ag_e_parser_bad_property_value Silverlight Binding Page Title
XAML:
<navigation:Page ... Title="{Binding Name}">
C#
public TablePage()
{
this.DataContext = new Table()
{
Name = "Finding Table"
};
InitializeComponent();
}
Getting a ag_e_parser_bad_property_value error in InitializeCompone开发者_高级运维nt at the point where the title binding is happening. I've tried adding static text which works fine. If I use binding anywhere else eg:
<TextBlock Text="{Binding Name}"/>
This doesn't work either.
I'm guessing it's complaining because the DataContext object isn't set but if I put in a break point before the InitializeComponent I can confirm it is populated and the Name property is set.
Any ideas?
You can only use data binding on properties that are supported by DependencyProperty
. If you take a look at the docs for TextBlock
for example you will find that the Text
property has a matching TextProperty
public static field of type DependencyProperty
.
If you look at the docs for Page
you will find that there is no TitleProperty
defined, the Title
property is therefore not a dependency property.
Edit
There is no way to "override" this however you could create an attached property:-
public static class Helper
{
#region public attached string Title
public static string GetTitle(Page element)
{
if (element == null)
{
throw new ArgumentNullException("element");
}
return element.GetValue(TitleProperty) as string;
}
public static void SetTitle(Page element, string value)
{
if (element == null)
{
throw new ArgumentNullException("element");
}
element.SetValue(TitleProperty, value);
}
public static readonly DependencyProperty TitleProperty =
DependencyProperty.RegisterAttached(
"Title",
typeof(string),
typeof(Helper),
new PropertyMetadata(null, OnTitlePropertyChanged));
private static void OnTitlePropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
Page source = d as Page;
source.Title = e.NewValue as string;
}
#endregion public attached string Title
}
Now your page xaml might look a bit like:-
<navigation:Page ...
xmlns:local="clr-namespace:SilverlightApplication1"
local:Helper.Title="{Binding Name}">
Add the following to MyPage.xaml.cs:
public new string Title
{
get { return (string)GetValue(TitleProperty); }
set { SetValue(TitleProperty, value); }
}
public static readonly DependencyProperty TitleProperty =
DependencyProperty.Register("Title",
typeof(string),
typeof(Page),
new PropertyMetadata(""));
Once you add this property (dependency property) to your code behind, your code will work as normal.
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