{"id":434,"date":"2010-04-14T14:04:23","date_gmt":"2010-04-14T18:04:23","guid":{"rendered":"http:\/\/www.ikriv.com\/blog\/?p=434"},"modified":"2010-04-14T14:04:23","modified_gmt":"2010-04-14T18:04:23","slug":"wpf-context-menu-on-list-item","status":"publish","type":"post","link":"https:\/\/ikriv.com\/blog\/?p=434","title":{"rendered":"WPF: Context menu on list item"},"content":{"rendered":"

I am using WPF and MVVM. I have a Window and a view model attached to it via Datacontext<\/code>. The window has a listbox, and its items have context menu. I am using DelegateCommand<\/code> in my view model, and I want to bind a menu items in the context menu to this command.<\/p>\n

First trouble is, by default the menu item is bound to the DataContext<\/code> of the list box item, which may or may not have knowledge of the whole view model.<\/p>\n

Second trouble is, context menu is not part of the visual tree, so referring to the main window via FindAncestor<\/code> or ElementName=...<\/code> will not work.<\/p>\n

You can get to the object immediately containing the context menu via the PlacementTarget<\/code> property, but then you will need an ancestor of this object (“window”), and there is no built-in way to find an ancestor of a property.<\/p>\n

An (almost) working solution that I found on the Internet after hours of search was to store the data context in some property of the PlacementTarget<\/code> – they used Tag<\/code> for this purpose.<\/p>\n

The “almost” part lies in the fact that if your command has CanExecute()<\/code> method, the command parameter passed to it is sometimes null<\/code> (see here<\/a>).<\/p>\n

<Window Name=\"MainWindow\"<\/b><\/font> ...>\n    <Grid>\n        <ListBox ItemsSource=\"{Binding Items}\">\n            <ListBox.ItemTemplate>\n                <DataTemplate>\n                    <StackPanel Orientation=\"Horizontal\"\n                               Tag=\"{Binding DataContext, ElementName=MainWindow}\"<\/b><\/font>>\n\t\t\t...\n                        <StackPanel.ContextMenu>\n                             <MenuItem Header=\"do it\"\n    Command=\"{Binding PlacementTarget.Tag.MyCommand, RelativeSource={RelativeSource AncestorType=ContextMenu}}\"<\/b><\/font>\n    CommandParameter=\"{Binding}\"<\/b><\/font>>\n                        <\/StackPanel.ContextMenu>\n                    <\/StackPanel>\n                <\/DataTemplate>\n            <\/ListBox.ItemTemplate>\n        <\/ListBox>\n    <\/Grid>\n<\/Window><\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
I am using WPF and MVVM. I have a Window and a view model attached to it via Datacontext. The window has a listbox, and its items have context menu. […]<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"Layout":"","footnotes":""},"categories":[12],"tags":[],"class_list":["entry","author-ikriv","post-434","post","type-post","status-publish","format-standard","category-wpf"],"_links":{"self":[{"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/434","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=434"}],"version-history":[{"count":0,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=\/wp\/v2\/posts\/434\/revisions"}],"wp:attachment":[{"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=434"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=434"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ikriv.com\/blog\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=434"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}