WPF binding to an observable collection with hash key as index - wpf

Question

The following code:
<UserControl x:Class="MyProgram.Views.MyControlContainer"
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"
xmlns:local="clr-namespace:MyProgram.Views"
xmlns:common_model="clr-namespace:MyProgram.Models;assembly=CommonTitan"
mc:Ignorable="d"
>
<Grid Background="White">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<local:MyControl x:Name="MyControl1" DataContext="{Binding MyControlCollection[8]}" Grid.Row="0" Grid.Column="0"/>
<local:MyControl x:Name="MyControl2" DataContext="{Binding MyControlCollection[9]}" Grid.Row="0" Grid.Column="1"/>
<local:MyControl x:Name="MyControl3" DataContext="{Binding MyControlCollection[10]}" Grid.Row="0" Grid.Column="2"/>
</Grid>
</UserControl>
Appropriately (as far as i can tell) binds me to the items that i specify in a collection. In real use it will use an observable dictionary and those indexes are hash values that i won't be able to hand code in. Is it possible to pass in the 2 known parameters into some sort of converter in order to get the hash? or even pass in the 2 values to the converter which will end up returning the item out of the observable dictionary?

Answer 1

You can pass 2 known value as converter parameters, for example:
<local:MyControl x:Name="MyControl1" DataContext="{Binding MyControlCollection, Converter={StaticResource CollectionConverter}, ConverterParameters='8.9'}" />
And in your converter class you can use it here, parse the parameter as string:
public class CollectionConverter: IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (parameter != null)
{
string[] param = (parameter as string).split('.');
if (int.Parse(param[0]) == 8)
return (value as ObservableCollection)[8];
else
return (value as ObservableCollection)[0];
}
return null;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new InvalidOperationException("cannot cast the value");
}
}