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Not controlled exception in WPF XAML: The specified conversion is not valid

I have a MVVM WPF application. I have below converter:
public class PrintIconVisibilityValueConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
if (values[0] == null || values[1] == null) return Visibility.Collapsed;
int item1 = (int)values[0];
string item2 = (string)values[1];
if (item1 > 0 || !string.IsNullOrEmpty(item2))
{
return Visibility.Visible;
}
else
{
return Visibility.Collapsed;
}
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
From my view I do:
<Window.Resources>
<classes:PrintIconVisibilityValueConverter x:Key="PrintIconVisibilityValueConverter"/>
</Window.Resources>
then I have an image in this view:
<Image Source="/MyImages;component/Images/PrintIco.png"
Height="15" Margin="20 0 5 0">
<Image.Visibility>
<MultiBinding Converter="{StaticResource PrintIconVisibilityValueConverter}">
<Binding Path="Item1" />
<Binding Path="Item2" />
</MultiBinding>
</Image.Visibility>
</Image>
Item1 and Item2 are public properties in view model:
private string _item2 = string.Empty;
public string Item2
{
get
{
return _item2;
}
set
{
if (_item2 == value) return;
_item2 = value;
OnPropertyChanged("Item2");
}
}
private int _item1;
public int Item1
{
get
{
return _item1;
}
set
{
if (_item1 == value) return;
_item1 = value;
OnPropertyChanged("Item1");
}
}
It compiles correctly and I can execute the application without problems but in design time, the view is not show, an error says Not controlled exception and points to the line:
int item1 = (int)values[0];
within PrintIconVisibilityValueConverter class.
Below the screenshots of the exception shown on view:

Some suggestions;
Call the GetIsInDesignMode method in your converter and return immediately if it returns true:
public class PrintIconVisibilityValueConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter, CultureInfo culture)
{
if (DesignerProperties.GetIsInDesignMode(new DependencyObject()))
return Visibility.Visible;
...
}
public object[] ConvertBack(object value, Type[] targetTypes, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
Set the DataContext in XAML:
<Window.DataContext>
<local:ViewModel />
</Window.DataContext>
Set the design time data context:
<Window ... d:DataContext ="{d:DesignInstance {x:Type local:ViewModel}, IsDesignTimeCreatable=True}">
Or Disable XAML UI designer

Philosophy on Binding to Parameters in WPF

So I'm trying to build out a project that will allow a user to type some text into a textbox on the left side of the form and that will filter out the available items from my datasource list.
<Label Content="Enter item name below"></Label>
<TextBox Name="SearchTermTextBox" TabIndex="0" Text="" />
I was under the impression I could bind to the datasource the list then use a converter to filter out the items that were unlike the string.
<ListBox DataContext="{Binding Colors}">
<ListBox.ItemsSource>
<MultiBinding Converter="{StaticResource FilterTextValueConverter}" ConverterParameter="{Binding ElementName=SearchTermTextBox, Path=Text}" />
</ListBox.ItemsSource>
<ListBox.ItemTemplate>
//etc...
</ListBox.ItemTemplate>
</ListBox>
However, you can't bind to an elementname in the converterparameter unless you use something called a dependency property.
Edit: Seeing as I've created confusion with the code above, here's the converter I'm trying to bind:
public class FilterTextValueConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
var trackedColors = value as List<Colors>;
if (trackedColors != null)
return (trackedColors).Where(item => item.ColorName.Contains(parameter.ToString())).ToList();
return null;
}
public object ConvertBack(object value, Type targetTypes, object parameter, CultureInfo culture)
{
throw new NotImplementedException();
}
}
public class Colors
{
public String ColorName;
public String Description;
}
What is wrong with my approach here? Clearly I'm angering the WPF gods since this is a fairly straightforward operation but I'm being denied it on principle. Any help would be appreciated.

Simple binding with converter will work here, no need for MultiBinding.
<ListBox ItemsSource="{Binding Path=Text, ElementName=SearchTermTextBox,
Converter="{StaticResource FilterTextValueConverter}">
......
</ListBox>
Assuming FilterTextValueConverter is implementing IValueConverter, you can access text from value passed to Convert method.
public class FilterTextValueConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
string text = value.ToString(); // TEXT for textBox can be accessed here.
return new List<string>(); // Return filtered list from here.
}
public object ConvertBack(object value, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
return Binding.DoNothing;
}
}
UPDATE
In case you want to pass multiple bindings to converter, use IMultiValueConverter because ConverterParameter is not Dependency property, hence cannot be bound.
XAML
<ListBox DataContext="{Binding Colors}">
<ListBox.ItemsSource>
<MultiBinding Converter="{StaticResource FilterTextValueConverter}">
<Binding/>
<Binding ElementName="SearchTermTextBox" Path="Text"/>
</MultiBinding>
</ListBox.ItemsSource>
</ListBox>
Converter
public class FilterTextValueConverter : IMultiValueConverter
{
public object Convert(object[] values, Type targetType, object parameter,
System.Globalization.CultureInfo culture)
{
var trackedColors = values[0] as List<Colors>;
if (trackedColors != null && !String.IsNullOrEmpty(values[1].ToString()))
return (trackedColors).Where(item =>
item.ColorName.Contains(values[1].ToString())).ToList();
return null;
}
public object[] ConvertBack(object value, Type[] targetTypes,
object parameter,
System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}

I continued looking into this issue well after the accepted answer was posted and working for me. What I discovered is that it's a fairly trivial task to wrap the control you're trying to get a new dependencyproperty out of to allow for proper binding.
I will not be accepting my own answer to this determined so much later, but this seems (in my amateur opinion) like a much more elegant solution than adding a converter despite being a bit more complex:
Note that this is for a new dependency on the caretindex property of a textbox, not for the original question on binding, but it just requires some smart renaming to get it working ;).
public class TextBoxDependencyWrapper : TextBox
{
public static readonly DependencyProperty CaretIndexProperty = DependencyProperty.Register(
"CaretIndex", typeof (int), typeof (TextBoxDependencyWrapper), new FrameworkPropertyMetadata(default(int), FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, CaretIndexChanged ));
protected override void OnKeyUp(KeyEventArgs e) //Event that changes the property we're trying to track
{
base.OnKeyUp(e);
CaretIndex = base.CaretIndex;
}
protected override void OnKeyDown(KeyEventArgs e) //Event that changes the property we're trying to track
{
base.OnKeyDown(e);
CaretIndex = base.CaretIndex;
}
public new int CaretIndex
{
get { return (int) GetValue(CaretIndexProperty); }
set { SetValue(CaretIndexProperty, value); }
}
}

binding images in listbox

I have a listbox that is populated from a datatable. I want each item to have a specific image on listbox, but I want to set the image depending of an id that each item has.
for example , I have :
Products
Orange
Apple
ID
1
2
and the images are named: Item.1.png , Item.2.png
So, in my listbox,where I have apple, I will have next to it the image named: Item.2.png.
My problem is that I don't know how could I do a conditional binding . I don't want to have on my template hundreds of lines that are doing this for each item. I need to do this using a condition, like : if(product.id==1), Image.Source=Item.1.png.
Is there any way to do this in wpf?

It sounds to me like you need an IdToImageConverter that will decides which Image should be shown dependant on the value of the Id property. Something like this should do the trick:
[ValueConversion(typeof(int), typeof(ImageSource))]
public class IdToImageConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (value.GetType() != typeof(int) || targetType != typeof(ImageSource)) return false;
int id = (int)value;
if (id < 0) return DependencyProperty.UnsetValue;
string imageName = string.Empty;
switch (id)
{
case 1: imageName = "Item.1.png"; break;
case 2: imageName = "Item.2.png"; break;
}
if (imageName.IsEmpty()) return null;
return string.Format("/AppName;component/ImageFolderName/{0}", imageName);
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
{
return DependencyProperty.UnsetValue;
}
You could then use it in your ListBox.ItemTemplate something like this:
<YourConvertersXmlNamespacePrefix:IdToImageConverter x:Key="IdToImageConverter" />
...
<ListBox ItemsSource="{Binding Items}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<Image Source="{Binding Id, Converter={StaticResource
IdToImageConverter}}" />
<TextBlock Text="{Binding Name}" Margin="5,0,0,0" />
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>

As I understand your question, every object in the listbox has an ID property, where you want the image to be item.ID.png.
You could use a converter in your binding to do this. So in your listbox template, you can have something like:
// ... Listbox template
<Image Source={Binding pathToItemID, Converter={StaticResource MyConverter}/>
// ... Remaining ListBox template
You will need to add the converter to the UserControl's resources:
<UserControl.Resources>
<xmlnsPointingToConverter:MyConverter x:Key="MyConverter"/>
</UserControl.Resources>
Then add a MyConverter class which implements IValueConverter:
public class MyConverter : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return string.Format("item.{0}.png", value);
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new NotImplementedException();
}
}

Set converter on TextBox

I need to calculate/change form of input between textbox to its bindable source. The way i trying to achive this, is with help of converters.
Converter:
public class ParameterConverter : IValueConverter
{
public object Convert(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
if (value == null)
return string.Empty;
string originalParameValue = value.ToString();
string fixedParameterValue = string.Format("#_{0}", originalParameValue);
return fixedParameterValue;
}
public object ConvertBack(object value, System.Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
throw new System.NotImplementedException();
}
}
XAML:
<Window.Resources>
<converters:ParameterConverter x:Key="parameterConverter" />
</Window.Resources>
<Grid>
<TextBox Text="{Binding ParameterA, Converter={StaticResource parameterConverter}}"/>
</Grid>
The problem is, that converter is functioning only once. Is it approach correct (i mean with converter) or there are another approaches ?

Perhaps the binding Mode is not two way, and did your property fire property changed.

Does your data context implement INotifyPropertyChanged and is PropertyChanged being called whenever ParameterA is changed? It seems as if nobody is notifying the textbox that it needs to update its contents.

WPF RadioButton InverseBooleanConverter not working

I have two RadioButtons which I am binding to a boolean property in the ViewModel. Unfortunately I am getting an error in the converter because the 'targetType' parameter is null.
Now I wasn't expecting the targetType parameter coming through to be null (I was expecting True or False). However I noticed that the IsChecked property of the RadioButton is a nullable bool so this kind of explains it.
Can I correct something in the XAML or should I be changing the solution's existing converter?
Here's my XAML:
<RadioButton Name="UseTemplateRadioButton" Content="Use Template"
GroupName="Template"
IsChecked="{Binding UseTemplate, Mode=TwoWay}" />
<RadioButton Name="CreatNewRadioButton" Content="Create New"
GroupName="Template"
IsChecked="{Binding Path=UseTemplate, Mode=TwoWay, Converter={StaticResource InverseBooleanConverter}}"/>
This is the existing converter I am using solution wide InverseBooleanConverter:
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if ((targetType != typeof(bool)) && (targetType != typeof(object)))
{
throw new InvalidOperationException("The target must be a boolean");
}
return !(((value != null) && ((IConvertible)value).ToBoolean(provider)));
}

You need to change the converter, or what's probably even better, use a new converter.
[ValueConversion(typeof(bool?), typeof(bool))]
public class Converter : IValueConverter
{
#region IValueConverter Members
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (targetType != typeof(bool?))
{
throw new InvalidOperationException("The target must be a nullable boolean");
}
bool? b = (bool?)value;
return b.HasValue && b.Value;
}
public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
{
return value;
}
#endregion
}