Binding a converterParameter value

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5.00/5 (1 vote)

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Hi all,
I have following xaml code where I am trying to bind converterParameter value:

C#

<Window.Resources>
    <ResourceDictionary>
        <local:ExpandedCategoryConverter x:Key="ExpandConverter"/>
        <Style TargetType="{x:Type propgrid:PropertyGridDataAccessorItem}">
            <Style.Triggers>
                <Trigger Property="DataAccessorType" Value="Category">
                    <Setter Property="IsExpanded">
                        <Setter.Value>
                            <MultiBinding Converter="{StaticResource ExpandConverter}">
                                <Binding Path="DisplayName"/>
                                <Binding Path="ExpandCategory"/>
                            </MultiBinding>
                        </Setter.Value>
                    </Setter>
                </Trigger>
            </Style.Triggers>
        </Style>  
    </ResourceDictionary>
</Window.Resources>

The problem is that I want to bind ExpandCategory not from TargetType="{x:Type propgrid:PropertyGridDataAccessorItem}", but from my viewModel.
How can I do that?
Thnx in advance

Posted 3-Jun-13 5:16am

Alexander Dymshyts

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Comments

koleraba 4-Jun-13 8:24am

Binding expression which defines just the 'Path' attribute always binds to DataContext of the current instnace. So as long DataContext of your PropertyGridDataAccessorItem contains the correct view-model this should work.

Alexander Dymshyts 4-Jun-13 8:37am

In my converter class in debug mode I get DisplayName fine, but ExpandCategory is - unset({DependencyProperty.UnsetValue}).
Any ideas how can I fix it?

koleraba 4-Jun-13 22:26pm

Do you get any notifications about failed bindings in the output window when you run the solution?

Alexander Dymshyts 5-Jun-13 3:00am

Yes, I have an error "Cannot find source for binding with reference 'ElementName=window'". I think it's because element ExpandCategory defined in my viewModel, and TargetType for my style is PropertyGridDataAccessorItem, so there are no such element ExpandCategory in PropertyGridDataAccessorItem. But how to solve this I have no idea right now

koleraba 5-Jun-13 11:06am

Sorry I can not say more without seeing more of the code, but it seems to me there is a problem how your binding are set up. If you use Binding ElementName=window it means that you do not bind to your data context but to another element in your visual tree. Try to find the reason for your failed binding and than go on from there.
Uros

Alexander Dymshyts 6-Jun-13 6:02am

Thank you for your help, I found where was the problem.

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Alexander Dymshyts · Accepted Answer · 2013-06-06T00:09:00

The solution was very simple - I just added RelativeSource to my binding in Mode = FindAncestor.
Code looks now so:

C#

<window.resources>
    <resourcedictionary>
        <style targettype="{x:Type propgrid:PropertyGridDataAccessorItem}">
            <style.triggers>
                <trigger property="DataAccessorType" value="Category">
                    <setter property="IsExpanded">
                        <setter.value>
                            <multibinding>
                                <multibinding.converter>
                                    <local:expandedcategoryconverter  />
                                </multibinding.converter>
                                <binding path="DisplayName" relativesource="{RelativeSource Self}" />
                                <binding path="ViewModel" relativesource="{RelativeSource Mode=FindAncestor, AncestorType=Window}" />
                            </multibinding>
                        </setter.value>
                    </setter>
                </trigger>
            </style.triggers>
        </style>  
    </resourcedictionary>
</window.resources>