerInfo) +209 
    System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection) +106 
    System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext) +143 
    System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input) +171 
    System.Data.Entity.Internal.LazyInternalContext.InitializeContext() +499 
    System.Data.Entity.Internal.InternalContext.Initialize() +31 
    System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType) +39 
    System.Data.Entity.Internal.Linq.InternalSet`1.Initialize() +137 
    System.Data.Entity.Internal.Linq.InternalSet`1.get_InternalContext() +38 
    System.Data.Entity.Infrastructure.DbQuery`1.System.Linq.IQueryable.get_Provider() +84

任何輸入，將不勝感激。一兩天我一直在毆打我的頭。提前致謝！

編輯：

我已經認識到，它也可能是一個SQL Server /配置問題。我一直在尋找在我Management Studio中的日誌和碰到：

The SQL Server Network Interface library could not register the SPN for the SQL Server service. [ MSSQLSvc/MachineName:SQLEXPRESS] Windows return code: 0xffffffff, state 63 
Dedicated administrator connection support was not started because it has been disabled on this edition of SQL Server. If you want to use dedicated administrator connection, restart SQL server using the trace flag 7806.

這裏是我的connectionString：

<add name="KWBlogContext" connectionString="Data Source=MACHINENAME\SQLEXPRESS;Initial Catalog=KWBlog;Integrated Security=True" providerName="System.Data.SqlClient" />

來源

2013-05-26 kwinsor5

在你的代碼

某處，你已經使用了SingleOrDefault和條件或表達式返回多一個元素。請發佈您的控制器代碼進行驗證。

來源

2013-05-26 12:28:11 Saravanan

我發佈的HomeController代碼是調用DbContext的唯一代碼，它使用ToList（）方法。它在視圖模型中定義爲public IEnumerable Blogs {get;組; } – kwinsor5

你可以請調試，看看當你點擊這條線'db.Blogs.Where（x => x.CreatedDate> = subtractDate）.OrderBy（x => x.BlogId）時正在生成的EF查詢是什麼。 ToList（）;' – Saravanan

創建模型時無法使用數據上下文。實體框架5

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