Question

I’ve created the following XAML, approximately (shortened for brevity):

<Window ...
    xmlns:Models="clr-namespace:Project.Presentation.Models;assembly=Project"
    ...>
    <Window.Resources>
        <Models:ProfileCollection x:Key="Profiles" />
    </Window.Resources>
</Window>

ProfileCollection is defined as, simply:

public class ProfileCollection : ObservableCollection<Profile>
{
    public ProfileCollection()
    {
        foreach (Profile p in Configuration.Instance.Profiles)
            this.Add(p);
    }
    // code that handles static added/removed events
}

This follows the requirements set forth in XAML and Custom Classes on MSDN.

However, when I try to compile I get this error:

error MC3074: The tag ‘ProfileCollection’ does not exist in XML namespace ‘clr-Project.Presentation.Models;assembly=Project’. Line 18 Position 7.

I’ve also tried:

<Window ...
    xmlns:SystemCollections="clr-namespace:System.Collections;assembly=mscorlib"
    ...>
    <Window.Resources>
        <SystemCollections:ArrayList x:Key="arrayList" />
    </Window.Resources>
</Window>

That works fine.

public class SomeList : ArrayList { public SomeList() { } }

I get the same error trying to use this object. It’s the same error as before.

<Models:SomeList x:Key="arrayList" />  <!-- MC3074 -->

Answer 1

Is 'ProfileCollection' class placed in the namespace 'Project.Presentation.Models? Also if XAML and class are both in 'Project' assembly, try to remove “assembly=Project” from xmlns declaration

Good luck 😉