Control Content

You have probably seen what happens if you put a button control into the content zone of an Avalonia UI window.

info

The concept of the zones of an Avalonia UI control is discussed here.

For example:

<Window xmlns="https://github.com/avaloniaui"
        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"
        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
        x:Class="MySample.MainWindow"
        Title="MySample">
  <Button HorizontalAlignment="Center" >Hello World!</Button>
</Window>

The window displays the button - in this case centred both horizontally (specified) and vertically (by default). It looks like this:

And if you put a string into the window content zone, for example:

<Window xmlns="https://github.com/avaloniaui"
        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"
        mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
        x:Class="MySample.MainWindow"
        Title="MySample">
  Hello World!
</Window>

The window will display the string:

But what happens if you try to display an object from a class that you have defined in the window?

For example, using the class definition Student

namespace MySample
{
    public class Student
    {
        public string FirstName { get; set;} = String.Empty;
        public string LastName { get; set;} = String.Empty;
    }
}

And the XML namespace local defined as the MySample namespace (from above), you can define a student object in the content zone of the window; as follows:

<Window xmlns="https://github.com/avaloniaui"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="using:MySample"
        x:Class="MySample.Views.MainWindow">
  <local:Student FirstName="Jane" LastName="Deer"/>
</Window>

But you will see only the fully-qualified class name for the student object:

This is not very helpful! It happens because Avalonia UI has no definition of how to display an object of class Student - and it is not a control - so it falls back on the .ToString() method, and all you see is the fully-qualified class name.

On the next page you will see one of the ways you can specify how to display an object created from a class that you have defined (not a control or a simple string).