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POCombobox SelectedItem doesn't update when source changes
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  1. POCombobox SelectedItem doesn't update when source changes
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    copied!<p>I have a viewmodel which implement <code>INotifyPropertyChanged</code>. On this viewModel is a property called <code>SubGroupingView</code>. This property is bound to the selected item of a combo box. When i change the combo box, the source property is being updated fine, but when I change the source property or when the control is initialized, the <code>combobox.selectedItem</code> is NOT reflecting what exists in the property.<br> Here is some code to get you started: </p> <pre><code>&lt;ComboBox Grid.Column="3" Grid.Row="1" Margin="0,1,4,1" SelectedItem="{Binding Path=SubGroupingView, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay, diag:PresentationTraceSources.TraceLevel=High}" ItemsSource="{Binding Columns}" DisplayMemberPath="DisplayName"&gt; </code></pre> <p>The property raises the <code>PropertyChanged</code> event and the TraceSource output shows me that the binding detected it and transferred the value, its just that the combobox isn't reflecting it. Any ideas would be most welcome!</p> <p>EDIT:<br> output from the trace source is this: </p> <pre><code>System.Windows.Data Warning: 91 : BindingExpression (hash=23631369): Got PropertyChanged event from ReportViewModel (hash=52844413) System.Windows.Data Warning: 97 : BindingExpression (hash=23631369): GetValue at level 0 from ReportViewModel (hash=52844413) using RuntimePropertyInfo(SubGroupingView): DataColumnViewModel (hash=58231222) System.Windows.Data Warning: 76 : BindingExpression (hash=23631369): TransferValue - got raw value DataColumnViewModel (hash=58231222) System.Windows.Data Warning: 80 : BindingExpression (hash=23631369): TransferValue - implicit converter produced DataColumnViewModel (hash=58231222) System.Windows.Data Warning: 85 : BindingExpression (hash=23631369): TransferValue - using final value DataColumnViewModel (hash=58231222) </code></pre> <p>Here is the code for the source property:</p> <pre><code>public class ReportViewModel : ViewModelBase, IReportTemplate { public DataColumnViewModel SubGroupingView { get { return GetViewModel(_report.SubGrouping); } set { if (_report.SubGrouping == value.ColumnName) return; _report.SubGrouping = value.ColumnName; RefreshDataSeries(); base.OnPropertyChanged("SubGroupingView"); base.OnPropertyChanged("IsReady"); } } } </code></pre> <p>Note: <code>ViewModelBase</code> implements <code>INotifyPropertyChange</code>.</p> <p><strong>ANSWER</strong><br> I overloaded the ==, != operators, <code>GetHashCode()</code>, and <code>Equals(object)</code> and now it is working nicely. Thanks for all of your help!</p>
 

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