Question

I have a XAML code as follows:

<UserControl x:Class="LabsterApp.TestExplorer.TestExplorer"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:TestExplorer="clr-namespace:LabsterApp.TestExplorer" MinHeight="300">
    <Grid>
        <StackPanel MinWidth="120">
            <TreeView/>
            <Grid Name="TestInfo">
                <Grid.RowDefinitions>
                    <RowDefinition/>
                    <RowDefinition/>
                    <RowDefinition/>
                </Grid.RowDefinitions>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto"/>
                    <ColumnDefinition/>
                </Grid.ColumnDefinitions>
                <TextBox Text="Name:" Grid.Row="0" Grid.Column="0"/>
                <TextBox Text="{Binding ElementName=CurrentTestInfo, Path=TestName}" Grid.Row="0" Grid.Column="1"/>
            </Grid>
        </StackPanel>
    </Grid>
</UserControl>

I set the whole control’s data context to be its viewmodel (in the code behind):

public TestExplorer()
        {
            viewModel = new TreeExplorerViewModel();
            DataContext = viewModel;
            InitializeComponent();
        }

The viewmodel has a CurrentTestInfo object which has a TestName property (all public). At some point, I update the CurrentTestInfo (creating a new object each time) but the text in the textbox is not updated. I’ve tried using:

<TextBox Text="{Binding Path=CurrentTestInfo.TestName}" Grid.Row="0" Grid.Column="1"/>  

instead and also tried a nested binding (textbox\text\binding tags).
The relevant viewmodel part:

public void TreeNodeSelected(object selectedNode)
{
    var node = (FolderTreeNode)selectedNode;
    if (!node.IsFolder)
    {
        HandleTest(node);
        return;
    }
    HandleFolderNode(node);
}

This is a test node so we go to HandleTest:

    // puts null/"" in all the fields:
    CurrentTestInfo.Clear();
    // locate the node in the currentData table
    DataRow currentRow = null;
    foreach (DataRow dataRow in currentData.Rows)
    {
        if (dataRow["TestID"].ToString().Equals(string.Empty)) continue;
        if (node.TestId == Guid.Parse(dataRow["TestID"].ToString()))
        {
            currentRow = dataRow;
            break;
         }
     }
     CurrentTestInfo.TestName = currentRow["TestName"].ToString();
     CurrentTestInfo.Owner = currentRow["TestOwner"].ToString();
     CurrentTestInfo.LastUpdated = DateTime.Parse(currentRow["TestDate"].ToString());

TestInfo class:

public class TestInfo : INotifyPropertyChanged
    {
        private string testName;
        public string TestName
        {
            get { return testName; }
            set
            {
                testName = value;
                OnPropertyChanged(new PropertyChangedEventArgs("TestName"));
            }
        }

        private DateTime? lastUpdated;
        public DateTime? LastUpdated
        {
            get { return lastUpdated; }
            set
            {
                lastUpdated = value;
                OnPropertyChanged(new PropertyChangedEventArgs("LastUpdated"));
            }
        }

        private string owner;
        public string Owner
        {
            get { return owner; }
            set 
            {
                owner = value;
                OnPropertyChanged(new PropertyChangedEventArgs("Owner"));
            }
        }

        public void Clear()
        {
            TestName = string.Empty;
            Owner = string.Empty;
            LastUpdated = null;
        }

        public event PropertyChangedEventHandler PropertyChanged;
        public void OnPropertyChanged(PropertyChangedEventArgs e)
        {
            if (PropertyChanged != null)
                PropertyChanged(this, e);
        }
    }

What am I doing wrong?

Thanks.

Answer 1

Does your view model and TestInfo type implement INotifyPropertyChanged? Are you invoking the PropertyChanged event when the CurrentTestInfo and TestName properties are set?