Sorting a nested list array in C#

Question

I am trying to sort a nested array of elements in asp.net and having a bit of trouble. Currently I have a playlist which has a model as so:

public class Playlist
{
    public Playlist()
    {
        this.date = new List<dates>();
    }
    [Key]
    public int id { get; set; }
    public string UserId { get; set; }
    public List<dates> date { get; set; }

    public class dates
    {
        [Key]
        public int dates_id { get; set; }
        public List<places> place {get; set;}
    }

    public class places
    {
        [Key]
        public int places_id { get; set; }
        public string id { get; set; }
    }
}`

As you can see it is a nested array of objects, dates, with another array of objects, places.

What I am doing now is pulling out the data as so:

playlist = db.Playlists.Where(e => e.UserId.Equals(userId)).OrderBy(q => q.id).Include("date.place").ToList();

What I realized was that the places in the date object wasn't being pulled out in a sorted array based on the place_Id, but rather randomly. Is there a way that I could pull out the playlist with the places ordered? The .OrderBy(q => q.id) would only pull an ordered list for the playlist and not the nested objects.

so you need a list ordered by two fields (places.places_id , playlist.id) in that order? — alexm
– alexm, Commented Feb 7, 2016 at 22:38

alexm · Accepted Answer · 2016-02-07 23:07:35Z

2

You can arrange the order of items in nested lists on the client:

// Fetch playlists given a user id
var playlist = db.Playlists
      .Where(e => e.UserId.Equals(userId))
      .OrderBy(q => q.id)
      .Include("date.place")
      .ToList();

// Order places and dates by their id's
foreach(var item in playlist)
{
   foreach(var d in item.dates)
   {
        d.places.Sort((left, right) => 
         left.id.CompareTo(right.id));
   }

   item.dates.Sort((left, right)=>
      left.id.CompareTo(right.id));
}

edited Feb 7, 2016 at 23:07

answered Feb 7, 2016 at 22:55

alexm

6,89022 silver badges24 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Julius Doan Over a year ago

Great that worked perfectly. I was actually expecting there to be a something that could be done in a single line without the nested for loops, but this looks great!

Avin Zarlez · Accepted Answer · 2016-02-07 22:16:15Z

0

First, you should sort each objects places lists, then sort the main/date list.

Attempting to sort both at once might cause random results

answered Feb 7, 2016 at 22:16

Avin Zarlez

1,6821 gold badge12 silver badges13 bronze badges

1 Comment

Julius Doan Over a year ago

I guess that is my question. how would I sort the places lists? Would I be building the list first then resaving into the playlist? Some code may be helpful, Thanks

Collectives™ on Stack Overflow

Sorting a nested list array in C#

2 Answers 2

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related