yourDateList.GroupBy(i => i.ToString("yyyyMMdd"))
.Select(i => new
{
Date = DateTime.ParseExact(i.Key, "yyyyMMdd", CultureInfo.InvariantCulture, DateTimeStyles.None),
Count = i.Count()
});
context.Users
.Where((x.LastLogIn >= lastWeek) && (x.LastLogIn <= DateTime.Now))
.GroupBy(x => DbFunctions.TruncateTime(x.LastLogIn))
.Select(x => new
{
Value = x.Count(),
// Replace the commented line
//Day = (DateTime)DbFunctions.TruncateTime(x.Key)
// ...with this line
Day = (DateTime)x.Key
}).ToList();