WPF: Custom UserControl throwing an Exception

Question

I have created a UserControl and then use that control elsewhere but it always throws an exception.

Output:

A first chance exception of type 'System.ArgumentException' occurred in WindowsBase.dll

A first chance exception of type 'System.TypeInitializationException' occurred in WindowsBase.dll

Call Stack:

PresentationFramework.dll!System.Windows.Markup.XamlReader.RewrapException(System.Exception e, System.Xaml.IXamlLineInfo lineInfo, System.Uri baseUri) + 0x10 bytes

is the topmost call.

It's a basic UserControl with a ListBox inside it and has 3 DP, 2*DataTemplate and a IList for the ListBox's ItemsSource.

Where I use the UserControl I do it like this.

 <CustomUC:MyUserControl ItemsSource="{Binding SomeList}" > <CustomUC:MyUserControl.HeadTemplate> <DataTemplate> <StackPanel Orientation="Horizontal"> <TextBlock Text="{Binding Path=Name}" /> </StackPanel> </DataTemplate> </CustomUC:MyUserControl.HeadTemplate> </CustomUC:MyUserControl>

I am not even using one of the templates when trying it out and have tried to comment it out but still no luck.

Even when I'vcommented out all the code that could be throwing exceptions it still won't load.

 <UserControl x:Class="Myproject.CustomUC.MyUserControl" 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" mc:Ignorable="d" d:DesignHeight="300" d:DesignWidth="300"> <Grid> <ListBox ItemsSource="{Binding Path=Collection}"> <ListBox.ItemContainerStyle> <Style TargetType="ListBoxItem"> <Setter Property="Template"> <Setter.Value> <ControlTemplate TargetType="ListBoxItem"> <Border> <Grid> <Grid.RowDefinitions> <RowDefinition /> <RowDefinition /> </Grid.RowDefinitions> <ContentPresenter Name="Head" Visibility="Visible" ContentTemplate="{Binding Path=HeadTemplate}"/> </Grid> </Border> </ControlTemplate> </Setter.Value> </Setter> </Style> </ListBox.ItemContainerStyle> </ListBox> </Grid>

EDIT

Added info. The Visual Designer gives me this error:

Default value type does not match type of property 'HeadTemplate'.

Mark Staff · Accepted Answer · 2011-06-01 13:03:21Z

2

I think it could be the

<UserControl x:Class="Myproject.CustomUC:MyUserControl" ...

That is causing the problem. You've got a : between the CustomUC and the MyUserControl, it should be a .

For more details have a look at the MSDN page for x:Class

answered Jun 1, 2011 at 13:03

Mark Staff

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3 Comments

Ingó Vals Over a year ago

sorry that was a copy/paste error since I changed the name I accidentaly put a : intead of a . but in the original it's the correct .

Mark Staff Over a year ago

can you try changing <CustomUC:MyUserControl ItemsSource="{Binding SomeList}" > to <CustomUC:MyUserControl DataContext="{Binding SomeList}" > and then in the control <ListBox ItemsSource="{Binding }">

Ingó Vals Over a year ago

I found out what it is. I had some UIPropertyMetadata(0) parameter in the DP that came up when I did some shortcut. Didn't notice.

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