Passing values to IValueConverter

Question

I have a ListView that has a Grid with two columns and many rows. Each row has a TextBlock in each column with each Text property binded to a value in ListView's ItemSource. I need to do some converting of the text in the second TextBlock depending on the value in the first TextBlock. How can I get the value of the first text box to the converter?

Here is what I have so far:

XAML:

<UserControl.Resources>
    <local:ValueStringConverter x:Key="valueStringConverter" />
</UserControl.Resources>

<ListView Name="theListView" ItemsSource="{Binding ItemCollection}" SelectedItem="{Binding SelectedItem}" ScrollViewer.HorizontalScrollBarVisibility="Disabled" Grid.Row="1" >
    <ListView.ItemTemplate>
        <DataTemplate>
            <Grid>
                <Grid.RowDefinitions>
                    <RowDefinition Height="Auto" />
                </Grid.RowDefinitions>

                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto" />
                    <ColumnDefinition Width="*" />
                </Grid.ColumnDefinitions>

                <TextBlock Text="{Binding Path=Key}" Grid.Column="0" Margin="0,0,10,0" />
                <TextBlock Text="{Binding Path=Value, Converter={StaticResource valueStringConverter}}" TextWrapping="Wrap" Grid.Column="1" />
            </Grid>
        </DataTemplate>
    </ListView.ItemTemplate>
</ListView>

Code of ValueStringConverter:

public class ValueStringConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        string name = (string)value;
        name = name.Replace("$$", " ");
        name = name.Replace("*", ", ");
        name = name.Replace("##", ", ");

        return value;
    }

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

score 6 · Accepted Answer · edited Jul 08 '14 at 08:21

You can't pass more than one value to the "regular" value converter. You could go with IMultiValueConverter and define the binding as MultiBinding.

Or you can create a IValueConverter that takes the entire object in the DataContext, cast the object to its type, take the Value and Key and return the string you need.

On your second textblock define the binding as

<TextBlock Text="{Binding Converter={StaticResource valueStringConverter}"/>

And your converter as:

public class ValueStringConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        MyDataContextObjectType obj= (MyDataContextObjectType)value;
        var name= obj.Name;
        var key = obj.Key;
        //here you have both Name and Key, build your string and return it
        //if you don't know the type of object in the DataContext, you could get the Key and Name with reflection
        name = name.Replace("$$", " ");
        name = name.Replace("*", ", ");
        name = name.Replace("##", ", ");

        return value;
    }

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

score 5 · Answer 2 · answered Jun 04 '13 at 20:32

Try multi-binding. You'll need an IMultiValueConverter:

public class MultiValueConverter : IMultiValueConverter
{
    public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
    {
        var key   = (string)values[0];
        var value = (string)values[1];

        // replace with appropriate logic
        var result = key + ": " + value;

        return result;
    }

    public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

and slightly modified XAML:

<TextBlock Text="{Binding Path=Key}" Grid.Column="0" Margin="0,0,10,0" />
<TextBlock TextWrapping="Wrap" Grid.Column="1">
    <TextBlock.Text>
        <MultiBinding Converter={StaticResource valueStringConverter}>
            <Binding Path="Key" />
            <Binding Path="Value" />
        </MultiBinding>
    </TextBlock.Text>
</TextBlock>

score 0 · Answer 3 · answered Jun 04 '13 at 20:33

0

Bind to the instance, not the property (value in this case). Then you will have access to both Key and Value in the converter.

answered Jun 04 '13 at 20:33

trydis

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– Pitka Nov 21 '16 at 12:37

Passing values to IValueConverter

3 Answers3

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