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POupdate itemsource in codebehind not changing with xaml binding
 

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  1. POupdate itemsource in codebehind not changing with xaml binding
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    <p>The problem is that I’m changing the collection of items at runtime and I can’t get the combobox to update to show the new items. I’d like to achieve this via xaml.</p> <p>I’d like to solve this for a single combobox, and then also for a datagrid either as either a datagridComboBoxColumn or as a templatecolumn containing a combobox as the datatemplate. </p> <p>I’ve got code like:</p> <pre><code>public class Member { public string PublicID {get; set;} public string Description {get; set;} } public ObservableCollection&lt;Member&gt; ComboBoxSource; public UpdateComboBoxContents() { List&lt;Member&gt; newList; // Omitted Code to retrieve list from datasource.. ComboBoxSource = new ObservableCollection&lt;Member&gt;(newList); // If I uncomment the next line, combobox will show new contents: //myComboBox.itemssource = ComboBoxSource; // I’ve also tried.. OnPropertyChanged("ComboBoxListSource"); } public event PropertyChangedEventHandler PropertyChanged; private void OnPropertyChanged(string Name) { PropertyChangedEventHandler handler = PropertyChanged; if (handler != null) { handler(this, new PropertyChangedEventArgs(Name)); } } </code></pre> <p>Where:</p> <pre><code>public partial class MyForm: UserControl, INotifyPropertyChanged </code></pre> <p>Combobox xaml looks like:</p> <pre><code>&lt;ComboBox Name="myComboBox" SelectedValuePath="PublicID" DisplayMemberPath="Description" ItemsSource="{Binding ComboBoxListSource, UpdateSourceTrigger=PropertyChanged}"/&gt; </code></pre> <p>I figure I’m screwing up binding or implementing INotifyPropertyChanged. In debug I noticed that the handler is always null so the event isn’t raised.</p> <p>For the second part of this question (implementing into a datagrid) I’ve got:</p> <pre><code>public observableCollection&lt;DatarowWithMember&gt; ListDataRowWithMember; // Code to populate list.. myDataGrid.Itemsource = ListDataRowWithMember </code></pre> <p>where DataRowWithMember is a class that implements INotifyPropertyChanged and has a MemberID property which should point to Member’s PublicID</p> <p>I’ve tried this xaml:</p> <pre><code>&lt;DataGridTemplateColumn Header="Group" Width="*"&gt; &lt;DataGridTemplateColumn.CellTemplate&gt; &lt;DataTemplate&gt; &lt;ComboBox ItemsSource="{Binding ComboBoxListSource, RelativeSource={RelativeSource AncestorType=UserControl}}" SelectedValue="{Binding MemberID, UpdateSourceTrigger=PropertyChanged}" DisplayMemberPath="Description" SelectedValuePath="PublicID" IsHitTestVisible="False" SelectionChanged="ComboBoxChanged"&gt; &lt;/ComboBox&gt; &lt;/DataTemplate&gt; &lt;/DataGridTemplateColumn.CellTemplate&gt; &lt;DataGridTemplateColumn.CellEditingTemplate&gt; &lt;DataTemplate&gt; &lt;ComboBox ItemsSource="{Binding ComboBoxListSource, RelativeSource={RelativeSource AncestorType=UserControl}}" DisplayMemberPath="Description" SelectedValuePath="PublicID" SelectedValue="{Binding MemberID, UpdateSourceTrigger=PropertyChanged}" SelectionChanged="ComboBoxChanged"/&gt; &lt;/DataTemplate&gt; &lt;/DataGridTemplateColumn.CellEditingTemplate&gt; &lt;/DataGridTemplateColumn&gt; </code></pre> <p>Solution: As others pointed out, I had a typo with ComboBoxSource and ComboBoxListSource - this wasn't a problem in code but my error in writing out this question.</p> <p>Checking output window did indeed show binding problems namely that property ComboBoxSource could not be found. I changed to:</p> <pre><code>private ObservableCollection&lt;Member&gt; _ComboBoxSource = new ObservableCollection&lt;Member&gt;() public ObservableCollection&lt;Member&gt; ComboBoxSource { get { return _ComboBoxSource; } } </code></pre> <p>and that worked. class Properties vs members ?</p>
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    1. USandrew
    1. USandrew
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    1. COhow are you setting DataContext of your usercontrol.? Handler is null if the class implementing INotifyPropertyChanged is not set as DataContext or bound to the view
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      1. POupdate itemsource in codebehind not changing with xaml binding
      1. USNitin
    2. CODo you get Binding expression errors during debug inside your output window?
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      1. POupdate itemsource in codebehind not changing with xaml binding
      1. USJordy van Eijk
    3. COIn my control's initialise i've got DataContext = this;
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      1. USandrew
 

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