avaloniaProject/AvaloniaApplication5/ViewModels/MainWindowViewModel.cs

using Avalonia.Controls;
using AvaloniaApplication5.Models;
//using AvaloniaApplication5.Models;
using AvaloniaApplication5.Views;
using Microsoft.EntityFrameworkCore;
using ReactiveUI;
using System.Collections.Generic;
using System.Linq;
using Tmds.DBus.Protocol;

namespace AvaloniaApplication5.ViewModels
{
    public class MainWindowViewModel : ViewModelBase
    {
       static  _1234Context DBConnect = new _1234Context();

        private UserControl uc = new PageLogin();
        public UserControl UC { get => uc; set => this.RaiseAndSetIfChanged(ref uc, value); }


        #region VMLogin

        PageLoginViewModel pageLoginVM = new PageLoginViewModel();
        public PageLoginViewModel PageLoginVM { get => pageLoginVM; set => pageLoginVM = value; }
        public void LoadPageList()
        {
            Logintable? currentUser = DBConnect.Logintables.FirstOrDefault(x => x.Login == PageLoginVM.Login && x.Password == PageLoginVM.Password);
            if (currentUser != null)
            {
                switch (currentUser.IdRole)
                {
                    case 1:
                        UC = new PageUserList();
                        break;
                    case 2:
                        PageUCabinetVM = new PageUserCabinetViewModel(DBConnect, currentUser.Id);
                        UC = new PageUserCabinet();
                        break;
                }
            }
            else PageLoginVM.Message = "Пользователь отсутствует в системе, либо указанные данные введены неверно";
        }
        #endregion

        #region VMUserCabinet

        private PageUserCabinetViewModel pageUCabinetVM;
        public PageUserCabinetViewModel PageUCabinetVM { get => pageUCabinetVM; set => pageUCabinetVM = value; }
        #endregion



        #region VMadmin
        private PageUserListViewModel pageUserListViewVM = new PageUserListViewModel(DBConnect);
        public PageUserListViewModel PageUserListViewVM { get => pageUserListViewVM; set => pageUserListViewVM = value; }

        UserControl ucAdmin;
        public UserControl UCAdmin
        {
            get => ucAdmin;
            set => this.RaiseAndSetIfChanged(ref ucAdmin, value);
        }

        public void EditUser(int id)
        {
            PageUCabinetVM = id == 0 ? new PageUserCabinetViewModel(DBConnect) : new PageUserCabinetViewModel(DBConnect, id);
            UCAdmin = new PageUserCabinet();
        }

        public void DeleteUser(int id)
        {
            Logintable? delUser = DBConnect.Logintables.FirstOrDefault(x => x.Id == id);
            DBConnect.Logintables.Remove(delUser);
            DBConnect.SaveChanges();
            UC = new PageUserList();//для обновления списка на странице
        }
        #endregion


    }
}