我收到此错误:
不支持输入类型为“Domain.Flood.Entities.Things.SomeObject”且检查类型为“Domain.Entities.Base”的“TypeIs”表达式。 LINQ to Entities 查询仅支持实体类型和复杂类型。
我正在尝试调用 OData API 并展开对象上的
CreatedBy
属性。 CreatedBy
属性位于基类中,是 User
的类型。所以我的基类看起来像这样:
[DataContract(Namespace = "http://schemas.microsoft.com/ado/2007/08/dataservices")]
public abstract class Base
{
[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[DataMember]
public int Id { get; set; }
[DataMember]
public string Name { get; set; }
[DataMember]
public string Description { get; set; }
private User createdBy;
[DataMember]
public virtual User CreatedBy
{
get
{
return createdBy;
}
set
{
createdBy = value;
}
}
}
当我尝试获取从基类继承的小部件,并且我还想包含名为
User
的 CreatedBy
对象时,我收到此错误。如果我不展开 CreatedBy
对象,我就不会收到错误。这是奇怪的部分,我有另一个 User 属性不在基类上,而是在我的 SomeObject
类中,称为 AssignedTo
。如果我扩展这一点,一切都是美好的。因此,在基类上扩展 User 对象,没有效果。将 User 对象向上扩展几个级别,bueno。
{
Container.SendingRequest += new EventHandler<SendingRequestEventArgs>(OnSendingRequest);
ViewBag.Data = Container.SomeObject.Expand("Address, CreatedBy").ToList();
return View();
}
这是堆栈跟踪:
Exception Details: System.Data.Services.Client.DataServiceClientException: <?xml version="1.0" encoding="utf-8"?>
<m:error xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata">
<m:code />
<m:message xml:lang="en-US">An error has occurred.</m:message>
<m:innererror>
<m:message>The 'ObjectContent`1' type failed to serialize the response body for content type 'application/atom+xml; charset=utf-8'.</m:message>
<m:type>System.InvalidOperationException</m:type>
<m:stacktrace></m:stacktrace>
<m:internalexception>
<m:message>The 'TypeIs' expression with an input of type 'Domain.Flood.Entities.Things.SomeObject' and a check of type 'Domain.Entities.Base' is not supported. Only entity types and complex types are supported in LINQ to Entities queries.</m:message>
<m:type>System.NotSupportedException</m:type>
<m:stacktrace> at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.GetIsOrAsTargetType(ExpressionType operationType, Type toClrType, Type fromClrType)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.IsTranslator.TypedTranslate(ExpressionConverter parent, TypeBinaryExpression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TypedTranslator`1.Translate(ExpressionConverter parent, Expression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TranslateExpression(Expression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.ConditionalTranslator.TypedTranslate(ExpressionConverter parent, ConditionalExpression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TypedTranslator`1.Translate(ExpressionConverter parent, Expression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TranslateExpression(Expression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.MemberInitTranslator.TypedTranslate(ExpressionConverter parent, MemberInitExpression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TypedTranslator`1.Translate(ExpressionConverter parent, Expression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TranslateExpression(Expression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.MemberInitTranslator.TypedTranslate(ExpressionConverter parent, MemberInitExpression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TypedTranslator`1.Translate(ExpressionConverter parent, Expression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TranslateExpression(Expression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.MemberInitTranslator.TypedTranslate(ExpressionConverter parent, MemberInitExpression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TypedTranslator`1.Translate(ExpressionConverter parent, Expression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TranslateExpression(Expression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TranslateLambda(LambdaExpression lambda, DbExpression input)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TranslateLambda(LambdaExpression lambda, DbExpression input, DbExpressionBinding& binding)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.MethodCallTranslator.OneLambdaTranslator.Translate(ExpressionConverter parent, MethodCallExpression call, DbExpression& source, DbExpressionBinding& sourceBinding, DbExpression& lambda)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.MethodCallTranslator.SelectTranslator.Translate(ExpressionConverter parent, MethodCallExpression call)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.MethodCallTranslator.SequenceMethodTranslator.Translate(ExpressionConverter parent, MethodCallExpression call, SequenceMethod sequenceMethod)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.MethodCallTranslator.TypedTranslate(ExpressionConverter parent, MethodCallExpression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TypedTranslator`1.Translate(ExpressionConverter parent, Expression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.TranslateExpression(Expression linq)
at System.Data.Entity.Core.Objects.ELinq.ExpressionConverter.Convert()
at System.Data.Entity.Core.Objects.ELinq.ELinqQueryState.GetExecutionPlan(Nullable`1 forMergeOption)
at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClassb.<GetResults>b__a()
at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClassb.<GetResults>b__9()
at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
at System.Data.Entity.Core.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
at System.Data.Entity.Core.Objects.ObjectQuery`1.<System.Collections.Generic.IEnumerable<T>.GetEnumerator>b__0()
at System.Lazy`1.CreateValue()
at System.Lazy`1.LazyInitValue()
at System.Lazy`1.get_Value()
at System.Data.Entity.Internal.LazyEnumerator`1.MoveNext()
at System.Web.Http.OData.Formatter.Serialization.ODataFeedSerializer.WriteFeed(IEnumerable enumerable, IEdmTypeReference feedType, ODataWriter writer, ODataSerializerContext writeContext)
at System.Web.Http.OData.Formatter.Serialization.ODataFeedSerializer.WriteObjectInline(Object graph, IEdmTypeReference expectedType, ODataWriter writer, ODataSerializerContext writeContext)
at System.Web.Http.OData.Formatter.Serialization.ODataFeedSerializer.WriteObject(Object graph, Type type, ODataMessageWriter messageWriter, ODataSerializerContext writeContext)
at System.Web.Http.OData.Formatter.ODataMediaTypeFormatter.WriteToStream(Type type, Object value, Stream writeStream, HttpContent content, HttpContentHeaders contentHeaders)
at System.Web.Http.OData.Formatter.ODataMediaTypeFormatter.WriteToStreamAsync(Type type, Object value, Stream writeStream, HttpContent content, TransportContext transportContext)
--- End of stack trace from previous location where exception was thrown ---
at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
at System.Runtime.CompilerServices.TaskAwaiter.GetResult()
at System.Web.Http.WebHost.HttpControllerHandler.<WriteBufferedResponseContentAsync>d__14.MoveNext()</m:stacktrace>
</m:internalexception>
</m:innererror>
</m:error>
阅读错误消息,我可以看到 Linq to Entities 正在尝试将一件事转换为另一件事,但到目前为止,我真的不知道。
我注意到的另一件事是我的 OData 元数据显示了所有内容,而不仅仅是具有数据契约的内容。它过去只包含具有数据契约的类。这很奇怪吧?我检查了我的源代码管理来查看最近几个变更集中发生了什么变化,我没有看到任何与我的 Base 类、Users 类或我的
SomeObject
类有关的内容。也与我的 API 无关。
如果我能说得更清楚,请告诉我。我感觉我遗漏了一些东西。
如果您仔细阅读错误:
输入类型为“TypeIs”的表达式 'Domain.Flood.Entities.Things.SomeObject' 和类型检查 不支持“Domain.Entities.Base”。
这意味着 OData 尝试执行一项查询,使 EF 生成一个带有“TypeIs”函数的查询,该函数本身就很好,但 TypeIs 的两个操作数必须是实体类型或复杂类型:
LINQ to Entities 仅支持也就是说,在 EF DbContext 中,使用 ModelBuilder,您必须确保 SomeObject 和 Base 都被上下文视为实体类型或复杂类型。这是使用实体类型 和 复杂类型 查询。
Fluent API 来完成的:
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Base>(); //EF should crawl and configure all derived types as well.
}
另外,使用 DbModelBuilder.Ignore() 时要特别注意不要忽略任何重要类型。
更新:
您还可以使用ODataConventionModelBuilder
:告诉 OData 将所有超类继承的属性视为继承类型自己的属性 与
System.Web.OData
:
modelBuilder.EntityType<SomeObject>().DerivesFromNothing();
与
System.Web.Http.OData
:
modelBuilder.Entity<SomeObject>().DerivesFromNothing();