Question

我创建了一个restful服务，它返回一个List实体类型：

    [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
[ServiceBehavior(IncludeExceptionDetailInFaults = true)]
public class RealAgent : IRealAgent 
{
    public IList<RealUser> GetAll()
    {
        return UserManager.Agents();
    }
    }

//用户管理器类实现

    public static List<RealUser> Agents()
    {
        var q = from x in DBContextHelper.DBContext.RealUsers
                orderby x.CreatedOn descending
                select new RealUser()
                        {
                                            FirstName = x.FirstName,
                                            LastName =x.LastName,
                                            AboutProfession = x.AboutProfession
                        };

        return q.ToList();
    }

//我正在获取所选列。但它没有用。我是否需要创建自己的类OR是否可以使用Entity Framework实现？

错误：服务器遇到处理请求的错误。 LINQ to Entities查询中无法构造异常消息'实体或复杂类型'GharbarIndia.Data.RealUser'。请参阅服务器日志以获取更多详异常堆栈跟踪是：

System.Data.Objects.ELinq.ExpressionConverter上System.Data.Objects.ELinq.ExpressionConverter.MemberInitTranslator.TypedTranslate（ExpressionConverter parent，MemberInitExpression linq）中的System.Data.Objects.ELinq.ExpressionConverter.CheckInitializerType（Type type）的

.TypedTranslator 1.Translate(ExpressionConverter parent, Expression linq) at System.Data.Objects.ELinq.ExpressionConverter.TranslateExpression(Expression linq) at System.Data.Objects.ELinq.ExpressionConverter.TranslateLambda(LambdaExpression lambda, DbExpression input) at System.Data.Objects.ELinq.ExpressionConverter.TranslateLambda(LambdaExpression lambda, DbExpression input, DbExpressionBinding& binding) at System.Data.Objects.ELinq.ExpressionConverter.MethodCallTranslator.OneLambdaTranslator.Translate(ExpressionConverter parent, MethodCallExpression call, DbExpression& source, DbExpressionBinding& sourceBinding, DbExpression& lambda) at System.Data.Objects.ELinq.ExpressionConverter.MethodCallTranslator.SelectTranslator.Translate(ExpressionConverter parent, MethodCallExpression call) at System.Data.Objects.ELinq.ExpressionConverter.MethodCallTranslator.SequenceMethodTranslator.Translate(ExpressionConverter parent, MethodCallExpression call, SequenceMethod sequenceMethod) at System.Data.Objects.ELinq.ExpressionConverter.MethodCallTranslator.TypedTranslate(ExpressionConverter parent, MethodCallExpression linq) at System.Data.Objects.ELinq.ExpressionConverter.TypedTranslator 1.在System.Data.Objects.ELinq.ExpressionConverter.TranslateExpression（Expression linq）上的System.Data.Objects.ELinq.ExpressionConverter.Convert（）中转换（ExpressionConverter parent，Expression linq）。 Data.Objects.ELinq.ELinqQueryState.GetExecutionPlan（Nullable 1 forMergeOption) at System.Data.Objects.ObjectQuery 1.GetResults（Nullable 1 forMergeOption) at System.Data.Objects.ObjectQuery 1.System.Collections.Generic.IEnumerable.GetEnumerator（）at System.Collections.Generic.List {{1 System.Linq.Enumerable.ToList [TSource]（IEnumerable`1 source）在E：\ Gharbarindia \ Dev \ GharbarIndia.Data \ User \ UserManager中的GharbarIndia.Data.User.UserManager.Agents（）中的1个集合。 cs：位于E：\ Gharbarindia \ Dev \ GharbarIndia.ServiceCore \ RealAgent.cs：GharbarIndia.ServiceCore.RealAgent.GetAll（）的第179行16在SyncInvokeGetAll（Object，Object []，Object []）处于System.ServiceModel.Dispatcher.SyncMethodInvoker.Invoke（Object instance，Object [] inputs，Object []＆amp; System.ServiceModel.Dispatcher.DispatchOperationRuntime.InvokeBegin（MessageRpc＆amp; rpc）的System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage5（MessageRpc＆amp; rpc）位于System的System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage41（MessageRpc＆amp; rpc）。 ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage4（MessageRpc＆安培; RPC）在System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage31（MessageRpc＆安培; RPC）在System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage3（MessageRpc＆安培; RPC）在System.ServiceModel.Dispatcher.ImmutableDispatchRuntime位于System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage1（MessageRpc＆amp; rpc）的System.ServiceModel.Dispatcher.ImmutableDispatchRuntime.ProcessMessage11（MessageRpc＆amp; rpc）上的.ProcessMessage2（MessageRpc＆amp; rpc），位于System.ServiceModel.Dispatcher.MessageRpc.Process（Boolean isOperationContextSet））

Answer 1

您无法投影到实体。尝试创建一个只包含您需要选择的字段的新类。

public class MyRealUser
{
    public string FirstName { get; set; }
    public string LastName { get; set; }
    public string AboutProfession { get; set; }
}

var q = from x in DBContextHelper.DBContext.RealUsers
    orderby x.CreatedOn descending
    select new MyRealUser()
    {
        FirstName = x.FirstName,
        LastName =x.LastName,
        AboutProfession = x.AboutProfession
    };

linq到sql列表，其中包含Restful service中的选定列

1 个答案: