Question

我正在尝试使用union如下：

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>'不包含'Union'的定义，并且最佳扩展方法重载'System.Linq.ParallelEnumerable.Union<TSource>(System.Linq.ParallelQuery<TSource>, System.Collections.Generic.IEnumerable<TSource>)'有一些无效的参数

实例参数：无法从'System.Linq.IQueryable<AnonymousType#1>'转换为'System.Linq.ParallelQuery<AnonymousType#2>'

真的我多次使用这种方法而没有出错...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。我已经浏览了你的属性列表，它们看起来在同一个顺序中具有相同的名称。但是，您可能在这些方面有不同的类型：

输入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，且c.Lunch和f.SGL_LowSeason属于同一类型（例如，可能是一个int，另一个是decimal）。

Answer 2

您必须创建一个包含所需属性的ViewModel，并将所有值分配给viewmodel属性，并且在查询中select语句将如下：

select new ViewModel{
    ViewmodelProperties = Value,
};

像：

var query1 = from c in dc.Hotel_Meals_TBLs
         where c.CHDLunch != "0" && c.CHDLunch != ""
         select new ViewModel
         {
             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 ViewModel
         {
             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);

与System.Linq.IQueryable的联合获取错误

2 个答案: