wpf controls - How to add WPF Behavior in the code behind -

i trying find way add behavior in code, able add in xaml.

this how adding behavior in xaml grid, selecteditems dp in behavior , data bind view model selected items property. listening grid collection changed event , updating dp in turns notify view mode of selected items

/// <summary> /// dependency property selecteditems /// </summary> public static readonly dependencyproperty selecteditemsproperty =         dependencyproperty.register("selecteditems",          typeof(inotifycollectionchanged), typeof(multiselectbehavior),          new propertymetadata(null));  associatedobject.selecteditems.collectionchanged += gridselecteditems_collectionchanged; 

<i:interaction.behaviors>                     <behaviors:multiselectbehavior selecteditems="{binding selecteditems}"/> </i:interaction.behaviors> 

what need create behavior in code behind. doing in constructor of window contains grid, not working, viewmodel selected items property not getting updated.

var multiselectbehavior = new multiselectbehaviorsingleton(); bindingoperations.setbinding(this.backupsgrid, multiselectbehavior.selecteditemsproperty,      new binding()     {         source = this.datacontext,         path = new propertypath("selecteditems"),         mode = bindingmode.oneway     }); interaction.getbehaviors(this.backupsgrid).add(multiselectbehavior); 

try this:

var multiselectbehavior = new multiselectbehavior(); bindingoperations.setbinding(multiselectbehavior, multiselectbehavior.selecteditemsproperty, new binding("selecteditems")); interaction.getbehaviors(this.backupsgrid).add(multiselectbehavior);