Select first item in Silverlight combobox using MVVM pattern -

this first foray in mvvm , i've encountered following issue:

i've got viewmodel:

  public list<workcellgroupinfo> workcellgroupinfocollection     {                 {             return _workcellgroupinfocollection;         }         set         {             _workcellgroupinfocollection = value;             notifypropertychanged( "workcellgroupinfocollection" );              selectedworkcellgroup = _workcellgroupinfocollection.firstordefault();         }     }      public workcellgroupinfo selectedworkcellgroup     {                 {             return _selectedworkcellgroup;         }         set         {             _selectedworkcellgroup = value;             notifypropertychanged( "selectedworkcellgroup" );         }     } 

and xaml:

<combobox x:name="workcellgroup"  itemssource="{binding workcellgroupinfocollection}"  selecteditem="{binding selectedworkcellgroup, mode=twoway}"  displaymemberpath="name"> 

on first load combobox gets populated data can't first item selected. doing wrong?

the workcellgroupinfo derived filterbase class:

public abstract class filterbase {     public string id     {         get;         set;     }      public string name     {         get;         set;     } } 

you need assign value selectedworkcellgroup property that.

in viewmodel's constructor, write following code:

if(workcellgroupinfocollection.any())  {     selectedworkcellgroup = workcellgroupinfocollection.first(); } 

edit:

following works me:

xaml:

<grid x:name="layoutroot"       background="white">     <border horizontalalignment="center"             verticalalignment="center">         <combobox x:name="workcellgroup"                   itemssource="{binding workcellgroupinfocollection}"                   selecteditem="{binding selectedworkcellgroup, mode=twoway}"                   displaymemberpath="name" />     </border> </grid> 

code behind:

public partial class comboboxselecteditemtest : usercontrol {     public comboboxselecteditemtest()     {         initializecomponent();          datacontext = new comboboxselecteditemtestviewmodel();     } }  public abstract class filterbase {     public string id     {         get;         set;     }      public string name     {         get;         set;     } }  public class workcellgroupinfo : filterbase { }  public class workcellgroupinfocollection : observablecollection<workcellgroupinfo> { }  public class comboboxselecteditemtestviewmodel : inotifypropertychanged {     public workcellgroupinfocollection workcellgroupinfocollection { get; set; }      public comboboxselecteditemtestviewmodel()     {         workcellgroupinfocollection = new workcellgroupinfocollection();          (int = 0; < 25; i++)         {             workcellgroupinfocollection.add(new workcellgroupinfo()             {                 id = string.format("id #{0}", + 1),                 name = string.format("name #{0}", + 1)             });         }          selectedworkcellgroup = workcellgroupinfocollection.first();     }      private workcellgroupinfo _selectedworkcellgroup;     public workcellgroupinfo selectedworkcellgroup     {                 {             return _selectedworkcellgroup;         }         set         {             _selectedworkcellgroup = value;             raisepropertychanged("selectedworkcellgroup");         }     }      public event propertychangedeventhandler propertychanged;     protected void raisepropertychanged(string propertyname)     {         propertychangedeventhandler temp = propertychanged;         if (temp != null)         {             temp(this, new propertychangedeventargs(propertyname));         }     } }