Data bind to a portion of a collection

observablecollection
wpf observablecollection binding
bind to a collection and display information based on selection
listview observablecollection
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observablecollection in wpf mvvm
itemssource=(binding observablecollection)
wpf datagrid binding observablecollection example

I have a static collection of items (say numbers from 1 to 100) that I'm presenting in a ComboBox. I can bind these items to the ComboBox no problem.

My question is how to bind a second ComboBox to a subset of those items. The behavior I want is to have the second ComboBox bound to the subset of items remaining after the first ComboBox is selected. For example the first ComboBox would show 1,2,3...,100. If the number 43 is selected in the first ComboBox then the second ComboBox should show 44,45,...,100.

How can this be accomplished and have the second ComboBox update if the first is changed without a lot of code-behind?


How to: Create and Bind to an ObservableCollection, Find out how to create and bind to a collection that derives from the see the Binding to Collections section in the Data Binding Overview. The ListBox and the ContentControl bind to the same source. The Path properties of both bindings are not specified because both controls are binding to the entire collection object. You must set the IsSynchronizedWithCurrentItem property to true for this to work.


I'd go with MVVM design but if you want to just do testing and want to see quick results without going into design patterns then I'd suggest using something like CLINQ / BLINQ / Obtics framework to leverege the power of LINQ while keeping the results live for the combo box.

Since LoSciamano has already posted a reply on that (while i was posting this!) I won't dive into details of MVVM implementation

WPF Data Binding - Collection Views, The one hundred and fourth part of the Windows Presentation Foundation Fundamentals tutorial continues to look at data binding for multiple� <CollectionContainer Collection="{Binding GreekGods, Source={StaticResource CompositeCollectionVM}}"/> Note that when using x:Reference the compiler easily trips you up with cyclical dependency errors, to avoid those place your CompositeCollection in the resources of the control you reference, then insert it wherever it belongs using the


I would expose the first collection as an ObservableCollection<T> and the second collection as a bare IEnumerable. You can then use the default collection view to handle the events necessary to re-filter the sub collection.

class FilteredVM : ViewModelBase
{
    public ObservableCollection<MyVM> Items { get; private set; }
    public IEnumerable<MyVM> SubItems { get; private set; }

    public FilteredVM()
    {
        this.Items = new ObservableCollection<MyVM>();
        this.SubItems = Enumerable.Empty<MyVM>();

        var view = CollectionViewSource.GetDefaultView(this.Items);
        view.CurrentChanged += (sender, e) => { SetupFilter();  };
        view.CollectionChanged += (sender, e) => { SetupFilter(); };
    }

    private void SetupFilter()
    {
        var view = CollectionViewSource.GetDefaultView(this.Items);
        var current = view.CurrentItem;
        if (current != null)
        {
            this.SubItems = this.Items.Where((vm,idx) => idx > view.CurrentPosition);
        }
        else
        {
            this.SubItems = Enumerable.Empty<MyVM>();
        }

        this.OnPropertyChanged("SubItems");
    }
}

Alternatively, if you'd like to keep CollectionViewSource out of your VM:

class FilteredVM : ViewModelBase
{
    private MyVM selectedItem;
    public MyVM SelectedItem
    {
        get { return this.selectedItem; }
        set
        {
            if (value != this.selectedItem)
            {
                this.selectedItem = value;
                this.OnPropertyChanged("SelectedItem");
                this.SetupFilter();
            }
        }
    }

    public ObservableCollection<MyVM> Items { get; private set; }
    public IEnumerable<MyVM> SubItems { get; private set; }

    public FilteredVM()
    {
        this.Items = new ObservableCollection<MyVM>();
        this.SubItems = Enumerable.Empty<MyVM>();

        this.Items.CollectionChanged += (sender, e) => { this.SetupFilter(); };
    }

    private void SetupFilter()
    {
        if (this.SelectedItem != null)
        {
            var item = this.SelectedItem; // save for closure
            this.SubItems = this.Items.SkipWhile(vm => vm != item).Skip(1);
        }
        else
        {
            this.SubItems = Enumerable.Empty<MyVM>();
        }

        this.OnPropertyChanged("SubItems");
    }
}

Keep in mind this will require SelectedItem to be properly bound in the View to the ViewModel. The first approach listed allows the SelectedItem to be bound to anywhere (or nowhere).

The "foreach" binding, The foreach binding duplicates a section of markup for each entry in an array, and To turn it on for a specific binding, set the noChildContext option to true . I have a custom collection that I am passing to a WPF client, which is binding the collection to a datagrid using AutoGenerateColumns="True".The datagrid, however, is displaying empty rows (albeit the right number of empty rows).


Have 2 Observable collections so that when item in the 1st box is selected, it will kick off method which clears and re populates the 2nd collection. As it is observableCollection, it gets reflected in the WPF GUI automatically

Observable Collections, Data Binding, And Complex Automation In , The other portion needed for this mechanism is the Enumeration Binding which assigns the correct units when the system of measurement� How to: Implement a CompositeCollection. 03/30/2017; 2 minutes to read +7; In this article Example. The following example shows how to display multiple collections and items as one list using the CompositeCollection class.


Here is a concrete example (as usual, may be improved, but the idea is here) :

Code behind an view model :

public partial class Window1 : Window
{
    public Window1()
    {
        InitializeComponent();
        DataContext = new ViewModel();
    }
}


public class ViewModel : INotifyPropertyChanged
{
    public ViewModel()
    {
        Initialsource = new ObservableCollection<int>();
        for (int i = 0; i < 101; i++)
        {
            Initialsource.Add(i);
        }
    }

    private int _selectedsourceItem;
    public int SelectedsourceItem
    {
        get { return _selectedsourceItem; }
        set
        {
            _selectedsourceItem = value;
            SubsetSource = new ObservableCollection<int>(Initialsource.Where(p => p > _selectedsourceItem));
            InvokePropertyChanged(new PropertyChangedEventArgs("SubsetSource"));
            InvokePropertyChanged(new PropertyChangedEventArgs("SelectedsourceItem"));
        }
    }

    private ObservableCollection<int> _initialsource;
    public ObservableCollection<int> Initialsource
    {
        get { return _initialsource; }
        set
        {
            _initialsource = value;
            InvokePropertyChanged(new PropertyChangedEventArgs("Initialsource"));
        }
    }

    private ObservableCollection<int> _subsetSource;
    public ObservableCollection<int> SubsetSource
    {
        get { return _subsetSource ?? (_subsetSource = new ObservableCollection<int>()); }
        set
        {
            _subsetSource = value;
            InvokePropertyChanged(new PropertyChangedEventArgs("SubsetSource"));
        }
    }

    public event PropertyChangedEventHandler PropertyChanged;

    public void InvokePropertyChanged(PropertyChangedEventArgs e)
    {

        PropertyChangedEventHandler handler = PropertyChanged;
        if (handler != null) handler(this, e);
    }
}

XAML :

<Grid HorizontalAlignment="Center" VerticalAlignment="Center">
    <StackPanel Orientation="Horizontal">
        <ComboBox Width="100" ItemsSource="{Binding Initialsource}" SelectedItem="{Binding SelectedsourceItem, Mode=TwoWay}"></ComboBox>
        <ComboBox Width="100" ItemsSource="{Binding SubsetSource}"></ComboBox>
    </StackPanel>
</Grid>

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Part 18, In the previous lessons we learned about the Data Model and how it is used as We learned about the binding syntax used by XAML to bind to the Data If an instance of an object that is part of a collection managed by the� That much I figured out. I'm looking at it from binding the ItemsSource property of the datagrid, where the collection I'm binding to is a collection of objects with properties that reference other objects, i.e. a keyvaluepair or another class. I'm looking into itemtemplating, however I'm trying to keep things generic and dynamic.


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