WPF: Menu Items only bind command parameters once.
- by Aran Mulholland
Ive noticed this a couple of times when using menus with commands, they are not very dynamic, check this out. I am creating a menu from a collection of colours, I use it to colour a column in a datagrid. Anyway when i first bring up the menu (its a context menu) the command parameter binding happens and it binds to the column that the context menu was opened on. However the next time i bring it up it seems wpf caches the menu and it doesnt rebind the command parameter. so i can set the colour only on the initial column that the context menu appeared on.
I have got around this situation in the past by making the menu totally dynamic and destroying the collection when the menu closed and forcing a rebuild the next time it opened, i dont like this hack. anyone got a better way?
<MenuItem
Header="Colour"
ItemsSource="{Binding RelativeSource={RelativeSource AncestorType={x:Type local:ResultEditorGrid}}, Path=ColumnColourCollection}"
ItemTemplate="{StaticResource colourHeader}" >
<MenuItem.Icon>
<Image
Source="{StaticResource ColumnShowIcon16}" />
</MenuItem.Icon>
<MenuItem.ItemContainerStyle>
<Style
TargetType="MenuItem"
BasedOn="{StaticResource systemMenuItemStyle}">
<!--Warning dont change the order of the following two setters
otherwise the command parameter gets set after the command fires,
not mush use eh?-->
<Setter
Property="CommandParameter">
<Setter.Value>
<MultiBinding>
<MultiBinding.Converter>
<local:ColumnAndColourMultiConverter/>
</MultiBinding.Converter>
<Binding RelativeSource="{RelativeSource AncestorType={x:Type DataGridColumnHeader}}" Path="Column"/>
<Binding Path="."/>
</MultiBinding>
</Setter.Value>
</Setter>
<Setter
Property="Command"
Value="{Binding RelativeSource={RelativeSource AncestorType={x:Type local:ResultEditorGrid}}, Path=ColourColumnCommand}" />
</Style>
</MenuItem.ItemContainerStyle>
</MenuItem>
