Distinct Records

Hi Jignesh

  It is givine error DistinctBy does not exist in current context. I want distinct by Student id. I want to display studentid,name,mobileno

Thanks

Hello Ramco,

If you want to do distinct  by multiple column then you can create extention method as below,

public static IEnumerable DistinctBy
    (this IEnumerable source, Func keySelector)
{
    HashSet seenKeys = new HashSet();
    foreach (TSource element in source)
    {
        if (seenKeys.Add(keySelector(element)))
        {
            yield return element;
        }
    }
}

You can use as below in your code,

public List GetStudentsByMentor(Int32 MentorId)
        {
            List Result = (from t in 
                                                context.View_SessionDeliveryCalendarDetails_Students 
                                                where (MentorId != 0 ? t.MentorID == MentorId : 1 ==1)
                                                 select t).DistinctBy(d => new { d.MentorId, 
                                                 d.MentorName }).ToList();

            return Result;
        }

Hi

  It is giving error - Cannot implicitly convert system.collections.gereric.list to system.collections.gereric.list

public List GetStudentsByMentor(Int32 MentorId)
        {
            List Result = (from t in context.View_SessionDeliveryCalendarDetails_Students
                                                                        where (MentorId != 0 ? t.MentorID == MentorId : 1 == 1)
                                                                        select t.StudentID).Distinct().ToList();
            foreach (View_SessionDeliveryCalendarDetails_Student item in Result)
            {
                item.Name = item.Name + " - " + item.MobileNo;

            }
            
            return Result;
        }

Thanks

public List GetDistinctStudentIdsByMentor(int mentorId)
{
    var result = (from t in context.View_SessionDeliveryCalendarDetails_Students
                  where (mentorId != 0 ? t.MentorID == mentorId : 1 == 1)
                  select t.StudentID).Distinct().ToList();

    return result;
}

Hi Amit

  Sorry i want distinct to be by StudentId

Thanks

Try this

public List GetStudentsByMentor(Int32 MentorId)
{
    List Result = (from t in context.View_SessionDeliveryCalendarDetails_Students
                                                                where (MentorId != 0 ? t.MentorID == MentorId : 1 == 1)
                                                                select t).Distinct().ToList();

    return Result;
}