WPF Binding to local variable - wpf

Question

Can you bind to a local variable like this?
SystemDataBase.cs
namespace WebWalker
{
public partial class SystemDataBase : Window
{
private string text = "testing";
...
SystemDataBase.xaml
<TextBox
Name="stbSQLConnectionString"
Text="{SystemDataBase.text}">
</TextBox>
??
Text is set to the local variable "text"

Answer 1

The pattern is:
public string Text {get;set;}
and the binding is
{Binding Text, RelativeSource={RelativeSource FindAncestor, AncestorType=Window}}
If you want the binding to update automatically you should make it a DependencyProperty.
I think 3.5 added ElementName to bindings, so the following is a little easier:
<Window x:Name="Derp" ...
<TextBlock Text="{Binding Text, ElementName=Derp}"/>

Answer 2

To bind to a local "variable" the variable should be:
A property, not a field.
Public.
Either a notifying property (suitable for model classes) or a dependency property (sutable for view classes)
Notifying property example:
public MyClass : INotifyPropertyChanged
{
private void PropertyType myField;
public PropertyType MyProperty
{
get
{
return this.myField;
}
set
{
if (value != this.myField)
{
this.myField = value;
NotifyPropertyChanged("MyProperty");
}
}
}
protected void NotifyPropertyChanged(String propertyName)
{
if (PropertyChanged != null)
PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
}
public event PropertyChangedEventHandler PropertyChanged;
}
Dependency property example:
public MyClass : DependencyObject
{
public PropertyType MyProperty
{
get
{
return (PropertyType)GetValue("MyProperty");
}
set
{
SetValue("MyProperty", value);
}
}
// Look up DependencyProperty in MSDN for details
public static DependencyProperty MyPropertyProperty = DependencyProperty.Register( ... );
}

Answer 3

If you're doing a lot of this, you could consider binding the DataContext of the whole window to your class. This will be inherited by default, but can still be overridden as usual
<Window DataContext="{Binding RelativeSource={RelativeSource Self}}">
Then for an individual components you can use
Text="{Binding Text}"

Answer 4

To bind a local variable which is present in your Window class it has to be :
1. Public property
2. A notifying property. For this your window class should implement INotifyPropertyChanged interface for this property.
Then in the constructor
public Assgn5()
{
InitializeComponent();
this.DataContext = this; // or **stbSQLConnectionString**.DataContext = this;
}
<TextBox
Name="stbSQLConnectionString"
Text="{Binding text}">
</TextBox>

Answer 5

Need to add the following line in the int constructor:
this.DataContext = this;
And use this in the XAML:
<TextBox Text = "{Binding SomeProperty}" />
Exmaple:
MainWindow.xaml.cs
public partial class MainWindow : Window
{
public string PersonName { get; set; }
public MainWindow()
{
InitializeComponent();
PersonName = "default";
this.DataContext = this;
}
void button1_Click(object sender, RoutedEventArgs args)
{
MessageBox.Show($"Hello {PersonName}");
}
}
MainWindow.xaml
<StackPanel>
<TextBox Name="textbox1"
Text="{Binding PersonName, Mode=TwoWay}"
/>
<Button Name="button1" Click="button1_Click" Content="Click Me" />
</StackPanel>