C# 尝试使用SingleOrDefault避免空引用
我有一个查询,它是从两个实体连接而来的C# 尝试使用SingleOrDefault避免空引用,c#,ef-code-first,C#,Ef Code First,我有一个查询,它是从两个实体连接而来的 .GroupJoin(uow.Airports.List(),fbm=>fbm.FlyBillMains.AirPortId_Arrival,arr=>arr.AirPortId,(fbm,arr)=>new FlyBillMainDetails { BranchName = fbm.BranchName, C
.GroupJoin(uow.Airports.List(),fbm=>fbm.FlyBillMains.AirPortId_Arrival,arr=>arr.AirPortId,(fbm,arr)=>new FlyBillMainDetails
{
BranchName = fbm.BranchName,
CompanyCode = fbm.CompanyCode,
CompanyName = fbm.CompanyName,
CustomerName = fbm.CustomerName,
FlyBillMains = fbm.FlyBillMains,
PayTypeName = fbm.PayTypeName,
PolicyCode = fbm.PolicyCode,
CountryName = fbm.CountryName,
AirportNameArrival=arr.SingleOrDefault().Name,
Address = fbm.Address,
ShipperName = fbm.ShipperName,
ShipperAddress = fbm.ShipperAddress,
ShipperPhone = fbm.ShipperPhone,
ConsigeeName = fbm.ConsigeeName,
ConsigeeAddress = fbm.ConsigeeAddress,
ConsigeePhone = fbm.ConsigeePhone
})
在这一行
AirportNameArrival=arr.SingleOrDefault().Name
如果AirportNameArrival为空,我就得到了空引用
知道AirportNameArrival是字符串,您可以使用:
默认情况下,您还可以将其与组合以获取空字符串:
string AirportNameArrival = arr.SingleOrDefault()?.Name??"";
您可以使用:
默认情况下,您还可以将其与组合以获取空字符串:
string AirportNameArrival = arr.SingleOrDefault()?.Name??"";
是空引用已修复,但空值不显示在list@haithamsha您更喜欢
”
而不是null
???
是否有帮助?是的,已修复空引用,但空值不显示在list@haithamsha您更喜欢”
而不是null
??
能帮上忙吗?不,我很困惑,工作很好:)不,我很困惑,工作很好:)