How to pass parameter to ContentTemplateSelector?

Question

I want the TemplateSelector to select a template based on the country. So, for MyDataTemplateSelector:SelectTemplate to receive the country I bind Content of ContentPresenter to CountriesComboBox. The problem is that the returned template is not bound to City or Streets. I think it happens because DataContext of the selected template is not bound to the ViewModel, and thus, bounded properties of the tamplate are not accessible.

I tried the code below, but in my opinion, it doesn't work since the Content of ContentPresenter is bound to CountriesComboBox and not to {Binding} as it should be. But, if I bind Content to {Binding}, I won't have access to the selected item of CountriesComboBox from TemplatrSelector.

So, how do I do this?

<DataGrid>
    <DataGrid.Resources>
        <DataTemplate x:Key="Readonly_CellEditingTemplate">
            <TextBlock Text="{Binding City}"/>
        </DataTemplate>
        <DataTemplate x:Key="Editable_CellEditingTemplate">
            <ComboBox ItemsSource="{Binding Streets}" />
        </DataTemplate>
        <local:MyDataTemplateSelector ReadonlyTemplate="{StaticResource Readonly_CellEditingTemplate}" EditableTemplate="{StaticResource Editable_CellEditingTemplate}" x:Key="MyDataTemplateSelector"/>
    </DataGrid.Resources>
    <DataGrid.Columns>
        <DataGridTemplateColumn Header="City">
            <DataGridTemplateColumn.CellTemplate>
                <DataTemplate>
                    <TextBlock Text="{Binding City}"/>
                </DataTemplate>
            </DataGridTemplateColumn.CellTemplate>
            <DataGridTemplateColumn.CellEditingTemplate>
                <DataTemplate>
                    <ContentPresenter x:Name="Presenter" Content="{Binding ElementName=CountriesComboBox, Path=SelectedIndex}" ContentTemplateSelector="{StaticResource MyDataTemplateSelector}" />
                </DataTemplate>
            </DataGridTemplateColumn.CellEditingTemplate>
        </DataGridTemplateColumn>
        </DataGrid.Columns>
    </DataGrid>

    <ComboBox Name="CountriesComboBox" ItemsSource="{Binding Countries}" />

Answer 1

I've found an answer in 3 years old post from Victor. Thanks Victor. I just need to add DataContext="{Binding RelativeSource={RelativeSource AncestorType=ContentControl},Path=DataContext}" in each DataTemplate.