I'm pretty new to WPF and XAML and now I'm stuck with data binding for days! I just wanted to bind some nested properties to a TextBox and ListView (via XAML), but I'm doing it wrong. Here's my Sample Code:
MainWindow.xaml.cs
namespace CounterTestNestedDataBinding
{
public partial class MainWindow : Window
{
public MyModel MyModel { get; set; }
public MainWindow()
{
InitializeComponent();
MyModel = new MyModel { MyCounter = new Counter() };
}
private void Button_Click(object sender, RoutedEventArgs e)
{
MyModel.MyCounter.incrementCounter();
}
}
}
MyModel.cs
namespace CounterTestNestedDataBinding
{
public class MyModel : INotifyPropertyChanged
{
public Counter _myCounter;
public Counter MyCounter
{
get { return _myCounter; }
set
{
_myCounter = value;
NotifyPropertyChanged("MyCounter");
}
}
// some other members and properties ...
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(string property)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(property));
}
}
}
}
Counter.cs
namespace CounterTestNestedDataBinding
{
public class Counter : INotifyPropertyChanged
{
#region Members
private int _currentNumber;
private ObservableCollection<int> _historyList;
#endregion
#region Constructor
public Counter()
{
_currentNumber = 0;
_historyList = new ObservableCollection<int>();
}
#endregion
#region Properties
public int CurrentNumber
{
get { return _currentNumber; }
set
{
_currentNumber = value;
NotifyPropertyChanged("CurrentNumber");
}
}
public ObservableCollection<int> HistoryList
{
get { return _historyList; }
set
{
_historyList = value;
NotifyPropertyChanged("HistoryList");
}
}
#endregion
public void incrementCounter()
{
HistoryList.Add(CurrentNumber);
CurrentNumber++;
}
public override string ToString()
{
return string.Format("CurrentNumber: {0}, HistoryList: {1}", _currentNumber, String.Join(",", _historyList));
}
public event PropertyChangedEventHandler PropertyChanged;
private void NotifyPropertyChanged(string property)
{
if (PropertyChanged != null)
{
PropertyChanged(this, new PropertyChangedEventArgs(property));
}
}
}
}
MainWindow.xaml
<Window x:Class="CounterTestNestedDataBinding.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:counterTestNestedDataBinding="clr-namespace:CounterTestNestedDataBinding"
Title="MainWindow" Height="350" Width="200" ResizeMode="NoResize" WindowStartupLocation="CenterScreen"
DataContext="{Binding RelativeSource={RelativeSource Self}}"
>
<StackPanel Orientation="Vertical">
<TextBox x:Name="TextBoxCounterCurrent" Text="{Binding MyModel.MyCounter.CurrentNumber}"/>
<Button Content="Button" Click="Button_Click"/>
<ListView x:Name="ListViewCounterHistory" Height="75" ItemsSource="{Binding MyModel.MyCounter.HistoryList}"></ListView>
</StackPanel>
</Window>
My questions:
How can I bind nested properties? Is it possible? Why does something like
Text="{Binding MyModel.MyCounter.CurrentNumber}"
not work?
Is the "DataContext" set correct in the XAML?
Set your data context in the constructor like this:
public MainWindow()
{
InitializeComponent();
MyModel = new MyModel { MyCounter = new Counter() };
this.DataContext = MyModel;
}
and then of course the path to your data changes because the data that you are binding is under MyModel. Your bindings should be changed as follows:
<StackPanel Orientation="Vertical">
<TextBox x:Name="TextBoxCounterCurrent" Text="{Binding MyCounter.CurrentNumber}"/>
<Button Content="Button" Click="Button_Click"/>
<ListView x:Name="ListViewCounterHistory" Height="75" ItemsSource="{Binding MyCounter.HistoryList}"></ListView>
</StackPanel>
EDIT:
This is how you do it by using XAML.
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:WpfApplication1"
xmlns:system="clr-namespace:System;assembly=mscorlib"
Title="MainWindow" Height="350" Width="525" >
<Window.Resources>
<local:MyModel x:Key="myModal" />
</Window.Resources>
<StackPanel Orientation="Vertical" DataContext="{StaticResource myModal}">
<TextBox x:Name="TextBoxCounterCurrent" Text="{Binding MyCounter.CurrentNumber}"/>
<Button Content="Button" Click="Button_Click"/>
<ListView x:Name="ListViewCounterHistory" Height="75" ItemsSource="{Binding MyCounter.HistoryList}"></ListView>
</StackPanel>
and code changes like this:
public partial class MainWindow : Window
{
public MyModel MyModel { get; set; }
public MainWindow()
{
InitializeComponent();
//MyModel = new MyModel { MyCounter = new Counter() };
//this.DataContext = MyModel;
}
private void Button_Click(object sender, RoutedEventArgs e)
{
var myModel = this.Resources["myModal"] as MyModel;
if (myModel != null)
{
myModel.MyCounter.incrementCounter();
}
}
}
By the way you should initialize _myCounter
in MyModel constructor.
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