c# - Nested Model returning null in View -

i know question has been asked before struggling find suitable solution. have foreach loop compares values 2 models , decides parent element each belong can see in view (table has expand/close capability) want each group appear under section have been allocated to, when call item.group.groupsectionid returns null every time, when debugging controller populating groupdetail model , sectiondetail model being populated public groupdetail group { get; set; } returning null:

view (sectiontable)

<table class="table table-striped">     <tbody>     <!-- render details of each employee. -->     @foreach (var item in model)     {     <tr>         <td>-</td>         <td>@html.displayfor(model => item.name)</td>     </tr>      if (item.group.groupsectionid != 0 && item.sectionid == item.group.groupsectionid)     {     <tr>         <td colspan="3"><p>@html.displayfor(model => item.group.groupname)</p></td>     </tr>     }     }      </tbody> </table> 

controllers

public actionresult grouptable() {     manager manager = new manager();     var data1 = manager.getallgroups();     var groupdetails = u in data1     select new groupdetail     {         groupid = u.id,                 groupdescription = u.description,                 groupname = u.name,                 groupsectionid = u.sectionid,                 sectionname = u.sectionname     };     return view(groupdetails.tolist()); }  public actionresult sectiontable() {     manager manager = new manager();     var data3 = manager.getallsections();     var sectiondetails = u in data3     select new sectiondetail     {         sectionid = u.id,                 name = u.name,                 description = u.description     };     return view(sectiondetails.tolist()); } 

models

public class sectiondetail {     public int sectionid { get; set; }     public string name { get; set; }     public string description { get; set; }     public groupdetail group { get; set; }  }  public class groupdetail {     public int groupid { get; set; }     public string groupdescription { get; set; }     public string groupname { get; set; }     public int groupsectionid { get; set; }     public string sectionname { get; set; } } 

thanks in advance , if want further info please ask.

you don't assign group property here:

var sectiondetails = u in data3                      select new sectiondetail                                {                                    sectionid = u.id,                                    name = u.name,                                    description = u.description,                                    group = u.group                                };