Wpf: binding data from an object

Question

Wpf: binding data from an object

There is a separate class Piple with a bunch of data about a person, I create an object of this class in MainWinow. In the main window of the application, I have a lot of different texboxes for this object (first name, last name, etc.). Is it possible to somehow use Binding, to make it so that when changing the object, the data in the corresponding textbox, would change and vice versa, when changing in textbox, the corresponding fields in Piple would change?

Here is the class code Piple:

namespace WpfApplication4
{
    public class Piple 
     {          
        public string name;
        public string name2;
        public Piple()
        {   
            name="Иван";
            name2="Иванов";
        }    
    }
}

Main class code C#:

  namespace WpfApplication4
  {
        /// <summary>
        /// Логика взаимодействия для MainWindow.xaml
        /// </summary>
        public partial class MainWindow : Window
        {
            Piple chel = new Piple();
            public MainWindow()
            {
                InitializeComponent();
                this.DataContext = this;                    
            }
         }
}

Window code in XAML

<Window x:Class="WpfApplication4.MainWindow"

        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525"  WindowState="Maximized">
    <Grid >

        <TextBox HorizontalAlignment="Left" Height="23" TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="120" Margin="28,76,0,0" RenderTransformOrigin="0.5,0.5"/>


        <TextBox HorizontalAlignment="Left" Height="23"  TextWrapping="Wrap" Text="" VerticalAlignment="Top" Width="120" Margin="28,135,0,0"/>

    </Grid>
</Window>

You need to bind the data from chel.name and chel.name2 to the corresponding textbox, respectively. Can you tell me if this can be done with Binding?

4

c#wpf .net framework binding

Author: RussCoder, 2013-11-06

Source

1 answers

score 7 · Answer 1

Binding to class fields in WPF is not possible, you need at least properties (property).
In order for the new values to be displayed in the control when the class properties are changed, the class must inherit from the INotifyPropertyChanged interface
You yourself did not register bindings for textboxes.

It should all look something like this:

    public class People : INotifyPropertyChanged // Наследуемся от нужного интерфеса
    {
        // Ваши поля 
        private string name, name2;

        public event PropertyChangedEventHandler PropertyChanged; // Событие, которое нужно вызывать при изменении

        // Для удобства обернем событие в метод с единственным параметром - имя изменяемого свойства
        public void RaisePropertyChanged(string propertyName)
        {
            // Если кто-то на него подписан, то вызывем его
            if (PropertyChanged != null)
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
        }

        // А тут будут свойства, в которые мы обернем поля
        public string Name
        {
            get { return name; }
            set
            {
                // Устанавливаем новое значение
                name = value;
                // Сообщаем всем, кто подписан на событие PropertyChanged, что поле изменилось Name
                RaisePropertyChanged("Name");
            }
        }

        public string Name2
        {
            get { return name2; }
            set
            {
                // Устанавливаем новое значение
                name2 = value;
                // Сообщаем всем, кто подписан на событие PropertyChanged, что поле изменилось Name2
                RaisePropertyChanged("Name2");
            }
        }
    }

In the control code, we create an instance of the class and write the DataContext (in fact, the DataContext can be written in marking up the control):

        public MainWindow()
        {
            // Создаем экземпляр нашего класса
            P = new People(){Name = "Ololosha", Name2 = "Trololosha"};
            InitializeComponent();
            // Устанавливаем как контекст данных
            DataContext = P;
        }

And in the markup of the control, we write textboxes:

<TextBox Text="{Binding Path=Name}"/>
<TextBox Text="{Binding Path=Name2}"/>

Now it will work the way you want it to.

Perhaps we should also mention such a binding property as UpdateSourceTrigger. It describes when to change the source. By default, the textbox has the value LostFocus, i.e. the change will occur only when the TextBox loses focus. If you want the changes to happen immediately, then you need to UpdateSourceTrigger set to PropertyChanged:

<TextBox Text="{Binding Path=Name2, UpdateSourceTrigger=PropertyChanged}"/>

I would I advised you to find a good book on WPF. Here there is a pretty good site about WPF (and not only about it), at least it helped me a lot at the time