CODEWITHSUNDEEP
silverlightmvvmbind
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Aaaaaaaa

Reputation: 2114

How to bind a list of child objects in Silverlight MVVM

In Silverlight, MVVM I have to create a property window, but I have just a List<AProperty> object, where AProperty is an abstract class with some child classes.

I want to bind it to a Silverlight control (but to which one?), with some conditions:

  1. some child-properties must be shown as a textbox, some as a checkbox, and some as a combobox. It comes from the dynamic type.
  2. the AProperty class has a PropertyGroup and a Name field. The order must be alphabetic (PropertyGroup > Name)

Any idea or working example?

My code:

    public abstract class AProperty {
        private String _Name;
        private String _Caption;
        private String _PropertyGroup;

        public String Name {
            get { return _Name; }
            set { _Name = value; }
        }

        public String Caption {
            get { return _Caption; }
            set { _Caption = value; }
        }

        public String PropertyGroup {
            get { return _PropertyGroup; }
            set { _PropertyGroup = value; }
        }
    }
    List<AProperty> Properties;

And the xaml:

<ListBox ItemsSource="{Binding ... Properties ...}">
  <!-- Here order the items -->
  <ListBox.ItemTemplate>
    <DataTemplate>
      <StackPanel Orientation="Horizontal">
        <TextBlock Width="250"
                    Text="{Binding Path=Caption}" />

        <!-- And here need I a textbox, or a checkbox, or a combobox anyway -->
      </StackPanel>
    </DataTemplate>
  </ListBox.ItemTemplate>
</ListBox>

I've found value converters just for a control attribute, not for a whole stackpanel content.

Upvotes: 1

Views: 800

Answers (3)

Aaaaaaaa
Aaaaaaaa

Reputation: 2114

Thanks Jesse and Andy, here is the solution

The converter:

public class PropertyConverter : IValueConverter {
        public object Convert( object value, Type targetType, object parameter, System.Globalization.CultureInfo culture ) {
            Binding ValueBinding = new Binding() {
                Source = value,
                Path = new PropertyPath( "Value" ),
                Mode = BindingMode.TwoWay
            };

            Binding EditableBinding = new Binding() {
                Source = value,
                Path = new PropertyPath( "Editable" ),
                Mode = BindingMode.TwoWay
            };

            if( value is PropertyString ) {
                TextBox tb = new TextBox();
                tb.SetBinding( TextBox.TextProperty, ValueBinding );
                tb.SetBinding( TextBox.IsEnabledProperty, EditableBinding );

                return tb;
            } else if( value is PropertyBoolean ) {
                CheckBox cb = new CheckBox();
                cb.SetBinding( CheckBox.IsCheckedProperty, ValueBinding );
                cb.SetBinding( CheckBox.IsEnabledProperty, EditableBinding );

                return cb;
            } ....

            return null;
        }

        public object ConvertBack( object value, Type targetType, object parameter, System.Globalization.CultureInfo culture ) {
            throw new NotImplementedException();
        }
    }

And the xaml code:

...
xmlns:Converters="clr-namespace:MyConverters"
...

<UserControl.Resources>
    <Converters:PropertyConverter x:Key="PropertyInput"/>
</UserControl.Resources>

...

<ListBox ItemsSource="{Binding Path=ItemProperties.GeneralProperties}">
            <ListBox.ItemTemplate>
                <DataTemplate>
                    <Grid>
                        <Grid.ColumnDefinitions>
                            <ColumnDefinition Width="180" />
                            <ColumnDefinition Width="320" />
                        </Grid.ColumnDefinitions>

                        <TextBlock Text="{Binding Name}" Grid.Column="0" />
                        <ContentPresenter Content="{Binding Converter={StaticResource PropertyInput}}" Grid.Column="1" />
                    </Grid>
                </DataTemplate>
            </ListBox.ItemTemplate>
        </ListBox>

Two artikel: http://shawnoster.com/blog/post/Dynamic-Icons-in-the-Silverlight-TreeView.aspx http://www.silverlightshow.net/items/Silverlight-2-Getting-to-the-ListBoxItems-in-a-ListBox.aspx

Upvotes: 0

jes
jes

Reputation: 331

The ValueConverter Andy mentions should work. Underneath your Textblock have a ContentPresenter, and bind it's Content.

Content={Binding , ConverterParameter={StaticResource NAMEOFCONVERTER}}.

The binding to the property is empty since you already have the object you want as the context. Then just check the type and return the control you want. you may want to make usercontrol's that are just Textblocks, etc. so that you can set the binding there, otherwise you will have to do it in code.

Upvotes: 1

Andy May
Andy May

Reputation: 4070

You could use a value converter to check what Type the object is and return the correct control type.

Do you have any sample code so I could give a better example?

Upvotes: 1

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