在linq查询中获取计数

Question

i want to get count in linq query its work fine without comparing date in where condition but after comparing date it gives exception.

public static IList GetAllCategoryData()
{
     using (var objEntity = new BlueCouponEntities())
     {
       return (from TBL in objEntity.CategoryMasters.AsEnumerable()
                 let IIT = TBL.CategoryImageTransactions
                 select new
                 {
                 TBL.CategoryID,
                 TBL.CategoryName,
                 CategoryCount = objEntity.OfferCategoryMasters.Where(Lg => Lg.CategoryID == TBL.CategoryID && Lg.OfferMaster.EndDate > DateTime.Now.Date).Count(),
                 }
             ).ToList();
     }
}

Error is : The specified type member ;Date; is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported.

Answer 1

You have to use EntityFunctions.TruncateTime to get the Date part of DateTime

using (var objEntity = new BlueCouponEntities())
{
    return (from TBL in objEntity.CategoryMasters.AsEnumerable()
                 let IIT = TBL.CategoryImageTransactions
                 select new
                 {
                 TBL.CategoryID,
                 TBL.CategoryName,
                 CategoryCount = objEntity.OfferCategoryMasters.Where(Lg => Lg.CategoryID == TBL.CategoryID && Lg.OfferMaster.EndDate > EntityFunctions.TruncateTime(DateTime.Now)).Count(),
                 }
             ).ToList();
}

Since DateTime.Now is Constant at the moment, you could also write this

 using (var objEntity = new BlueCouponEntities())
 {
     DateTime now = DateTime.Now.Date;
     return (from TBL in objEntity.CategoryMasters.AsEnumerable()
                 let IIT = TBL.CategoryImageTransactions
                 select new
                 {
                 TBL.CategoryID,
                 TBL.CategoryName,
                 CategoryCount = objEntity.OfferCategoryMasters.Where(Lg => Lg.CategoryID == TBL.CategoryID && Lg.OfferMaster.EndDate > now).Count(),
                 }
             ).ToList();   
}

Answer 2

It has nothing to do with the Count() function. As the exception says, its a DateTime problem. Use DbFunctions.TruncateTime ( EntityFunctions.TruncateTime is deprecated since EF6)

public static IList GetAllCategoryData()
{
     using (var objEntity = new BlueCouponEntities())
     {
       return (from TBL in objEntity.CategoryMasters.AsEnumerable()
                 let IIT = TBL.CategoryImageTransactions
                 select new
                 {
                 TBL.CategoryID,
                 TBL.CategoryName,
                 CategoryCount = objEntity.OfferCategoryMasters.Where(Lg => Lg.CategoryID == TBL.CategoryID && EntityFunctions.TruncateTime(Lg.OfferMaster.EndDate) > EntityFunctions.TruncateTime(DateTime.Now.Date)).Count(),
                 }
             ).ToList();
     }
}

Answer 3

Add following lines:

var today = DateTime.Now.Date;

Then use today instead of DateTime.Now.Date into linq query.