Order by field which is made of 3 sub strings in LINQ

Question

I have a LINQ query as below,

 var sortedResults = (from r in this.CurrentTemplateInfos
                      where r.EffectiveEnd == null
                      orderby r.Description
                      select r);

From the above query ,field Description is made of 3 sub strings(Showtype:Show:StartDate-Endate) separated by Colon (:). Now as per the new requirement i need to do orderby ascending for first two fields(Showtype:Show) and descending by StartDate from the description value, e.g.

Show : Main Street Trolley : 6/12/2010 - 7/15/2010

ShowType : Parades : 2/10/2010 - 6/16/2010

ShowType : Parades : 6/17/2010 - 8/26/2010

ShowType : Parades : 8/27/2010 - 10/26/2010

Output should be

Show : Main Street Trolley : 6/12/2010 - 7/15/2010

ShowType :Parades : 8/27/2010 - 10/26/2010

ShowType : Parades : 6/17/2010 - 8/26/2010

ShowType : Parades : 2/10/2010 - 6/16/2010

please help me on this.

you need to implement Icomparer. Here is an example http://stackoverflow.com/a/985685/1305119 — Suresh Kumar Veluswamy, Jun 10 '15 at 07:32
Why do you store multiple informations in one property? Separate them from each other. Add other properties for `StartDate`, `EndDate`(`DateTime`), `ShowType`, `Show`(`String`). — Tim Schmelter, Jun 10 '15 at 07:35

Richard · Answer 1 · 2015-06-10T15:03:08.090

Break the field up into separate fields with a helper type, and then use that in order by clauses. Something like:

// Elsewhere
class SortFields {
  public string Field1 { get; set; }
  public string Field2 { get; set; }
  public DateTime StartDate { get; set; }

  public static SortFields SplitInput(string input) {
    // Factory... Implement split/parse logic
  }
}

and then

from r in this.CurrentTemplateInfos
where r.EffectiveEnd == null
let fields = SortField.SplitInput(r.Description)
// This means sort by Field1, then Field2 and then StartDate
// and the default in each criterion is ascending unless you
// specify descending keyword.
orderby fields.Field1, fields.Field2, fields.StartDate descending 
select r

Note, one could use use multiple let clauses to do the split/parse, but I think the little helper type is clearer.

Good idea. But i think the best approach would be to store those informations in separate properties in the first place. — Tim Schmelter, Jun 10 '15 at 07:37
@TimSchmelter I agree. Equally implementing `IComparable` on the type would be good. — Richard, Jun 10 '15 at 07:41

Eren Ersönmez · Answer 2 · 2015-06-10T07:56:03.367

1

var sortedResults = from r in this.CurrentTemplateInfos
                    where r.EffectiveEnd == null
                    let parts = r.Description.Split(':')
                    let firstPart = parts[0] + parts[1]
                    let startDate = DateTime.Parse(parts[2].Split('-').First().Trim())
                    orderby firstPart, startDate descending
                    select r;

edited Jun 10 '15 at 07:56

answered Jun 10 '15 at 07:41

Eren Ersönmez

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I was writing almost the same answer, but I would put the `where` right after `from`. – Dennis_E Jun 10 '15 at 07:44
@Dennis_E I agree, changed. – Eren Ersönmez Jun 10 '15 at 07:56
@ Eren Ersönmez : Thanks for your inputs. It really great and worked as expected. Thanks much. – anitha lm Jun 10 '15 at 09:31

Order by field which is made of 3 sub strings in LINQ

2 Answers2