So, idea was to have to listbox where one list box I will fill with data from MySQL, and in another with data from XML.

This is example is maybe not good, since I don't have model, I just wanted to play with autofac on a simplest possible way.

So here are my interfaces: 

public interface IMyTree
{
	List<string> Read(List<string> listMyElements);
}
public interface IReadMyTree
{
	List<string> ReadXml();
	List<string> ReadMySql();
}

Here is the class which will actually return 

public class DoMytree : IMyTree
{
	public List<string> Read(List<string> listMyElements)
	{
		return listMyElements;
	}
}

Note that this class basically does nothing, that is because I don't have model, so I couldn't pass list of elements, for example, because structure is not same as structure from mySql.

Now, here is example of ReadMySql method: 

public class MyReader : IReadMyTree
{
	private readonly IMyTree _output;
	public MyReader(IMyTree output)
	{
		this._output = output;
	}

	public List<string> ReadMySql()
	{
		string MyConString =
		"SERVER=server;" +
		"DATABASE=db;" +
		"UID=user;" +
		"PASSWORD=pass;Convert Zero Datetime=True";

		string sql = "select * from jos_categories";

		try
		{
			var connection = new MySqlConnection(MyConString);
			var cmdSel = new MySqlCommand(sql, connection);

			connection.Open();

			MySqlDataReader dataReader = cmdSel.ExecuteReader();

			var pom = new List<string>();

			while (dataReader.Read())
			{
				object bugId = dataReader["title"];
				pom.Add(bugId.ToString());
			}

			return _output.Read(pom);
		}
		catch (Exception e)
		{
			MessageBox.Show("Error: " + e);
		}
		return null;
	}	
}

Note line: return _output.Read(pom); little bit of nonsense I agree :) I just wanted to follow dependency injection... This example is just for learning, remember ;) 

 Interesting thing to notice are lines: 

var connection = new MySqlConnection(MyConString);
var cmdSel = new MySqlCommand(sql, connection);

connection.Open();

MySqlDataReader dataReader = cmdSel.ExecuteReader();

var pom = new List<string>();

while (dataReader.Read())
{
	object bugId = dataReader["title"];
	pom.Add(bugId.ToString());
}

Here you can see how to fill list of strings from mySql, example how to connect to mySql you find here.

Autofac registration: 

public class ReadMySqlTreeViewAutofacViewModel
{
	public static List<string> ReadMySql()
	{
		var scope = MainWindow.Container.BeginLifetimeScope();
		var writer = scope.Resolve<IReadMyTree>();
		return writer.ReadMySql();
	}
	
	public List<string> TreeMySqlViewModels { get; set; }
	
	public ReadMySqlTreeViewAutofacViewModel()
	{
		var builder = new ContainerBuilder();
		builder.RegisterType<MyReader>().As<IReadMyTree>();
		builder.RegisterType<DoMytree>().As<IMyTree>();
		MainWindow.Container = builder.Build();

		TreeMySqlViewModels = ReadMySql();
	}
}

XAML:

<Window x:Class="ReadXmlTreeViewAutofac.View.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:system="clr-namespace:System;assembly=mscorlib"
        xmlns:viewModel="clr-namespace:ReadXmlTreeViewAutofac.ViewModel"
        Title="MainWindow" Height="350" Width="525">
    <Window.Resources>
        <viewModel:TreeViewModel x:Key="TreeViewModel" />
        <viewModel:ReadMySqlTreeViewAutofacViewModel x:Key="ReadMySqlTreeViewAutofacViewModel" />
    </Window.Resources>
    <TabControl>
        <TabItem Header="Read from Xml">
            <Grid DataContext="{StaticResource TreeViewModel}" OverridesDefaultStyle="True">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*"/>
                </Grid.ColumnDefinitions>
                <Grid.RowDefinitions>
                    <RowDefinition Height="*"/>
                </Grid.RowDefinitions>
                <TreeView Grid.Row="0" Grid.Column="0" Name="TvXml" ItemsSource="{Binding Path=TreeXmlViewModels}"/>
            </Grid>
        </TabItem>
        <TabItem Header="Read from MySql">
            <Grid OverridesDefaultStyle="True" DataContext="{StaticResource ReadMySqlTreeViewAutofacViewModel}">
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="*"/>
                </Grid.ColumnDefinitions>
                <Grid.RowDefinitions>
                    <RowDefinition Height="*"/>
                </Grid.RowDefinitions>
                <TreeView Grid.Row="0" Grid.Column="0" Name="TvMySql" ItemsSource="{Binding Path=TreeMySqlViewModels}"/>
            </Grid>
        </TabItem>        
    </TabControl>
</Window>

Things to notice in XAML are lines:

xmlns:viewModel="clr-namespace:ReadXmlTreeViewAutofac.ViewModel"

This is namespace which we will use, and lines:

<viewModel:TreeViewModel x:Key="TreeViewModel" />
<viewModel:ReadMySqlTreeViewAutofacViewModel x:Key="ReadMySqlTreeViewAutofacViewModel" />

These are classes which we will use to bind them with our trees, and finally tree binding:

<TreeView Grid.Row="0" Grid.Column="0" Name="TvXml" ItemsSource="{Binding Path=TreeXmlViewModels}"/>

Note that TreeXmlViewModels is property which I am registering it in autofac registration part, also note that I am preparing that property in line TreeXmlViewModels = ReadXml();

Example application you can download from here.

Github is here.