MVC form post model list - asp.net-mvc

Question

I have a Model that gets sent to a view. This model has List elements that are used to populate listboxes. In this view, I post to a controller action passing in my model as a parameter. On postback, I can see primitive types, but, can't seem to access the list. Here's my code:
Model:
public class ReportInfoViewModel
{
public int report_id { get; set; } = 0;
public string report_name { get; set; } = "";
public string report_path { get; set; } = "";
public string plaza_param { get; set; } = "y";
public List<FacilityViewModel> facilitieslist { get; set; } = new List<FacilityViewModel>();
}
public class FacilityViewModel
{
public string facility_id { get; set; }
public string facility_name { get; set; }
}
View:
#model CSC.ViewModels.ReportInfoViewModel
#using (Html.BeginForm("ViewReport", "Reports", Model, FormMethod.Post, new { target = "_blank" }))
{
if (#Model.plaza_param.ToString().ToLower().Equals("y"))
{
#Html.DevExpress().ListBox(
l =>
{
l.Name = "lstPlazaParam";
l.Width = Unit.Pixel(300);
l.Height = Unit.Pixel(120);
l.Properties.SelectionMode = ListEditSelectionMode.CheckColumn;
l.Properties.EnableSelectAll = true;
l.Properties.TextField = "facility_name";
l.Properties.ValueField = "facility_id";
l.SelectedIndex = 0;
l.Properties.ValueType = typeof(string);
l.Properties.ValidationSettings.RequiredField.IsRequired = true;
l.Properties.ValidationSettings.RequiredField.ErrorText = "Please select a Plaza";
l.Properties.ValidationSettings.ErrorText = l.Properties.ValidationSettings.RequiredField.ErrorText;
l.Properties.ValidationSettings.ErrorTextPosition = ErrorTextPosition.Bottom;
l.Properties.ValidationSettings.Display = Display.Dynamic;
l.Properties.ValidationSettings.ErrorDisplayMode = ErrorDisplayMode.ImageWithText;
}).BindList(Model.facilitieslist).GetHtml();
ViewContext.Writer.WriteLine("<br />");
}
Controller:
[HttpPost]
[Authorize]
public ActionResult ViewReport(ReportInfoViewModel _model)
{
string _parameterList = "";
ReportViewerViewModel _rptObj = new ReportViewerViewModel();
if (_model.plaza_param.ToLower().Equals("y"))
{
string[] _selected = DevExpress.Web.Mvc.ListBoxExtension.GetSelectedValues<string>("lstPlazaParam");
string subParam = "plazaparam=";
subParam += String.Join(",", _selected);
_parameterList = string.Concat(_parameterList, "#", subParam);
_parameterList = string.Concat(_parameterList, "#usrplazaparam=", getSelectedPlazaDisplayValues(_model.facilitieslist, _selected));**//here, _model.facilitieslist is null**
}
return View("AfterView", _rptObj);
}
What I am trying to do is on post back, send the model back to the controller. All primitive types are sent back, except the list types. How do I send back a list model on post? Any help is appreciated.

Answer 1

I was able to create a hidden field in my view serializing the list and storing it in the hidden field.
#using (Html.BeginForm("ViewReport", "Reports", Model, FormMethod.Post, new { target = "_blank" }))
{
string facilitiesListJson = Newtonsoft.Json.JsonConvert.SerializeObject(#Model.facilitieslist);
#Html.Hidden("FacilitiesList", facilitiesListJson);
//other form objects
}
In my controller action, I deserialized the hidden field(Request.Form) and access the list.
string _jsonString = Request.Form["FacilitiesList"];
List<FacilityViewModel> _objList = JsonConvert.DeserializeObject<List<FacilityViewModel>>(_jsonString);