Form1.cs

using Microsoft.AspNetCore.Components.WebView.WindowsForms;
using Microsoft.Extensions.DependencyInjection;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using BlazorWinForms.Data;

namespace BlazorWinForms
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            var services = new ServiceCollection();
            services.AddWindowsFormsBlazorWebView();
            services.AddSingleton<WeatherForecastService>();
            blazorWebView1.HostPage = "wwwroot\\index.html";
            blazorWebView1.Services = services.BuildServiceProvider();
            blazorWebView1.RootComponents.Add<Main>("#app");
        }

    }
}