Wpf Two-way data binding doesn't work with static classes

Question

I'm very new to C# and XAML. I'm trying to do a WPF project where there will be a good amount of data binding. Right now, I am able to do one way data binding without any problems, the issue I am facing is when I try to do two-way data binding.

This is the beginning of my Xaml file where I try to bind a text box to a static property in a static class:

<Window x:Class="interactive_fountain.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:interactive_fountain"
        xmlns:include="clr-namespace:interactive_fountain.Include"
        mc:Ignorable="d"
        Title="MainWindow" Height="450" Width="800">
    <Grid>
        <TextBox x:Name="ip_textBox" HorizontalAlignment="Left" Height="27" Margin="250,242,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="110" Text="{Binding Source={x:Static include:Communication.ipAddressServer}, Path=include:Communication.ipAddressServer, UpdateSourceTrigger=PropertyChanged}"/>
        <Button Content="Button" HorizontalAlignment="Left" Margin="221,131,0,0" VerticalAlignment="Top" Height="47" Width="139" Click="Button_Click_1"/>

...

This is the beginning of the C# MainWindow Code:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Net;
using System.Net.Sockets;
using System.Diagnostics;
using interactive_fountain.Include;

namespace interactive_fountain
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {

        
        public MainWindow()
        {
            InitializeComponent();
        }

        private void Button_Click_1(object sender, RoutedEventArgs e)
        {
            Trace.WriteLine("ip: " + Communication.ipAddressServer);
        }
...

And this is the beginning of the class I want to do data binding with:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Net;
using System.Net.Sockets;
using System.Diagnostics;

namespace interactive_fountain.Include
{
    public static class Communication
    {
        public static string ipAddressServer = "hello";
...

Whenever I try to do two-way data binding, the place holder "hello" doesn't appear anymore. When I write in the textBox and press the button, the output will always be ip: hello no matter what I write in the box. I have looked at a lot of threads regarding this issue but I did not find a solution that worked for me.
Does anyone know how I could make it work?
Thanks in advance!!

score 0 · Accepted Answer · edited Jul 02 '22 at 06:09

WPF data binding works on public properties only, your ipAddressServer is a static field (aka class variable) and not a property, so it won't be used. It's also failing at following proper naming conventions.
Your mess of a binding is the old style static binding, use {Binding Path=(w:Communication.IpAddressServer)} instead (after you fix #1, of course). w is the relevant XAML namespace definition.
Static properties don't have standard notifications for change, since static classes can't implement interfaces (for what I hope are obvious reasons). Instead WPF uses a convention-based approach of using a public static event PropertyChangedEventHandler StaticPropertyChanged and call that to notify changes. It's not clear if you want your property to be mutable, but you mentioned the change notification mechanism explicitly, so just throwing it out there.

point one is wrong because 1. ipAddressServer is a not a variable (not defined inside method), it is a class member (field) and 2. {Binding} extension requires properties for Path, but source can vary - e.g. {StaticResource} or smth `static` referenced via {x:Static} extension. and 3. {x:Static} extension work with `static` fields just fine, it is very useful for enums — ASh, Jun 30 '22 at 19:49

Wpf Two-way data binding doesn't work with static classes

1 Answers1