Converting iQueryable to IEnumerable

Question

What is the problem with my code below? It's not returning any items even when matching records are present in the database. If it's wrong, how can I convert my IQueryable to IEnumerable?

public IEnumerable<TimelineItem> TimeLineItems { get; set; }
public IEnumerable<TimelineItem> GetTimeLineItems(int SelectedPID)
{
    TimeLineItems = (from t in db.TimelineItems
                     where t.ProductID == SelectedPID
                     select new { t.Description, t.Title }) as IEnumerable<TimelineItem>;
    return TimeLineItems;
}

score 19 · Accepted Answer · edited Dec 09 '15 at 00:39

In my opinion, if you are going to use linq then embrace it, get rid of that esoteric notation :)

   public IEnumerable<TimelineItem> GetTimeLineItems(int SelectedPID)
   {
      return db.TimelineItems.Where(tl => tl.ProductID == SelectedPID)
        .Select( tl => new TimelineItem {
            Description = tl.Description,
            Title = tl.Title })
        .AsEnumerable<TimelineItem>();
   }

score 7 · Answer 2 · edited Apr 26 '15 at 04:21

7

The reason you are getting null is because you are trying to convert an IQueryable based on an an anonymous type to IEnumerable<TimelineItem> (new { t.Description, t.Title } creates an instance of an anonymous type with two fields - Description and Title) You should remove the Select part to make it work.

If you would like to select only Description and Title, create a named type with these two fields, and return an IEnumerable of that type:

public class TitleDescr {
    public string Title {get;set;}
    public string Description {get;set;}
}

public IEnumerable<TitleDescr> GetTimeLineItems(int SelectedPID)
{
    return from t in db.TimelineItems
                     where t.ProductID == SelectedPID
                     select new TitleDescr { t.Description, t.Title };
}

edited Apr 26 '15 at 04:21

Nikola Bogdanović

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answered Apr 11 '12 at 01:10

Sergey Kalinichenko

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I don't want to select all items.I want to select only description and title ,that's why I am using Select – Renny Apr 11 '12 at 01:12
@sureshcd10cvvc Please see my edit for an explanation of what to do if you need a projection of your result. – Sergey Kalinichenko Apr 11 '12 at 01:17

score -1 · Answer 3 · answered Oct 02 '15 at 05:16

Use auto mapper to convert IQueryable to IEnumerable

 StudentsModel IEmodel = new StudentsModel();//IEnumerable 
            try {
                var Queryablemodel = _tblStudents.GetQueryable().FirstOrDefault(x => x.CNIC == strCNIC && x.LoginPassword == strPassword);//IQueryable
               //conversion with Auto Mapper
                IEmodel = AutoMapper.Mapper.Map(Queryablemodel , IEmodel ); 
            }
            catch(Exception ex){
                throw ex;
            }

Converting iQueryable to IEnumerable

3 Answers3

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