c# - defining bindings for elements in a collection in xaml wont work -

i have simple control collection of elements. want add elements in xaml , bind element.

however when bind bar.value in xaml never works. minimal example:

[contentproperty("bars")] public class foocontrol : control {     private observablecollection<ibar> _bars = new observablecollection<ibar>();     public observablecollection<ibar> bars { { return _bars; } } }  public interface ibar {     string value { get; } }  public class bar : dependencyobject, ibar {     public static readonly dependencyproperty valueproperty = dependencyproperty.register("value", typeof(string), typeof(bar), new propertymetadata("<not set>"));     public string value     {         { return (string)getvalue(valueproperty); }         set { setvalue(valueproperty, value); }     } } 

<window x:class="wpftestapplication.mainwindow"         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"         xmlns:this="clr-namespace:wpftestapplication"         xmlns:sys="clr-namespace:system;assembly=mscorlib"         title="mainwindow" height="200" width="1000">      <window.resources>         <style targettype="this:foocontrol">             <setter property="template">                 <setter.value>                     <controltemplate targettype="this:foocontrol">                         <itemscontrol itemssource="{binding bars, relativesource={relativesource templatedparent}}">                             <itemscontrol.itemtemplate>                                 <datatemplate>                                     <textblock text="{binding value}"/>                                 </datatemplate>                             </itemscontrol.itemtemplate>                         </itemscontrol>                     </controltemplate>                 </setter.value>             </setter>         </style>     </window.resources>      <window.datacontext>         <sys:string>from datacontext</sys:string>     </window.datacontext>     <grid>         <this:foocontrol>             <this:bar value="directly set"/>             <this:bar value="{binding source=from_binding_source}"/>             <this:bar value="{binding}"/>             <this:bar value="{binding text, elementname=sometextblock}"/>         </this:foocontrol>         <textblock text="from textbox" name="sometextblock" visibility="collapsed"/>     </grid> </window> 

output

directly set from_binding_source "<not set>" "<not set>" 

debug output

system.windows.data error: 2 : cannot find governing frameworkelement or frameworkcontentelement target element. bindingexpression:path=text; dataitem=null; target element 'bar' (hashcode=26568931); target property 'value' (type 'string')

any suggestion how work?

my current workaround define bindings in code lot more code , looking @ xaml not obvious bindings exists. (see answer workaround code)

dont know if helps but

[contentproperty("bars")] public class foocontrol : control {    private observablecollection<object> _bars = new observablecollection<object>();    public observablecollection<object> bars { { return _bars; } } } 

xaml

  <this:foocontrol>         <this:bar value="directly set"/>         <this:bar value="{binding source=from_binding_source}"/>         <textblock text="{binding}"/>         <textblock text="{binding text, elementname=sometextblock}"/>     </this:foocontrol> 

you desired result