How to Expose a Control in XAML - wpf

Question

I'm new in WPF and I'm creating a control. This control contains a DataGrid and some other WPF controls.
I created my Control as below:
<UserControl x:Class="MyControls.MyControl"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="329" d:DesignWidth="535" >
<Grid>
<DataGrid Margin="6,25,6,35" Name="dataGrid" SelectionUnit="CellOrRowHeader" x:FieldModifier="public" HeadersVisibility="All"/>
<OtherControl HorizontalAlignment="Left" x:Name="otherControl" Height="34" VerticalAlignment="Bottom" Width="523" x:FieldModifier="private"/>
<Label Content="caption" Height="24" HorizontalAlignment="Left" Name="captionLabel" VerticalAlignment="Top" Foreground="#FF2626D1" x:FieldModifier="private"/>
</Grid>
</UserControl>
So, everything goes well so far, then I create a container UserControl which has in it my control created previously:
<UserControl x:Class="MyContainers.MyContainer"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="300" d:DesignWidth="300" xmlns:my="clr-namespace:MyControls">
<Grid>
<my:MyControl>
</my:MyControl>
</Grid>
What I can not do is the following:
<my:MyControl>
<my:MyControl.dataGrid>
</my:MyControl.dataGrid>
</my:MyControl>
I previously set the datagrid's property of FieldModifier as public in order to get access to it in another xaml, but it raises an error from visual studio.
I need to "expose" my dataGrid in order to be able to add columns and their styles.
I would like to be able to do something like this:
<my:MyControl.dataGrid.Columns >
<DataGridTextColumn />
<DataGridTextColumn />
...
<DataGridTextColumn />
</my:MyControl.dataGrid.Columns>
So, is not enough to set the datagrid's property of FieldModifier as public?
Do I need to do something else? How can I achieve this? Is this even possible?
I hope someone can help me. Thank you in advance.

Answer 1

You cannot access the child DataGrid as MyControl.dataGrid -- MyControl has no property named "dataGrid".
You might try adding a dependency property of type ObservableCollection<DataGridColumn> to MyControl, and modify the dataGrid columns whenever that collection changes.
EDIT:
Whipped together a quick example for you:
UserControl code:
public partial class UserControl1 : UserControl
{
public static readonly DependencyProperty ColumnsProperty = DependencyProperty.Register("Columns", typeof(ObservableCollection<DataGridColumn>), typeof(UserControl1));
public ObservableCollection<DataGridColumn> Columns
{
get { return (ObservableCollection<DataGridColumn>)GetValue(ColumnsProperty); }
set { SetValue(ColumnsProperty, value); }
}
public UserControl1()
{
Columns = new ObservableCollection<DataGridColumn>();
Columns.CollectionChanged += (s, a) =>
{
dataGrid.Columns.Clear();
foreach (var column in this.Columns)
dataGrid.Columns.Add(column);
};
InitializeComponent();
}
}
UserControl xaml:
<UserControl x:Class="WpfApplication1.UserControl1"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008">
<Grid>
<DataGrid x:Name="dataGrid" AutoGenerateColumns="False"/>
</Grid>
so you can use it like:
<Grid>
<l:UserControl1>
<l:UserControl1.Columns>
<DataGridTextColumn Header="Col1"/>
<DataGridTextColumn Header="Col2"/>
</l:UserControl1.Columns>
</l:UserControl1>
</Grid>