c# - Model not being updated when using a List -

i have model property of type list. use property show values on view. use foreach loop go through each item in list , displaying them using displayfor , textboxfor. part working fine; i've used textboxfor before , user entered text gets past model on submit. however, when using list, list null when form submitted. other properties in model updated , can access them correctly. preventing list binding , how can fix this?

modelinstrumentlistingdetail

public class modelinstrumentlistingdetail {     public int instrumenttagid { get; set; }     public string instrumenttagdescription { get; set; }      public list<modelinstrumentlistingitem> items { get; set; } } 

modelinstrumentlistingitem

public class modelinstrumentlistingitem {     public string field { get; set; }     public string label { get; set; } } 

view

@model gpc.models.modelinstrumentlistingdetail  @using (html.beginform("instrumentlistingadd", "home", formmethod.post, new { id = "instrumentlistingdetailform" })) {   <table>    <tr>     <td>          @html.textboxfor(m => m.instrumenttagdescription)     </td>    </tr>    @foreach (gpc.models.modelinstrumentlistingitem item in model.items)   {    <tr>       <td>           @html.displayfor(m => item.label)       </td>       <td>           @html.textboxfor(m => item.field)       </td>    </tr>    } </table> <input id="submitinstrumentlistingadd" name="submitinstrumentlistingadd" value="add" type="submit" class="savebutton" /> } 

controller

[httppost] public actionresult instrumentlistingadd(modelinstrumentlistingdetail model, string submitinstrumentlistingadd) {   ... } 

on submit, model posted controller has instrumentdescription value, items null. need figure out how fill items new values.

change loop so:

@for(int idx = 0;idx < model.items.count;idx++) {     <tr>          <td>             @html.displayfor(_ => model.items[idx].label)          </td>          <td>              @html.textboxfor(_ => model.items[idx].field)          </td>      </tr> } 

the reason works <input> elements generated so:

<input id="items_0_" name="items[0]" type="text" value="foo"> <input id="items_1_" name="items[1]" type="text" value="bar">

when post data, following in body:

items[0]:foo items[1]:bar 

the default asp.net mvc model binder pick these items request body , apply them viewmodel, in case modelinstrumentlistingdetail.items