c# - Binding from parents Viewmodel -

i have view has listbox in it. have listbox bound collection of listboxviewmodel property of mainviewmodel. have datatemplate listbox in im binding properties of listboxviewmodel. view contains listbox has datacontext set mainveiwmodel. how can bind properties of mainviewmodel in datatemplate of listbox has itemsource bound collection of listboxviewmodels?

this combobox in listbox datatemplate has itemsoucrce bound collection of listboxviewmodels. notice im trying bind mainviewmodel properties listboxviewmodel properties in datatemplate

      <listbox itemsource="{binding path=collectionoflistboxviewmodelsinmainviewmodel}"            <datatemplate>                .....                 <combobox margin="6"                           width="300"                           iseditable="true"                           itemssource="{binding path=mainviewmodelproperty}" //binding not working                           selecteditem="{binding listboxviewmodelproperty}"  //binding works                           text="{binding listboxviewmodelproperty, updatesourcetrigger=lostfocus}"/>   //binding works                 .....           </datatemplate>        </listbox> 

simplest way:

<yourwindow x:name="mywindow">  <listbox itemsource="{binding path=collectionoflistboxviewmodelsinmainviewmodel}"            <datatemplate>                .....                 <combobox margin="6"                           width="300"                           iseditable="true"                           itemssource="{binding elementname=mywindow, path=datacontext.mainviewmodelproperty}"                           selecteditem="{binding listboxviewmodelproperty}"  //binding works                           text="{binding listboxviewmodelproperty, updatesourcetrigger=lostfocus}"/>   //binding works                 .....           </datatemplate>        </listbox> </yourwindow> 

1) remember mywindow must have set datacontext mainviewmodel. can use ui element, doesn't have window. 2) second solution use relativesource instead of elementname.