FirstAvalonia/AvaloniaExample/ViewModels/MainWindowViewModel.cs

using Avalonia.Controls;
using AvaloniaExample.Models;
using AvaloniaExample.Views;
using Microsoft.EntityFrameworkCore;
using ReactiveUI;
using System;
using System.Linq;
using Tmds.DBus.Protocol;

namespace AvaloniaExample.ViewModels
{
    public class MainWindowViewModel : ViewModelBase
    {
        UserControl uc = new Page1();   
        Page1ViewModel page1VM = new Page1ViewModel();
        public Page1ViewModel Page1VM { get => page1VM; set => page1VM = value; }
        public UserControl UC { get => uc; set => this.RaiseAndSetIfChanged(ref uc, value); }
        public static UsersContext connection = new UsersContext();
        UserProfileViewModel page3VM;
        public UserProfileViewModel Page3VM { get => page3VM; set => page3VM = value; }
        public void LoadPage2()
        {
            Login? curUser = connection.Logins.FirstOrDefault(x => x.Value == Page1VM.Login && x.Password == Page1VM.Password);
            if (curUser == null)
            {
                Page1VM.Message = "Error. Try again";
                Page1VM.Login = "";
                Page1VM.Password = "";
            }
            else
            {
                switch (curUser.Role)
                {
                    case "администратор":
                        UC = new Page2();
                        break;
                    default:
                        Page3VM = new UserProfileViewModel(connection, curUser.Value);
                        UC = new Page3();
                        break;
                }
            }
            var u = connection.UsersInfos.FirstOrDefault();
            var l = connection.Logins.FirstOrDefault();
        }
        public void SaveChanges() => connection.SaveChanges();

    }
}