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c#wpfxamltype-conversion
JMK
JMK

Reputation: 28069

Visibility type-converter not being called

I have a test WPF Window with the below XAML:

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:wpfApplication2="clr-namespace:WpfApplication2"
        xmlns:test="clr-namespace:WpfApplication2.Properties"
        DataContext="{Binding Path=TestClass}"
        Title="MainWindow" Height="350" Width="525" >

    <Window.Resources>
        <wpfApplication2:TestTypeConverter x:Key="TestConverter"/>
    </Window.Resources>

    <Grid>
        <Grid Visibility="{Binding TestProperty, Converter={StaticResource TestConverter}, ConverterParameter='nottest'}">
            <Label Content="Test Label"></Label>
        </Grid>
    </Grid>
</Window>

I have a test type-converter class which is below:

using System;
using System.Globalization;
using System.Windows.Data;

namespace WpfApplication2
{
    class TestTypeConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            var valueToTest = (string) value;
            var parameterToCheck = (string) parameter;

            return valueToTest == parameterToCheck ? System.Windows.Visibility.Visible : System.Windows.Visibility.Collapsed;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            return value;
        }
    }
}

TestClass is below:

using System.ComponentModel;
using System.Runtime.CompilerServices;
using WpfApplication2.Annotations;

namespace WpfApplication2
{
    public class TestClass : INotifyPropertyChanged
    {
        public TestClass()
        {
            TestProperty = "test";
        }

        private string _testProperty;
        public string TestProperty
        {
            get { return _testProperty; }
            set
            {
                if (_testProperty == value)
                {
                    return;
                }
                _testProperty = value;
                OnPropertyChanged();
            }
        }


        public event PropertyChangedEventHandler PropertyChanged;

        [NotifyPropertyChangedInvocator]
        protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
        {
            var handler = PropertyChanged;
            if (handler != null) handler(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

The visibility property isn't being affected by the type-converter, and the Convert method itself isn't even being called (I have placed a breakpoint which is not being hit).

What am I doing wrong?

Thanks

Upvotes: 1

Views: 4150

Answers (3)

Gerald G.
Gerald G.

Reputation: 81

Just omit the name of property altogether if you do not have a datacontext and it will work, The following wroked for me.

Visibility="{Binding Converter={StaticResource myTestConverter}}"

// see how Converter keyword is followed by Binding keyword and I did not specify property name after Binding keyword.

Upvotes: 0

Shrinand
Shrinand

Reputation: 351

Create a resource for the converter parameter (as shown in the snippet below) and use the resource as converter parameter instead of the literal

<Window x:Class="WpfApplication2.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
        xmlns:wpfApplication2="clr-namespace:WpfApplication2"
        xmlns:test="clr-namespace:WpfApplication2.Properties"
        xmlns:sys="clr-namespace:System;assembly=mscorlib"
        DataContext="{Binding Path=TestClass}"
        Title="MainWindow" Height="350" Width="525" >
    <Window.Resources>
        <wpfApplication2:TestTypeConverter x:Key="TestConverter"/>
<sys:String x:Key="converterParam">nottest</sys:String>
    </Window.Resources>

    <Grid>
        <Grid Visibility="{Binding TestProperty, Converter={StaticResource TestConverter}, ConverterParameter={StaticResource converterParam}">
            <Label Content="Test Label"></Label>
        </Grid>
    </Grid>
</Window>

Upvotes: 1

thumbmunkeys
thumbmunkeys

Reputation: 20764

Your binding seems wrong:

 Visibility="{Binding 'test', Converter={StaticResource TestConverter}, ConverterParameter='nottest'}"

change it to:

 Visibility="{Binding test, Converter={StaticResource TestConverter}, ConverterParameter='nottest'}"

If the property test does not exist, no converter will be called

Upvotes: 2

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