asp.net mvc - MVC Model not updating -

the model

class address {     public string street { get; set; }     public string city { get; set; }     public string state { get; set; }     public string zip { get; set; } } 

the controller action

[httppost] public actionresult getaddress(address model) {     if (!string.isnullorempty(model.zip))     {         model.city = getcitybyzip(model.zip);     }     return view(model); } 

the view

<div class="formrow">     @html.labelfor(model => model.city)     @html.textboxfor(model => model.city)      @html.validationmessagefor(model => model.city) </div> <div class="formrow">      @html.labelfor(model => model.state)     @html.dropdownlistfor(model => model.state, (ienumerable<selectlistitem>)viewbag.states, new { style = "width:217px;" })      @html.validationmessagefor(model => model.state)  </div>  <div class="formrow">     @html.labelfor(model => model.zip)     @html.textboxfor(model => model.zip)      @html.validationmessagefor(model => model.zip) </div> 

the problem whenever city being modified, never gets reflected on view. during debugging, model.city contains correct value doesn't show on view. simple @html.textboxfor(model => model.city) doesn't display correct model.city value.

htmlhelpers model values model state , not model when update , return model. in order update , return model, add line of code in post method:

modelstate.clear(); 

or set value of city in modelstate itself:

modelstate["city"].value = getcitybyzip(model.zip);