WP7 Insert all linq results in an ObservableCollection

Question

I parse an xml results from a webservice using linq :

XElement items = XElement.Parse(e.Result);
MyListBox.ItemsSource = from item in items.Descendants("node")
            select new MyViewModel
            {
               ...
            };

This automatically populate my ListBox. But the problem is, I usually access my ObservableCollection like this :

App.MyViewModel.MyItems;

having in my xaml :

ItemsSource="{Binding MyItems,}"

How can I modify directly my ObservableCollection ? I read Cast LINQ result to ObservableCollection and tried this :

var v = from item in items.Descendants("node")
            select new MyViewModel
            {
               ...
            };
OApp.MyViewModel.MyItems = new ObservableCollection<MyViewModel>(v);

But I can't since this in WP7 (Silverlight 3), and there is no constructor like this

Thanks !

Note (in case you didn't know): if you are just displaying the items (without adding/removing) then you don't need to use an ObservableCollection. An IEnumerable will work fine. — Francesco De Vittori, Nov 24 '10 at 22:23

score 1 · Accepted Answer · answered Nov 24 '10 at 21:24

I'd just invent a static method like this:-

public static ObservableCollection<T> CreateObservableCollect<T>(IEnumerable<T> range)
{
    var result = new ObservableCollection<T>();
    foreach (T item in range)
    {
        result.Add(item);
    }
    return result;
}

Now your last line of code becomes:-

 OApp.MyViewModel.MyItems = new CreateObservableCollection<MyViewModel>(v);

score 0 · Answer 2 · answered Nov 24 '10 at 17:16

0

The constructor you're trying to use is in Silverlight, just not available on the phone. (as per MSDN)

Unfortunately, you'll have to populate your ObservableCollection yourself.

answered Nov 24 '10 at 17:16

Matt Lacey

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score 0 · Answer 3 · answered Nov 24 '10 at 17:17

Do you need ObservableCollection? Do you need add or delete objects from collection or just update?

If only update, you can change MyViewModel.MyItems to:

public MyTypeOfCollection MyItems
{
    get { return _myItems; }
    set
    {
        _myItems = value;
        OnNotifyPropertyChanged("MyItems");//invoke INotifyPropertyChanged.PropertyChanged
    }
}

If you need adding or deleting of items, you can extend your collection to:

public static class Extend
{
    // Extend ObservableCollection<T> Class
    public static void AddRange(this System.Collections.ObjectModel.ObservableCollection o, T[] items)
    {
        foreach (var item in items)
        {
            o.Add(item);
        }
    }
}

WP7 Insert all linq results in an ObservableCollection

3 Answers3