WPF Binding to local variable

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

No it has to be a visible property.

Answer 2

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.

Answer 3

To bind to a local "variable" the variable should be:

1. A property, not a field.
2. Public.
3. Either a notifying property (suitable for model classes) or a dependency property (sutable for view classes)

Examples:

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 PropertyChangedEventHandler PropertyChanged;
}

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 ...
}

Answer 4

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

{Binding Text}