我遇到了一个问题，当我试图用oftype（）方法对我的odata服务执行linq查询时，我得到一个错误，说请求对版本2服务无效。我已经创建了wcf数据服务，并将maxprotocolversion设置为v3。
public class TestDirectorySearch : DataService<TestDirectoryEntities>
{
public static void InitializeService(DataServiceConfiguration config)
{
config.SetEntitySetAccessRule("*", EntitySetRights.AllRead);
config.SetEntitySetPageSize("*", 50);
config.UseVerboseErrors = true;
config.DataServiceBehavior.MaxProtocolVersion = System.Data.Services.Common.DataServiceProtocolVersion.V3;
}
}
我的edmx有以下行：
<edmx:DataServices m:DataServiceVersion="1.0"
m:MaxDataServiceVersion="3.0"
xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata">
当我尝试执行以下查询时，我得到一个错误，说“当maxprotocolversion小于“3.0”时，不支持方法‘oftype’。”
from test in context.Tests.OfType<OrderableTest>()
where test.TestRevisionId.Equals(mmt.RevisionId)
select new
{
Reflex = test.ReflexTest
, ShipTemp = (test.SpecimenTemperature == null) ? null : test.SpecimenTemperature.DisplayDescription
}).FirstOrDefault();
如果我检查上下文的maxprotocolversion，它将被设置为v2。什么时候会失败？我该怎么做才能正确设置？
准确错误：
{“当maxprotocolversion小于'3.0'时，不支持方法'oftype'。”
请求的堆栈跟踪：
at System.Data.Services.Client.ResourceBinder.AnalyzeOfType(MethodCallExpression mce, DataServiceProtocolVersion maxProtocolVersion)
at System.Data.Services.Client.ResourceBinder.VisitMethodCall(MethodCallExpression mce)
at System.Data.Services.Client.ALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.DataServiceALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.ALinqExpressionVisitor.VisitExpressionList(ReadOnlyCollection`1 original)
at System.Data.Services.Client.ALinqExpressionVisitor.VisitMethodCall(MethodCallExpression m)
at System.Data.Services.Client.ResourceBinder.VisitMethodCall(MethodCallExpression mce)
at System.Data.Services.Client.ALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.DataServiceALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.ResourceBinder.AnalyzeProjection(MethodCallExpression mce, SequenceMethod sequenceMethod, Expression& e)
at System.Data.Services.Client.ResourceBinder.VisitMethodCall(MethodCallExpression mce)
at System.Data.Services.Client.ALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.DataServiceALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.ALinqExpressionVisitor.VisitExpressionList(ReadOnlyCollection`1 original)
at System.Data.Services.Client.ALinqExpressionVisitor.VisitMethodCall(MethodCallExpression m)
at System.Data.Services.Client.ResourceBinder.VisitMethodCall(MethodCallExpression mce)
at System.Data.Services.Client.ALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.DataServiceALinqExpressionVisitor.Visit(Expression exp)
at System.Data.Services.Client.ResourceBinder.Bind(Expression e, DataServiceContext context)
at System.Data.Services.Client.DataServiceQueryProvider.Translate(Expression e)
at System.Data.Services.Client.DataServiceQuery`1.Translate()
at System.Data.Services.Client.DataServiceQuery`1.Execute()
at System.Data.Services.Client.DataServiceQuery`1.GetEnumerator()
at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source)
at System.Data.Services.Client.DataServiceQueryProvider.ReturnSingleton[TElement](Expression expression)
at System.Data.Services.Client.DataServiceQueryProvider.Execute[TResult](Expression expression)
at System.Linq.Queryable.FirstOrDefault[TSource](IQueryable`1 source)
at TDMixBLL.TestDirectoryServiceHandler.PopulateOrderableTestInfo(MonitoredMixTest mmt) in C:\Dev\TDMix\ANSR - TDMix\TDMix2\TDMixBLL\TDMixBLL\TestDirectoryServiceHandler.cs:line 161
at TDMixBLL.TestDirectoryServiceHandler.PopulateTestInfo(MonitoredMixTest test) in C:\Dev\TDMix\ANSR - TDMix\TDMix2\TDMixBLL\TDMixBLL\TestDirectoryServiceHandler.cs:line 124
at TDMixBLL.TestDirectoryServiceHandler.GetTest(Int64 testRevisionId) in C:\Dev\TDMix\ANSR - TDMix\TDMix2\TDMixBLL\TDMixBLL\TestDirectoryServiceHandler.cs:line 112
at TDMixBLL.TestDirectoryServiceHandler.PopulateTests(List`1 testsToPopulate) in C:\Dev\TDMix\ANSR - TDMix\TDMix2\TDMixBLL\TDMixBLL\TestDirectoryServiceHandler.cs:line 66
at TDMix2.Tests.TestRetrievalTests.TestPopulate() in C:\Dev\TDMix\ANSR - TDMix\TDMix2\TDMix2.Tests\TestRetrievalTests.cs:line 38
最佳答案
这是客户端上的错误。为了支持v3特性（比如oftype），dataservicecontext必须使用v3构建。dataservicecontext有一个新的构造函数重载，它接受maxprotocolversion参数。确保使用它并传入v3。