以下代码引发了此错误：
从物化“System.Int16”类型到“System.String”类型的指定强制转换无效
当我删除ToList()时，它不会出现此错误。
var rmas = (
from o in db.Orders
join od in db.OrderDetails on o.OrderNumber equals od.OrderNumber
join r in db.RMAs on o.OrderNumber equals r.OrderNumber
join rd in db.RMADetails on r.RMANumber equals rd.RMANumber
where (rd.WrongSKU == od.SKU)
join i in db.Inventory on od.SKU equals i.LocalSKU into grp
from g in grp.DefaultIfEmpty()
select new
{
r.RMANumber,
r.Reason,
o.Name,
o.Company,
o.Address,
o.Address2,
o.City,
o.State,
o.Country,
o.Email,
o.Zip,
o.Phone,
o.ShipName,
o.ShipCompany,
o.ShipAddress,
o.ShipAddress2,
o.ShipCity,
o.ShipCountry,
o.ShipState,
o.ShipPhone,
o.ShipZip,
o.OrderNumber,
o.ShippingTotal,
o.BalanceDue,
r.Status,
OrderDate = o.OrderDate,
DateIssued = r.DateIssued,
SerialNumbers = rd.SerialNumbers ?? "",
o.SourceOrderID,
od.SKU,
od.ItemNumber,
QTYOrdered = od.QuantityOrdered,
od.QuantityReturned,
rd.QuantityAuthorized,
RMA_ItemNumber1 = rd.ItemNumber,
rd.Price,
rd.WrongSKU,
g.Text1,
CostPerUnit = od.CostPerUnit == null ? 0.0M : od.CostPerUnit
}
).Take(50).ToList();
下面给出的堆栈跟踪：
[InvalidOperationException: The specified cast from a materialized 'System.Int16' type to the 'System.String' type is not valid.]
System.Data.Common.Internal.Materialization.ErrorHandlingValueReader`1.GetValue(DbDataReader reader, Int32 ordinal) +337
System.Data.Common.Internal.Materialization.Shaper.GetColumnValueWithErrorHandling(Int32 ordinal) +57
lambda_method(Closure , Shaper ) +772
System.Data.Common.Internal.Materialization.Coordinator`1.ReadNextElement(Shaper shaper) +170
System.Data.Common.Internal.Materialization.SimpleEnumerator.MoveNext() +84
System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) +327
System.Linq.Enumerable.ToList(IEnumerable`1 source) +58
XME.Controllers.ListController.Index() in C:\User\Me\XMENew\XME\XME\Controllers\ListController.cs:33
lambda_method(Closure , ControllerBase , Object[] ) +96
System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +51
System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +409
System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +52
System.Web.Mvc.Async.AsyncControllerActionInvoker.InvokeSynchronousActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +45
System.Web.Mvc.Async.<>c__DisplayClass42.<BeginInvokeSynchronousActionMethod>b__41() +64
System.Web.Mvc.Async.<>c__DisplayClass8`1.<BeginSynchronous>b__7(IAsyncResult _) +39
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +128
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +94
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +44
System.Web.Mvc.Async.<>c__DisplayClass39.<BeginInvokeActionMethodWithFilters>b__33() +112
System.Web.Mvc.Async.<>c__DisplayClass4f.<InvokeActionMethodFilterAsynchronously>b__49() +325
System.Web.Mvc.Async.<>c__DisplayClass37.<BeginInvokeActionMethodWithFilters>b__36(IAsyncResult asyncResult) +39
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +128
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +94
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +45
System.Web.Mvc.Async.<>c__DisplayClass2a.<BeginInvokeAction>b__20() +50
System.Web.Mvc.Async.<>c__DisplayClass25.<BeginInvokeAction>b__22(IAsyncResult asyncResult) +186
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +128
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +51
System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +40
System.Web.Mvc.<>c__DisplayClass1d.<BeginExecuteCore>b__18(IAsyncResult asyncResult) +40
System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +47
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +140
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +54
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +47
System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +47
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +140
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +54
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +39
System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +39
System.Web.Mvc.<>c__DisplayClass8.<BeginProcessRequest>b__3(IAsyncResult asyncResult) +48
System.Web.Mvc.Async.<>c__DisplayClass4.<MakeVoidDelegate>b__3(IAsyncResult ar) +47
System.Web.Mvc.Async.WrappedAsyncResult`1.End() +140
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +54
System.Web.Mvc.Async.AsyncResultWrapper.End(IAsyncResult asyncResult, Object tag) +40
System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +40
System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +38
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +8862381
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +184
答案 0 :(得分：1)
DB和EF之间ItemNumber的差异是原因。
通过查看您指定的所有值，我从您的陈述中找到了一些线索。
因此只留下一个可能的选项 - ItemNumber :)希望这有帮助。