Get an object attribute of a model in a View

Question

I've created a class called Employee. An Employee has a IManager object as a property like this:

public class Employee : IManagable{
(...)
public IManager ManagedBy
        {get; set;}
(...)
}

This is my Manager class that implements the IManager interface

    public class Manager : IManager, IManagable
    {
(...)
        public string FirstName
        {get; set}
       

        public string LastName
        {get; set}
(...)
    }

Now I want to list a bunch of information with the help of the View code below.

@model IEnumerable<LibraryApplication.Models.Domain.Employee.Employee>

<p>
    @Html.ActionLink("Create New", "Create")
</p>
<table class="table">
    <tr>
        <th>
            @Html.DisplayNameFor(model => model.FirstName)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.LastName)
        </th>
        <th>
            @Html.DisplayNameFor(model => model.Salary)
        </th>
        <td>
            @Html.DisplayNameFor(model => model.ManagedBy)
        </td>
        <th></th>
    </tr>

    @foreach (var item in Model)
    {
        <tr>
            <td>
                @Html.DisplayFor(modelItem => item.FirstName)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.LastName)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.Salary)
            </td>
            <td>
                @Html.DisplayFor(modelItem => item.ManagedBy)
            </td>
            <td>
                @Html.ActionLink("Edit", "Edit", new { id = item.Id }) |
                @Html.ActionLink("Delete", "Delete", new { id = item.Id })
            </td>
        </tr>
    }

</table>

If I want to access an attribute of the manager, what can I do? I've tried this: @Html.DisplayFor(modelItem => item.ManagedBy.FirstName) to add the first name of the manager in the table but it throws this error

System.ArgumentException: 'The property LibraryApplication.Models.Domain.Employee.IManager.FirstName could not be found

When i just do this @Html.DisplayFor(modelItem => item.ManagedBy) it lists all the properties for the manager like below, which is not relevant in this case.

what can i do?

The IManager interface is this simple interface:

    public interface IManager : IEmployee
    {
    }

(it will declare other methods in the future)

and this is my IEmployee interface:

namespace LibraryApplication.Models.Domain.Employee
{
    public interface IEmployee
    {
        int Id
        {
            get;
            set;
        }

        string FirstName
        {
            get;
            set;
        }

        string LastName
        {
            get;
            set;
        }

        double Salary
        {
            get;
            set;
        }

        bool IsCEO
        {
            get;
        }

        bool IsManager
        {
            get;
        }

    }
}

As you can see, the Manager has a FirstName property so I can easily reference it. But why can't i do it in my View file?

EDIT
Now I can make it work in 2 different ways. Either I change the ManagedBy property to Manager instead of IManager . OR i add the following to my IManager interface:

public IManager ManagedBy
        {get; set;}

It works both ways. But why do i have to declare ManagedBy in IManager as well if I already declare it in the IEmployee interface that IManager implements?

Answer 1

you should use manager mangedby instead of Imanager

public class Employee : IManagable{
(...)
public Manager ManagedBy
        {get; set;}
(...)
}

Answer 2

you have to review your logic:

  manager is also an employee, so you could derive Manager from IEmployee

  you specify in Interface IManager, what is just needed for managers