c# - How do I use XAML to bind a DatagridComboBoxColumn to a ViewModel property that isn't in the DataGrid's ItemsSource? -

what i'm attempting

• i have datagrid that's bound list called filestoadd, part of viewmodel.
• i have combobox column on datagrid.
• i bind combobox's selected item documenttype property of filestoadd list item.
• but, have list of available choices come availabledocumenttypes, property of viewmodel itself, not of filestoadd list.

the xaml

<datagrid itemssource="{binding filestoadd}" height="100" scrollviewer.horizontalscrollbarvisibility="auto" scrollviewer.verticalscrollbarvisibility="auto" maxheight="100" autogeneratecolumns="false" visibility="{binding filesarequeued, converter={staticresource booltovisconverter}}">     <datagrid.resources>         <app:bindingproxy x:key="proxy" data="{binding}"/>     </datagrid.resources>     <datagrid.columns>         <datagridtextcolumn header="file uploaded as" binding="{binding filedisplaytext}"/>         <datagridtextcolumn header="size" binding="{binding filesizeintext}"/>         <datagridcomboboxcolumn itemssource="{binding availabledocumenttypes}" header="document type" visibility="{binding data.documenttypesarerequired, converter={staticresource booltovisconverter}, source={staticresource proxy} }">         </datagridcomboboxcolumn>     </datagrid.columns> </datagrid> 

update 1: xaml i'm trying + datacontext clarification

per kevin's suggestion, tried:

<datagridcomboboxcolumn itemssource="{binding datacontext.availabledocumenttypes, relativesource={relativesource findancestor, ancestortype={x:type window }}}" header="document type" visibility="{binding data.documenttypesarerequired, converter={staticresource booltovisconverter}, source={staticresource proxy} }"/> 

also tried:

<datagridcomboboxcolumn itemssource="{binding path=datacontext.availabledocumenttypes, relativesource={relativesource findancestor, ancestortype={x:type window }}}" header="document type" visibility="{binding data.documenttypesarerequired, converter={staticresource booltovisconverter}, source={staticresource proxy} }"/> 

but receive error can't found.

fyi, datacontext set in following way:

in xaml:

<window x:class="veuploader.wpf.views.mainwindow"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"         xmlns:app="clr-namespace:veuploader.wpf"          xmlns:d="http://schemas.microsoft.com/expression/blend/2008"         xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:ignorable="d"         title="{binding windowtitle}" sizetocontent="widthandheight"         datacontext="{staticresource uploaderviewmodel}"         allowdrop="true"    > 

in code (so can dependency injection):

public mainwindow() {     var uploaderviewmodel = new uploaderviewmodel(objectfactory.getinstance<ivedocumentservice>(), objectfactory.getinstance<iargumentsettingsretriever>(), objectfactory.getinstance<ivebudgetservice>());     resources["uploaderviewmodel"] = uploaderviewmodel;       initializecomponent(); } 

i don't have compiler in front of me, believe syntax this:

{binding datacontext.myproperty, relativesource={relativesource mode=findancestor,                               ancestortype={x:type myparentcontrol}}} 

edit: doing testing of own, reason datagridcomboboxcolumn somehow cannot find item source, if template own combo box column, works fine. not sure why is, may acceptable work around.

<window x:class="wpftest.mainwindow"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"         title="mainwindow" height="350" width="525">     <grid>         <datagrid itemssource="{binding filestoadd}" >             <datagrid.columns>                 <datagridtemplatecolumn header="document type">                     <datagridtemplatecolumn.celltemplate>                         <datatemplate>                             <combobox                                 itemssource=                                 "{binding datacontext.availabledocumenttypes,                                  relativesource={relativesource findancestor,                                  ancestortype={x:type window }}}"/>                         </datatemplate>                     </datagridtemplatecolumn.celltemplate>                 </datagridtemplatecolumn>             </datagrid.columns>         </datagrid>     </grid> </window>