asp.net mvc - MVC Passing ViewModel to @Html.Partial -

passing viewmodel @html.partial

have 2 viewmodels

public class registervm {   ... properties   public addressvm addressinformation { get; set; } //viewmodel }  public class addressvm {    public string street1 { get; set; }    public string street2 { get; set; }    public string postalcode { get; set; } } 

when loading main view using vm:

    @model viewmodels.registervm 

all field load. when add partial view , pass viewmodel

     @html.partial("_addressdetails", model.addressinformation) 

it fails error: exception details: system.nullreferenceexception: object reference not set instance of object. why fail?

the partial view _addressdetails expecting

         @model viewmodels.addressvm  

update

based on changes prashant,

when submitting information address information null. in controller:

    [httppost]     public actionresult register(registervm vm){      ...     //when viewing vm.addressinformation.street1 null. , there value     //is there different way of retrieving values partial view?     } 

thanks reading.

the error generated because property addressinformation null, , need initailize in parameterless constructor or in controller before pass view, example

public class registervm {   public registervm() // default constructor   {     addressinformation = new addressvm();   }   public addressvm addressinformation { get; set; }   .... } 

however usage means controls generated be

<input name="street1" .../> 

whereas need

<input name="addressinformation.street1" .../> 

in order bind model. can either make partial editortemplate (/views/shared/editortemplates/addressvm.cshtml) , use in main view as

@html.editorfor(m => m.addressinformation) 

or pass prefix partial additional viewdata

@html.partial("_addressdetails", model.addressinformation, new viewdatadictionary { templateinfo = new templateinfo { htmlfieldprefix = "addressinformation" }})