WPF Element Binding

Question

I have two controls within my UserControl where I bind to the exact same object using Element Binding:

AllowNext="{Binding ElementName=MainGrid, Path=DataContext.CanContinue}"

On the first control it works fine but on the second I get a binding exception:

System.Windows.Data Error: 4 : Cannot find source for binding with reference 'ElementName=MainGrid'. BindingExpression:Path=DataContext.CanContinue; DataItem=null; target element is 'WizardPage' (Name='DeductionPage'); target property is 'AllowNext' (type 'Boolean')

I have also tried using RelativeSource binding on the second control:

AllowNext="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Grid}}, Path=DataContext.CanContinue}"

But this also gives me an error.

Does anyone know what this might be?

--

Here is the simplified control:

<Grid Name="MainGrid">
    <w:Wizard Name="MyWizard" w:Designer.PageIndex="1" DataContext="{Binding ElementName=MainGrid, Path=DataContext.Policy}" >
        <w:WizardPage Header="Main Member" MaxHeight="600" AllowNext="{Binding ElementName=MainGrid, Path=DataContext.CanContinue}" Name="MainPage">
        </w:WizardPage>
        <w:WizardPage Name="DeductionPage" Header="Policy Details" AllowBack="False" AllowNext="{Binding ElementName=MainGrid, Path=DataContext.CanContinue}">
        </w:WizardPage>
    </w:Wizard>
</Grid>

Now as I mentioned, MainPage binds fine, whereas the DeductionPage does not bind at all and gets the supplied error. The DataContext of MainGrid is set from code behind:

    public void SetDataContext(object o)
{
  MainGrid.DataContext = o;
}

Could you please post the source for your UserControl? My first guess is that this may be a DataContext issue? — Dutts

terry terry · Accepted Answer · 2013-02-18T08:31:16

I bet it's the MainGrid which is the binding source is not in the logical tree of your binding target.

WPF Element Binding

2 Answers