How to pass a textbox value to child page textbox

Question

(all in wpf)

I have a login window with username and password. When a user logs in, the value of the username is passed on to another username.text textbox in the MainWindow. This I have successfully done by passing a string value in the form declaration. Same way you normally would in winforms.

Now the way i access my child pages are through links.

eg: Link DisplayName= "Home" Source="/Pages/Home.xaml" /> so child pages content are shown on the main window. as if the main window is a frame of some sort.

What I need now is that this username.text in the MainWindow has its value passed on to username.text textboxes in the child pages.

I am doing this so that the program will know which user is logging in ang can log who is making what changes to the database.

I understand that the most efficient method od doing this is through one way databinding. now this works in the same page... but it doesn't work in a different page and main window.

    <TextBox x:Name="username" Text="{Binding Text, ElementName=alias, Mode=OneWayToSource, UpdateSourceTrigger=PropertyChanged}" Height="19" VerticalAlignment="Top" HorizontalAlignment="Left" Width="211" FontSize="11"/>

    <TextBox x:Name="alias" Margin="186,64,0,0" Height="18" VerticalAlignment="Top" HorizontalAlignment="Left" Width="211" FontSize="11" ></TextBox>

Is there anyone that knows how to do this?

code for the MainWindow

    <mui:ModernWindow x:Class="Masca.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:mui="http://firstfloorsoftware.com/ModernUI"
    Title="Masca Database Admin" Height="800" Width="1280" IsTitleVisible="True"
    LogoData="F1 M 24.9015,43.0378L 25.0963,43.4298C 26.1685,49.5853 31.5377,54.2651 38,54.2651C 44.4623,54.2651 49.8315,49.5854 50.9037,43.4299L 51.0985,43.0379C 51.0985,40.7643 52.6921,39.2955 54.9656,39.2955C 56.9428,39.2955 58.1863,41.1792 58.5833,43.0379C 57.6384,52.7654 47.9756,61.75 38,61.75C 28.0244,61.75 18.3616,52.7654 17.4167,43.0378C 17.8137,41.1792 19.0572,39.2954 21.0344,39.2954C 23.3079,39.2954 24.9015,40.7643 24.9015,43.0378 Z M 26.7727,20.5833C 29.8731,20.5833 32.3864,23.0966 32.3864,26.197C 32.3864,29.2973 29.8731,31.8106 26.7727,31.8106C 23.6724,31.8106 21.1591,29.2973 21.1591,26.197C 21.1591,23.0966 23.6724,20.5833 26.7727,20.5833 Z M 49.2273,20.5833C 52.3276,20.5833 54.8409,23.0966 54.8409,26.197C 54.8409,29.2973 52.3276,31.8106 49.2273,31.8106C 46.127,31.8106 43.6136,29.2973 43.6136,26.197C 43.6136,23.0966 46.127,20.5833 49.2273,20.5833 Z"          
    ContentSource="/Pages/Home.xaml">

<Window.DataContext>
    <TextBox x:Name="username" Text="{Binding Text, ElementName=alias, Mode=OneWayToSource, UpdateSourceTrigger=PropertyChanged}" Height="19" VerticalAlignment="Top" HorizontalAlignment="Left" Width="211" FontSize="11"/>
</Window.DataContext>

code for the child page

  <UserControl x:Class="Masca.Mail.Configuration"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
         xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
         xmlns:mui="http://firstfloorsoftware.com/ModernUI"
         mc:Ignorable="d" 
         d:DesignHeight="800" d:DesignWidth="1280">



<Grid HorizontalAlignment="Left" Height="780" Margin="10,10,0,0" VerticalAlignment="Top" Width="1260">

    <TextBox x:Name="alias" Margin="186,64,0,0" Height="18" VerticalAlignment="Top" HorizontalAlignment="Left" Width="211" FontSize="11" ></TextBox>


</Grid>

that's the xaml for both the mainwindow and child page.

Answer 1

In you View model Expose static property as below

public class ViewModel
{
  private static ViewModel instance=new ViewModel();

  public static Viewmodel Instance
  {
     get
     {
        return instance;
     }
  }
} 

And in both the Xmal.cs(MainWindow.xmal.cs and ChildPage.Xmal.cs files in Constructor set the data context

    DataContext=Viewmodel.Instance

And change TextBinding in both Xmal as follows

  <TextBox x:Name="username" Text="{Binding PropertyInViewModel, UpdateSourceTrigger=PropertyChanged}" Height="19" VerticalAlignment="Top" HorizontalAlignment="Left" Width="211" FontSize="11"/>

  <TextBox x:Name="alias" Text="{Binding PropertyInViewModel, UpdateSourceTrigger=PropertyChanged} Margin="186,64,0,0" Height="18" VerticalAlignment="Top" HorizontalAlignment="Left" Width="211" FontSize="11" ></TextBox>

Answer 2

You may create a static class

public static class Credentials
{
    public static string username { get; set;}
}

Assign it during logon then you may call it in a base VM class or on each clase you need.