C#: Binding textbox to object attribute

Question

I am new to object binding and I don' succeed to make it work.

I have a xaml window with the following textbox:

<Grid x:Name="gr_main" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="180,65,0,0" DataContext="{Binding currentproj}">
<Grid.RowDefinitions>
    <RowDefinition Height="Auto" />
</Grid.RowDefinitions>
<Grid.ColumnDefinitions>
    <ColumnDefinition Width="Auto" />
</Grid.ColumnDefinitions>

<TextBox Grid.Row="0" Grid.Column="2" x:Name="txt_localdir"  Height="25" TextWrapping="Wrap" Width="247" IsEnabled="False" Text="{Binding Path=Localdir, UpdateSourceTrigger=PropertyChanged}"/>

In the cs code of the main window, I define an instance of my Project class, called currentproj, as follows:

public partial class MainWindow : Window{
Project currentproj;

public MainWindow()
{            
    currentproj = new Project();
    InitializeComponent();
}}

The project class (defined in a Project.cs file) is as follows:

public partial class Project : Component, INotifyPropertyChanged { public event PropertyChangedEventHandler PropertyChanged;

private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
{
    if (PropertyChanged != null)
    {
        PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
}

private string _localdir;
public string Localdir
{
    get { return _localdir; }
    set
    {
        if (value != _localdir)
        {
            _localdir = value;
            NotifyPropertyChanged("Localdir");
        }
    }
}

public Project()
{
    InitializeComponent();
}

public Project(IContainer container)
{
    container.Add(this);

    InitializeComponent();
}}

However, even if I am binding the textbox.text attribute to the Localdir path of the currentproj object, the textbox is never updated. I see the PropertyChanged event is alwais null when I set the value of Localdir, but I don't understand why.

Have you tried setting Mode=TwoWay within your Binding in XAML? — ataraxia
– ataraxia, Commented Jun 6, 2018 at 15:07

Matt Norrie · Accepted Answer · 2018-07-13 13:19:21Z

1

Data binding works on the DataContext. The Grid's DataContext is not set correctly, this should be removed.

so the Grid definition should be:

<Grid x:Name="gr_main" HorizontalAlignment="Left" VerticalAlignment="Top" Margin="180,65,0,0">

Setting the Window DataContext to currentProj is done by:

public partial class MainWindow : Window{
Project currentproj;

public MainWindow()
{            
    currentproj = new Project();
    DataContext = currentproj;
    InitializeComponent();
}}

edited Jul 13, 2018 at 13:19

answered Jun 6, 2018 at 15:17

Matt Norrie

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