CODEWITHSUNDEEP
c#wpfxamlmvvmuser-controls
Tomtom
Tomtom

Reputation: 9394

Bind property of childcontrol to parentcontrol

I have a UserControl (Parent) in which is another UserControl (Child). I want to Bind a property in the Child-Control to a property in the Parent-Control. Both UserControls are developed within MVVM. My question now is, how do I access the property of the child-control in the xaml of the parent-control?

Do I have to do something in the code-behind of the child-control or is there another way?

I have an interface called IPerson which looks like:

public interface IPerson
{
  string Firstname {get;set;}
  string Lastname {get;set;}
}

The parent-control (PersonsView) has a TreeView on the left side and on the right side there's the child-control (PersonView).

The XAML of Persons-View is:

<UserControl x:Class="ScM.Contents.View.PersonsView"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:viewModel="clr-namespace:ScM.Contents.ViewModel"
             xmlns:view="clr-namespace:ScM.Contents.View"
             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">
    <UserControl.DataContext>
        <viewModel:PersonsViewModel />
    </UserControl.DataContext>
    <UserControl.Resources>
        <ResourceDictionary>
            <ResourceDictionary.MergedDictionaries>
                <ResourceDictionary Source="/ScM.Interface;component/GUI/ScMStyles.xaml" />
            </ResourceDictionary.MergedDictionaries>
        </ResourceDictionary>
    </UserControl.Resources>
    <Grid>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="200" />
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="*" />
        </Grid.ColumnDefinitions>
        <Grid.RowDefinitions>
            <RowDefinition Height="*"/>
        </Grid.RowDefinitions>
        <view:PersonsTreeView Grid.Column="0" Margin="2"
                             OpenPupil="{Binding DataContext.OpenPersonCommand, RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}"
                             Persons="{Binding DataContext.Persons, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged, 
            RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}" />
        <GridSplitter Grid.Column="1" Width="2" ShowsPreview="True" VerticalAlignment="Stretch"
                      HorizontalAlignment="Center" Margin="0,2" />

        <view:PersonView Grid.Column="2" Margin="2"></view:PersonView>

    </Grid>
</UserControl>

The Person-View consist only of labels and textboxes. The PersonViewModel looks like:

internal class PersonViewModel : ViewModelBase
{
    private readonly PersonModel _personModel;

    private IPerson _person;

    public PersonViewModel()
    {
        _personModel = new PersonModel();
    }

    public IPerson Person
    {
        get { return _person; }
        set
        {
            _person = value;
            OnPropertyChanged();
        }
    }
}

Upvotes: 0

Views: 342

Answers (1)

franssu
franssu

Reputation: 2430

You can either name your parent control to point to it using ElementName

<ParentControl x:Name=ParentControl>
   <ChildControl SomeChildControlProperty="{Binding SomeParentControlProperty,
                                            ElementName=ParentControl}"/>
</ParentControl>

or you can use RelativeSource with FindAncestor :

<ParentControl>
   <ChildControl SomeChildControlProperty="{Binding SomeParentControlProperty,
          RelativeSource={RelativeSource FindAncestor,
                          AncestorType={x:Type ParentControl}}}"/>
</ParentControl>

I didn't test this code though so the syntax might not be exactly right

Upvotes: 1

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