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I'm currently dabbling in WPF with C# the teachers i have for it know how to use windows forms, but not much about WPF. I can see that it's a bit of a different way to work with the GUI, but it seems solid.

While following a small crash course, I was trying to add a class as the datacontext for the MainWindow by using the XAML, but i seem unable to do it correctly. I've seen quite a few posts about it on here, but none of the things seem quite the same as what I'm experiencing. Here's My XAML

<Window x:Class="WPFTest.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:WPFTest"
    mc:Ignorable="d"
    Title="MainWindow" Height="350" Width="525">
<Window.DataContext>
    <local:AddressBookViewModel />
</Window.DataContext>
<Grid x:Name="WPFTest">
    <Button x:Name="btnNewContact" Content="Create a New Contact" HorizontalAlignment="Left" Margin="10,273,0,0" VerticalAlignment="Top" Width="209"/>
    <Label x:Name="lblName" Content="Name:" HorizontalAlignment="Left" Margin="259,129,0,0" VerticalAlignment="Top"/>
    <Label x:Name="lblEmail" Content="E-Mail:" HorizontalAlignment="Left" Margin="259,160,0,0" VerticalAlignment="Top"/>
    <Label x:Name="lblPhone" Content="Phone:" HorizontalAlignment="Left" Margin="259,191,0,0" VerticalAlignment="Top"/>
    <TextBox x:Name="txtName" HorizontalAlignment="Left" Height="23" Margin="327,133,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120"/>
    <TextBox x:Name="txtEmail" HorizontalAlignment="Left" Height="23" Margin="327,164,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120"/>
    <TextBox x:Name="txtPhone" HorizontalAlignment="Left" Height="23" Margin="327,195,0,0" TextWrapping="Wrap" Text="TextBox" VerticalAlignment="Top" Width="120"/>
    <ListBox x:Name="lbxContacts" HorizontalAlignment="Left" Height="204" Margin="10,53,0,0" VerticalAlignment="Top" Width="209"/>
</Grid>

And my Class which i would like to use as a ViewModel:

    namespace WPFTest
{
    public class AddressBookViewModel
    {
        public AddressBookViewModel()
        {

        }

        protected List<Contact> contacts = new List<Contact>();

        protected Contact selectedContact = null;

        public List<Contact> Contacts
        {
            get
            {
                return contacts;
            }
            set
            {
                contacts = value;
            }
        }

        public Contact SelectedContact
        {
            get
            {
                return selectedContact;
            }
            set
            {
                selectedContact = value;
            }
        }
    }
}

This, however, just gives me an error: 

  The name "AddressBookViewModel" does not exist in the namespace "clr-namespace:WPFTest".

I Simply do not comprehend what is going wrong. It seems to me that AddressBookViewModel does indeed very much exist in this namespace, but Visual Studio clearly disagrees.

Can someone please explain to me the problem?

I understand that i can bind the Datacontext in the code behind, however, i can see the value in being able to do it in the XAML

rasmus91
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  • Have you tried just building/rebuilding the project? Xaml-Errors sometimes only resolve after building/rebuilding... – Philip W Oct 13 '15 at 10:18
  • Yes, it doesn't change anything. – rasmus91 Oct 13 '15 at 10:21
  • Did you add the ViewModel class to the solution in its own file or did you add it to the code file of the Window? – Emond Oct 13 '15 at 10:24
  • Do you have other errors? Sometimes (or rather often) xaml error messages are missleading. Fix everything and try rebuild. I don't see errors in your definition, it's similar to [this](http://stackoverflow.com/a/23714054/1997232), thus should work. Unless there are some invisible characters in class name. – Sinatr Oct 13 '15 at 10:29
  • Does your project build without errors if you comment out those DataContext lines in your XAML file? – Pieter Witvoet Oct 13 '15 at 11:04
  • Hey! ViewModel is in it's own file (in the project) no errors other than the "does not exist in namespace" one My projects builds without errors if i comment out DataContext lines. – rasmus91 Oct 13 '15 at 11:23

1 Answers1

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Your code seems to work fine here: enter image description here

The error message you pasted (...does not exist in the namespace...) is the result of a build-time error. The 'Contact' class you are using in the model may have an error? Something does, in any case.

dylansweb
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