connect_base/AvaloniaApplication5/ViewModels/AddDisCursViewModel.cs

using System;
using System.Collections.Generic;
using ReactiveUI;
using System.Linq;
using System.Data;
using AvaloniaApplication5.Models; 
using Microsoft.EntityFrameworkCore;
using MsBox.Avalonia;
using MsBox.Avalonia.Enums;
namespace AvaloniaApplication5.ViewModels
{
	public class AddDisCursViewModel : ViewModelBase
    {
		Course? _newcourse;
		public Course? NewCourse { get => _newcourse; set => this.RaiseAndSetIfChanged(ref _newcourse, value); }
		public List<Course> CoursesList => MainWindowViewModel.myConnection.Courses.ToList();

        public AddDisCursViewModel()
		{
            _newcourse = new Course();
		}

        string _message = "";

        public string Message
        {
            get => _message;
            set => this.RaiseAndSetIfChanged(ref _message, value);
        }


      
        public async void AddCourse()
		{
            
			if(string.IsNullOrEmpty(NewCourse.Time) || !IsNumeric(NewCourse.Time))
			{
                await MessageBoxManager.GetMessageBoxStandard("Ñîîáùåíèå", " ïîëå êîëè÷åñòâà ÷àñîâ äîëæíû áûòü òîëüêî öèôðû").ShowAsync();
                return;
            }
            else
            {
               if (NewCourse.Id == 0)
			   {
                 MainWindowViewModel.myConnection.Courses.Add(NewCourse);
               }
               MainWindowViewModel.myConnection.SaveChanges();
               MainWindowViewModel.Instance.PageContent = new AddPage();
            }
			
        }
        private bool IsNumeric(string value)
        {
            return int.TryParse(value, out _); // Èëè double.TryParse, åñëè íóæíî ïîääåðæèâàòü äðîáíûå ÷èñëà
        }
    }
}