c# - 与 System.Linq.IQueryable 结合得到错误

Question

我正在尝试按如下方式使用联合:

var query1 = from c in dc.Hotel_Meals_TBLs
             where c.CHDLunch != "0" && c.CHDLunch != ""
             select new
             {
                 SERVICE_CODE = c.HotelCodeID,
                 SERVICE_NAME = c.HotelName,
                 ROOM_CATEGORY = "",
                 ROOM_TYPE = "",
                 VARIANCE_NAME = "CHILDLUNCH",
                 MARKET = "WW",
                 CONTRACT_BUSINESS_YEAR = "2014/2015",
                 CONTRACT_START_DATE = "01/11/2014",
                 CONTRACT_END_DATE = "30/10/2015",
                 TYPE = "CHILD POLICY",
                 CURRENCY = c.CurrencyCode,
                 PERIOD_NAME = "",
                 PERIOD_START_DATE = "",
                 PERIOD_END_DATE = "",
                 PRICE = c.Lunch,
                 PERCENTAGE = c.CHDLunch + "%",
                 NUM_TO_STAY = "",
                 NUM_TO_PAY = "",
                 PENALTY_TIME_LIMIT = "",
                 PENALTY_NO_DAY_BEFORE = "",
                 CHILD_REFERENCE = "",
                 TEXT = c.ChildPolicy
             };
var query2 = from c in dc.Hotel_Meals_TBLs
             from d in dc.HotelPeriod_TBLs
             from f in dc.HotelRoom_TBLs
             where c.HotelCodeID == d.HotelCodeID && c.HotelCodeID == f.HotelCodeID && f.DBL_HighSeason != 0 && d.PeriodName == "High"
             select new
             {
                 SERVICE_CODE = c.HotelCodeID,
                 SERVICE_NAME = c.HotelName,
                 ROOM_CATEGORY = f.RoomName,
                 ROOM_TYPE = "DBL",
                 VARIANCE_NAME = "",
                 MARKET = "WW",
                 CONTRACT_BUSINESS_YEAR = "2014/2015",
                 CONTRACT_START_DATE = "01/11/2014",
                 CONTRACT_END_DATE = "30/10/2015",
                 TYPE = "COST",
                 CURRENCY = c.CurrencyCode,
                 PERIOD_NAME = d.PeriodName,
                 PERIOD_START_DATE = d._From,
                 PERIOD_END_DATE = d._To,
                 PRICE = f.SGL_LowSeason,
                 PERCENTAGE = "",
                 NUM_TO_STAY = "",
                 NUM_TO_PAY = "",
                 PENALTY_TIME_LIMIT = "",
                 PENALTY_NO_DAY_BEFORE = "",
                 CHILD_REFERENCE = "",
                 TEXT = ""
             };
 var result = query1.Union(query2);

我得到了这个错误:

'System.Linq.IQueryable<AnonymousType#1>' does not contain a definition for 'Union' and the best extension method overload 'System.Linq.ParallelEnumerable.Union<TSource>(System.Linq.ParallelQuery<TSource>, System.Collections.Generic.IEnumerable<TSource>)' has some invalid arguments

Instance argument: cannot convert from 'System.Linq.IQueryable<AnonymousType#1>' to 'System.Linq.ParallelQuery<AnonymousType#2>'

真的，我多次使用这个方法，没有出现错误......你知道这个查询有什么问题吗？

Answer 1

错误消息表明 .NET 认为这两种匿名类型不同。为了使两个匿名类型相同，它们必须具有相同数量的具有相同名称和类型的属性。我查看了您的属性(property) list ，它们似乎以相同的顺序具有相同的名称。但是，您可能在这些方面有不同的类型:

类型 1

PERIOD_START_DATE = ""
PERIOD_END_DATE = ""
PRICE = c.Lunch,
TEXT = c.ChildPolicy

类型 2

PERIOD_START_DATE = d._From
PERIOD_END_DATE = d._To
PRICE = f.SGL_LowSeason
TEXT = ""

确保 d._From、d._To 和 c.ChildPolicy 都是字符串并且 c.Lunch 和 f.SGL_LowSeason 是同一类型(例如，可能一个是 int，另一个是 decimal)。