实体框架code第一对象引用不设置到对象的实例 [英] Entity Framework code first Object reference not set to an instance of an object

问题描述

我收到以下错误，当我尝试首先使用EF code，

 对象引用未设置到对象的实例。
 

我得到这个，当我尝试运行例如像收取任何查询 db.Surveys.ToList（）。我也曾尝试运行启用迁移命令，给出了同样的错误。
我的web应用程序是asp.net web窗体和我使用EFv6.1.1（最新的）。
我还添加了在我的web.config上下文名称的连接字符串。

我一直在使用的EntityFramework的年龄和从未有过这个问题，任何帮助是pciated AP $ P $

堆栈跟踪

  System.NullReferenceException：对象不设置到对象的实例。
   在System.Web.UI.ParseChildrenAttribute.GetHash code（）
   在System.Collections.Generic.ObjectEqualityComparer`1.GetHash code（T OBJ）
   在System.Collections.Generic.HashSet`1.InternalGetHash code（T项）
   在System.Collections.Generic.HashSet`1.AddIfNot present（T值）
   在System.Collections.Generic.HashSet`1.UnionWith（IEnumerable`1等）
   在System.Collections.Generic.HashSet`1..ctor（IEnumerable`1收集，IEqualityComparer`1比较器）
   在System.Data.Entity.ModelConfiguration.Utilities.AttributeProvider.GetAttributes（type类型）
   在System.Data.Entity.ModelConfiguration.Utilities.AttributeProvider.<>c__DisplayClass4.<GetAttributes>b__3(PropertyInfo PI）
   在System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd（TKEY的关键，Func`2 valueFactory）
   在System.Data.Entity.ModelConfiguration.Utilities.AttributeProvider.GetAttributes（的PropertyInfo的PropertyInfo）
   在System.Data.Entity.ModelConfiguration.Conventions.PropertyAttributeConfigurationConvention`1.<.ctor>b__0(ConventionTypeConfiguration EC）
   在System.Data.Entity.ModelConfiguration.Conventions.TypeConvention.ApplyCore（类型的MemberInfo，ModelConfiguration modelConfiguration）
   在System.Data.Entity.ModelConfiguration.Conventions.TypeConventionBase.Apply（类型的MemberInfo，ModelConfiguration modelConfiguration）
   在System.Data.Entity.ModelConfiguration.Configuration.ConventionsConfiguration.ApplyModelConfiguration(Type类型，ModelConfiguration modelConfiguration）
   在System.Data.Entity.ModelConfiguration.Conventions.Convention.ApplyModelConfiguration（类型类型，ModelConfiguration modelConfiguration）
   在System.Data.Entity.ModelConfiguration.Configuration.ConventionsConfiguration.ApplyModelConfiguration(Type类型，ModelConfiguration modelConfiguration）
   在System.Data.Entity.ModelConfiguration.Mappers.TypeMapper.MapEntityType（type类型）
   在System.Data.Entity.DbModelBuilder＆LT;方式＆gt;＆c__DisplayClassd LT;地图类型＆GT; b__7（类型类型）
   在System.Linq.Enumerable.WhereListIterator`1.MoveNext（）
   在System.Data.Entity.Utilities.IEnumerableExtensions.Each [T]（IEnumerable`1 TS，Action`1动作）
   在System.Data.Entity.DbModelBuilder.MapTypes（EdmModel模型）
   在System.Data.Entity.DbModelBuilder.Build（DbProviderManifest providerManifest，DbProviderInfo providerInfo）
   在System.Data.Entity.DbModelBuilder.Build（的DbConnection providerConnection）
   在System.Data.Entity.Internal.LazyInternalContext.CreateModel（LazyInternalContext internalContext）
   在System.Data.Entity.Internal.RetryLazy`2.GetValue（TInput输入）
   在System.Data.Entity.Internal.LazyInternalContext.InitializeContext（）
   在System.Data.Entity.Internal.LazyInternalContext.get_ModelBeingInitialized（）
   在System.Data.Entity.Infrastructure.EdmxWriter.WriteEdmx（的DbContext背景下，XmlWriter的作家）
   在System.Data.Entity.Utilities.DbContextExtensions.<>c__DisplayClass1.<GetModel>b__0(XmlWriter W）
   在System.Data.Entity.Utilities.DbContextExtensions.GetModel（Action`1中WriteXML）
   在System.Data.Entity.Utilities.DbContextExtensions.GetModel（的DbContext上下文）
   在System.Data.Entity.Migrations.DbMigrator..ctor（DbMigrationsConfiguration配置的DbContext usersContext，DatabaseExistenceState existenceState，布尔calledByCreateDatabase）
   在System.Data.Entity.Migrations.DbMigrator..ctor（DbMigrationsConfiguration配置）
   在System.Data.Entity.Migrations.Design.MigrationScaffolder..ctor（DbMigrationsConfiguration migrationsConfiguration）
   在System.Data.Entity.Migrations.Design.ToolingFacade.ScaffoldRunner.Run（）
   在System.AppDomain.DoCallBack（CrossAppDomainDelegate callBackDelegate）
   在System.AppDomain.DoCallBack（CrossAppDomainDelegate callBackDelegate）
   在System.Data.Entity.Migrations.Design.ToolingFacade.Run（跑垒员亚军）
   在System.Data.Entity.Migrations.Design.ToolingFacade.ScaffoldInitialCreate（String语言，字符串rootNamespace）
   在System.Data.Entity.Migrations.EnableMigrationsCommand＆LT;方式＆gt;＆c__DisplayClass2 LT; .ctor＆GT; b__0（）
   在System.Data.Entity.Migrations.MigrationsDomainCommand.Execute（动作命令）
 

解决方案

我找到了答案。

我错过了加入公众诠释标识{搞定;组; } 我的对象之一，显然实体框架不喜欢那场。

I get the following error when I try to use EF code first,

Object reference not set to an instance of an object.

I get this when I try to run ANY query on a collection like e.g. db.Surveys.ToList(). I have also tried to run the Enable Migrations command, gives the same error. My web app is asp.net web forms and I am using EFv6.1.1 (latest). I have also added a connection string with the context name in my web.config.

I have been using Entityframework for ages and never had this issue, any help is appreciated

Stacktrace

System.NullReferenceException: Object reference not set to an instance of an object.
   at System.Web.UI.ParseChildrenAttribute.GetHashCode()
   at System.Collections.Generic.ObjectEqualityComparer`1.GetHashCode(T obj)
   at System.Collections.Generic.HashSet`1.InternalGetHashCode(T item)
   at System.Collections.Generic.HashSet`1.AddIfNotPresent(T value)
   at System.Collections.Generic.HashSet`1.UnionWith(IEnumerable`1 other)
   at System.Collections.Generic.HashSet`1..ctor(IEnumerable`1 collection, IEqualityComparer`1 comparer)
   at System.Data.Entity.ModelConfiguration.Utilities.AttributeProvider.GetAttributes(Type type)
   at System.Data.Entity.ModelConfiguration.Utilities.AttributeProvider.<>c__DisplayClass4.<GetAttributes>b__3(PropertyInfo pi)
   at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory)
   at System.Data.Entity.ModelConfiguration.Utilities.AttributeProvider.GetAttributes(PropertyInfo propertyInfo)
   at System.Data.Entity.ModelConfiguration.Conventions.PropertyAttributeConfigurationConvention`1.<.ctor>b__0(ConventionTypeConfiguration ec)
   at System.Data.Entity.ModelConfiguration.Conventions.TypeConvention.ApplyCore(Type memberInfo, ModelConfiguration modelConfiguration)
   at System.Data.Entity.ModelConfiguration.Conventions.TypeConventionBase.Apply(Type memberInfo, ModelConfiguration modelConfiguration)
   at System.Data.Entity.ModelConfiguration.Configuration.ConventionsConfiguration.ApplyModelConfiguration(Type type, ModelConfiguration modelConfiguration)
   at System.Data.Entity.ModelConfiguration.Conventions.Convention.ApplyModelConfiguration(Type type, ModelConfiguration modelConfiguration)
   at System.Data.Entity.ModelConfiguration.Configuration.ConventionsConfiguration.ApplyModelConfiguration(Type type, ModelConfiguration modelConfiguration)
   at System.Data.Entity.ModelConfiguration.Mappers.TypeMapper.MapEntityType(Type type)
   at System.Data.Entity.DbModelBuilder.<>c__DisplayClassd.<MapTypes>b__7(Type type)
   at System.Linq.Enumerable.WhereListIterator`1.MoveNext()
   at System.Data.Entity.Utilities.IEnumerableExtensions.Each[T](IEnumerable`1 ts, Action`1 action)
   at System.Data.Entity.DbModelBuilder.MapTypes(EdmModel model)
   at System.Data.Entity.DbModelBuilder.Build(DbProviderManifest providerManifest, DbProviderInfo providerInfo)
   at System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection)
   at System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext)
   at System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input)
   at System.Data.Entity.Internal.LazyInternalContext.InitializeContext()
   at System.Data.Entity.Internal.LazyInternalContext.get_ModelBeingInitialized()
   at System.Data.Entity.Infrastructure.EdmxWriter.WriteEdmx(DbContext context, XmlWriter writer)
   at System.Data.Entity.Utilities.DbContextExtensions.<>c__DisplayClass1.<GetModel>b__0(XmlWriter w)
   at System.Data.Entity.Utilities.DbContextExtensions.GetModel(Action`1 writeXml)
   at System.Data.Entity.Utilities.DbContextExtensions.GetModel(DbContext context)
   at System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration configuration, DbContext usersContext, DatabaseExistenceState existenceState, Boolean calledByCreateDatabase)
   at System.Data.Entity.Migrations.DbMigrator..ctor(DbMigrationsConfiguration configuration)
   at System.Data.Entity.Migrations.Design.MigrationScaffolder..ctor(DbMigrationsConfiguration migrationsConfiguration)
   at System.Data.Entity.Migrations.Design.ToolingFacade.ScaffoldRunner.Run()
   at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
   at System.AppDomain.DoCallBack(CrossAppDomainDelegate callBackDelegate)
   at System.Data.Entity.Migrations.Design.ToolingFacade.Run(BaseRunner runner)
   at System.Data.Entity.Migrations.Design.ToolingFacade.ScaffoldInitialCreate(String language, String rootNamespace)
   at System.Data.Entity.Migrations.EnableMigrationsCommand.<>c__DisplayClass2.<.ctor>b__0()
   at System.Data.Entity.Migrations.MigrationsDomainCommand.Execute(Action command)

解决方案

I found the answer.

I missed adding the public int Id {get; set; } field on one of my objects and apparently Entity Framework doesn't like that.

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