ViewModel is partially null after POST - asp.net-mvc

Question

I have an MVC 4 App where i have a ViewModel which has a couple of collections. During a POST the collections are null but the other fields are populated. Code attached please help.
View Model
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
namespace BAQueryTool.Models
{
public class QueryDefinition
{
[Key]
public int ID { get; set; }
[Display(Name = "Query Name")]
[MaxLength(32)]
[Required(ErrorMessage = "Query name is required.")]
public string Name { get; set; }
[Display(Name = "Query String")]
[Required(ErrorMessage = "Query string is required.")]
[DataType(DataType.MultilineText)]
[MaxLength(8192)]
public string QueryString { get; set; }
[NotMapped]
[Display(Name = "Query String")]
[MaxLength(175)]
public string QueryStringShort
{
get
{
string s = string.Empty;
if (this.QueryString != null)
{
s = this.QueryString.Trim();
if (s.Length >= 172)
{
return this.QueryString.Substring(0, 172) + "...";
}
}
return s;
}
}
[Display(Name = "Query Parameters")]
public virtual ICollection<QueryParameter> QueryParameters { get; set; }
}
public class RunQueryDefinition
{
public QueryDefinition QueryDefinition { get; set; }
[Display(Name = "Run Query Parameters")]
public virtual ICollection<RunQueryParameter> RunQueryParameters { get; set; }
}
}
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel.DataAnnotations.Schema;
namespace BAQueryTool.Models
{
public enum ParameterDataType
{
Date, String
}
public class QueryParameter
{
[Key]
public int ID { get; set; }
public int QueryDefinitionID { get; set; }
[Display(Name = "Parameter Name")]
[Required(ErrorMessage = "Parameter name is required.")]
[MaxLength(32)]
public string Name { get; set; }
[Display(Name = "Parameter Type")]
[Required(ErrorMessage = "Parameter name is required.")]
public ParameterDataType DataType { get; set; }
}
public class RunQueryParameter : QueryParameter
{
[Display(Name = "Parameter Value")]
[Required(ErrorMessage = "Parameter name is required.")]
public string Value { get; set; }
}
}
Controller
` `// GET: /QueryDefinition/Run/5
public ActionResult Run(int? id)
{
if (id == null)
{
return new HttpStatusCodeResult(HttpStatusCode.BadRequest);
}
QueryDefinition querydefinition = db.QueryDefinitions.Find(id);
if (querydefinition == null)
{
return HttpNotFound();
}
RunQueryDefinition runQueryDefinition = new RunQueryDefinition();
runQueryDefinition.QueryDefinition = querydefinition;
runQueryDefinition.RunQueryParameters = new List<RunQueryParameter> { };
foreach (var param in querydefinition.QueryParameters)
{
RunQueryParameter rqp = new RunQueryParameter();
rqp.ID = param.ID;
rqp.QueryDefinitionID = param.QueryDefinitionID;
rqp.Name = param.Name;
rqp.DataType = param.DataType;
rqp.Value = Convert.ToString(DateTime.Now.ToShortDateString());
runQueryDefinition.RunQueryParameters.Add(rqp);
}
return View(runQueryDefinition);
}
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Run(RunQueryDefinition parameterList)
{
DateTime BeginDate;
DateTime EndDate;
try
{
//QueryDefinition querydefinition = db.QueryDefinitions.Find(id);
if (ModelState.IsValid)
{
return RedirectToAction("Index");
}
}
catch (RetryLimitExceededException)
{
//Log the error
ModelState.AddModelError("", "Unable to save changes. Try again, and if the problem persists see your system administrator.");
}
return View();
}
View
#model BAQueryTool.Models.RunQueryDefinition
#{
ViewBag.Title = "Run Query";
}
<h2>Run Query Definition '#Html.DisplayFor(model => model.QueryDefinition.Name)'</h2>
#using (Html.BeginForm("Run", "QueryDefinition", FormMethod.Post, null))
{
#Html.AntiForgeryToken()
<div class="form-horizontal">
<hr />
<dl class="dl-horizontal">
<dt>
#Html.DisplayNameFor(model => model.RunQueryParameters)
</dt>
<dd>
<table class="table">
<tr>
<th>Parameter Name</th>
<th>Parameter Data Type</th>
<th>Parameter Value</th>
</tr>
#foreach (var item in Model.RunQueryParameters)
{
<tr>
<td>
#Html.DisplayFor(modelItem => item.Name)
</td>
<td>
#Html.DisplayFor(modelItem => item.DataType)
</td>
<td>
#Html.EditorFor(modelItem => item.Value)
</td>
</tr>
}
</table>
</dd>
</dl>
<div class="form-group">
<div class="col-md-offset-1 col-md-10">
<input type="submit" value="Run Query" class="btn btn-default" />
</div>
</div>
</div>
}
<div>
#Html.ActionLink("Back to List", "Index")
</div>
#section Scripts {
#Scripts.Render("~/bundles/jqueryval")
}
The main class is the QueryDefinition class. There is a Index page which lists out all the query definitions. When the user clicks on Run link the Run page is generated and populated with the QueryDefinitions for an Id. The QueryParameters Collection is also populated as well as the RunQueryParameters collection. When the user enters a value for the Column Value and clicks on Run Query a POST occurs. In Debug I noticed that the RunQueryDefinitions parameterList parameter was not fully populated, particularly the collections QueryParameters and RunQueryParameters.
Any suggestion ?

Answer 1

Do not use foreach loop, use for loop instead so that indexed values of collection can get posted:
#for(int i = 0; i < Model.RunQueryParameters.Count; i++)
{
<tr>
<td>
#Html.DisplayFor(modelItem => Model.RunQueryParameters[i].Name)
</td>
<td>
#Html.DisplayFor(modelItem => Model.RunQueryParameters[i].DataType)
</td>
<td>
#Html.EditorFor(modelItem => Model.RunQueryParameters[i].Value)
</td>
</tr>
}
See how model binding works in this article.