cannot simplicity convert string to system.collection.generi

Question

Problem

error cannot simplicity convert string to system.collection.generic.ienumerable on view of index

Details

I need to display every department and his employees following to it in tree view using jtree i downloaded from nugget in mvc 5 visual studio 2015 . as department parent and children employee

Sales(parent)

michel(children)

divid(children)

my database data as following

SELECT        dbo.Departments.DepartmentName, dbo.Employee.EmployeeName, dbo.Employee.DepartmentID
FROM            dbo.Employee INNER JOIN
                         dbo.Departments ON dbo.Employee.DepartmentID = dbo.Departments.DepartmentID

 

 

and treeviewhelper class has following function for children

public TreeView<T> Children(Func<T, IEnumerable<T>> selector)
       {
           //  if (selector == null) //throw new ArgumentNullException("selector");
           _childrenProperty = selector;
           return this;
       }

 

my employee controller as following

public class EmployeeController : Controller
    {
        // GET: Employee
        HRSystem hr = new HRSystem();
        public ActionResult Index()
        {
            IEnumerable<Employee> catgory1 = hr.Employees.Where(x => !x.DepartmentID.HasValue).ToList();
            return View(catgory1);
        }
    }

 

my error show on view of index as following

 

@model IEnumerable<EmployeeSystem.Employee>
@using System.Web.UI.WebControls
@using EmployeeSystem.Models;

<h2>TreeView</h2>
<link href="~/Content/jsTree/themes/default/style.min.css" rel="stylesheet" />
<div class="form-body">
    <div id="jstree">
        @(Html.TreeView(Model)
                              .EmptyContent("root")
                              .Children(m=>m.EmployeeName)
                              .HtmlAttributes(new { id = "tree" })
                          .ChildrenHtmlAttributes(new { @class = "subItem" })
                              .ItemText(m => m.EmployeeName)
                              .ItemTemplate(
        @<text>
            <a href="@item.EmployeeName" desc="@item.EmployeeName">@item.EmployeeName</a>
        </text>)
        )
    </div>
</div>

public partial class Employee
    {

        [Key]
        public int EmployeeNo { get; set; }
        [StringLength(100)]
        public string EmployeeName { get; set; }
        public int? DepartmentID { get; set; }
        public virtual Department Department { get; set; }

    }

 

Department model

public partial class Department
    {

        public Department()
        {
            Employees = new HashSet<Employee>();
        }

        public int DepartmentID { get; set; }

        [StringLength(50)]
        public string DepartmentName { get; set; }
        public virtual ICollection<Employee> Employees { get; set; }
    }

 

error display on line Children(m=>m.EmployeeName) on view of index

How to solve it