Object reference is required for non-static field, method or property

Question

working on a login method, using Mdi, and MVC. The Class structure is very elaborate, so constant references between classes is required. However, when I try to change the Main Menu view, I get the "object reference is required for non-static field, method or property".

I am still only an amateur, started 2 months ago and self-taught, so I am still fuzzy on what the error is actually referring to and what it means.

Here is the Menu View Class:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using DCIM_With_Test.User;

namespace DCIM_With_Test.Menu
{
     public partial class Menu_View : Form
     {
         public static int btnUser;

        public Menu_View()
        {
            InitializeComponent();  //runs the Main Menu form
             User_Controller CreateLoginView = new User_Controller(); //opens the Show_Login method in the User_Controller
            CreateLoginView.Show_Login(this); //sets the Mdi Parent container
        }

        public void SetMenuView()
        {
            switch (Db_Facade.ACCESS)
            {
                case 1:
                     plantAreaCodeToolStripMenuItem.Visible = true;
                     cableIDToolStripMenuItem.Visible = true;
                     logOutToolStripMenuItem.Visible = true;
                     createNewUserToolStripMenuItem.Visible = true;
                     editUserToolStripMenuItem.Visible = true;
                     break;
                 default:
                    plantAreaCodeToolStripMenuItem.Visible = false;
                    cableIDToolStripMenuItem.Visible = false;
                    logOutToolStripMenuItem.Visible = false;
                    createNewUserToolStripMenuItem.Visible = false;
                    editUserToolStripMenuItem.Visible = false;
                    break;
            }
        }

The User Controller:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using DCIM_With_Test.Menu;

namespace DCIM_With_Test.User
{
    class User_Controller
    {
        public void Show_Login(Menu_View Main_Menu)
        {
            User_Login_View LoginView = new User_Login_View(); // Creates an object of the User_Login_View.
            LoginView.MdiParent = Main_Menu; // Set the Parent Form of the Child window.
            LoginView.Show(); // Display the new form.
        }

        public void Show_User(Menu_View Main_Menu)
        {
            User_Edit_View EditUserView = new User_Edit_View(); // Creates an objet of the User_View.
            EditUserView.MdiParent = Main_Menu; // Set the Parent Form of the Child window.
            EditUserView.Show(); // Display the new form.
        }

        public static void Compare_Login(User_Login_View Login_View)
        {
            User_Model getACCESS = new User_Model();
            getACCESS.uName = Login_View.txtUsername.Text;
            getACCESS.uPwd = Login_View.txtPassword.Text;

            Db_Facade.ACCESS = 1;

            if (Db_Facade.ACCESS > 0)
            {
                Login_View.Close();
            }
            else
            {
                Login_View.lblError.Visible = true;
            }

            Menu_View.SetMenuView(); //here is where the error occurs
        }
    }
}

The Db_Facade Class is currently just a collection of Variables, hence why ACCESS is set to 1 in the User_Controller

Answer 1

Your problem occurs because you don't have a reference to the Menu_View object inside your function, so it tries to reference the Menu_View class, which doesn't have any static members assigned. It looks like what you want to do is call Login_View.MdiParent.SetMenuView()

EDIT

You probably need to cast your call, as you are saving Main_Menu into LoginView.MdiParent which stores it as it's base class Form. Try: (Main_Menu)Login_View.MdiParent.SetMenuView()

If casting the object isn't possible, then what you can do is create a Property to access the object directly.

In your User_Login_View, create a new property public Menu_View Menu {get;set;}. Then, in your Show_Login function, add a line to set the Menu object LoginView Menu = Main_Menu;. Now, you can reference LoginView.Menu.SetMenuView(); without needing a cast.