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How to get collections on viewmodel on postback in MVC

In mvc most of the people will face problem how to bind view model list while post request. If a partial control is binding with a list and want to preserve the user input with view model list, most common issue is id/name is same. If the Id/Name are different only MVC engine can bind it with the model.

Please see the below example

Build the view/partial view in the following way. By keeping a row counter means all items will have unique names.

Suppose this partial view is coming inside a View Called MethodName.ASPX and is included inside the

Main Page


 using html.beginform()
[httpGet]

{
<%html.dropdownlist(model=>model.Test, new {onclick=Test(<%=model.Id%>);});
<.div id="dvPopulatePartialViewWithList"></.div>
}


Javascript function Test


function Test(id)
{
 $.ajax({
        type: "Get",
        data: "Id=" + Id,
        url: '/MyController/GetPartialViewListById',
        success: function (result) {
            $('#dvPopulatePartialViewWithList').html(result);
        }
    });
}


Controller Method


public actionresult GetPartialViewListById(int Id)
{
 try
{
  List list=GetListById(Id);

return renderPartial("MyPartialView",list);
}
catch(Exception ex)
{
throw new exception("error",ex);
}
}

PartialView   MyPartialView
<%@ Control Language="C#" Inherits="System.Web.Mvc.ViewUserControl>" %>
<%@ Import Namespace="External_ViewModel" %>

<%  int rowCounter = 0; //Keep track of unique value for binding to model list
%>
   

<%
           foreach (var model in Model)
           {
           
<%: Html.ValidationSummary(true)%>
<%: Html.Hidden("[" + rowCounter + "].Id", model.Id)%>
<%: Html.Hidden("[" + rowCounter + "].Name", Model.Name)%>

    <%= model.nameOfItem%>
    [
    <%= cav.Item%>
    ]



    <%: Html.TextBox("[" + rowCounter + "].Value", model.Value, new { Style = "width:140px;" })%>
 
    <%: Html.ValidationMessage("[" + rowCounter + "].Value", model.Value)%>
 
<% ++rowCounter;
           }  //end foreach  Loop
%>

In Controller create the action like this


[httpPost]
 public ActionResult MethodName(ViewModel model, List resultList)

        {
// when you submit the form resultList will have binded values
}

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