Group Listbox for Windows Phone 7?

Question

I\'m looking for a way to group items similar to the way the applications below have it for there grouping. Is it possible to create a group listbox using View Models? I plan on

Answer 1

Nothing prevents you from creating a custom ordered collection that suits that precise purpose. Here's the collection type I usually use for it, when integrating it with the LongListSelector in the Silverlight Toolkit

You'll obviously have to modify the GroupHeaderTemplate but that's very easy.

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;

namespace LongListSample
{
    public class LongListCollection : ObservableCollection>
        where T : IComparable
    {
        public LongListCollection()
        {
        }

        public LongListCollection(IEnumerable items, Func keySelector)            
        {
            if (items == null)
                throw new ArgumentException("items");

            var groups = new Dictionary>();

            foreach (var item in items.OrderBy(x => x))
            {
                var key = keySelector(item);

                if (groups.ContainsKey(key) == false)
                    groups.Add(key, new LongListItem(key));

                groups[key].Add(item);
            }

            foreach (var value in groups.Values)
                this.Add(value);
        }
    }

    public class LongListItem : ObservableCollection
    {
        public LongListItem()
        {
        }

        public LongListItem(TKey key)
        {
            this.Key = key;
        }

        public TKey Key
        {
            get;
            set;
        }

        public bool HasItems
        {
            get
            {
                return Count > 0;
            }
        }
    }
}

Example of use: