Asp.Net Core EF Migrations（二）

　　asp.net core 中实现DBContext的初始化，先创建一个ApplicationDBContextSeed，作为初始化基础数据的类，

需要引用 using Microsoft.Extensions.DependencyInjection 和 using Microsoft.Extensions.Logging ，只有在初始化创建数据库的时候将默认的admin账号写入表中

 public class ApplicationDBContextSeed
    {
        private UserManager<ApplicationUser> _userManager;
        public  async Task SeedAsync(ApplicationDBContext contest,IServiceProvider serviceProvider)
        {
            if (!contest.Users.Any())
            {
                _userManager = serviceProvider.GetRequiredService<UserManager<ApplicationUser>>();

                var defultUser = new ApplicationUser
                {
                    UserName = "admin",
                    Email = "leo@qq.com",
                    NormalizedUserName = "admin"
                };
                var  resilt= await _userManager.CreateAsync(defultUser, "123456");
                if(!resilt.Succeeded)
                {
                    throw new Exception("初始化用户信息失败!");
                }
            }
        }
    }

创建WebHostMirgationExtensions

 public static class WebHostMirgationExtensions
    {
        public  static IWebHost  MigrateDbContext<TContext>(this IWebHost host,Action<TContext,IServiceProvider> sedder) where TContext:DbContext
        {
            using (var scope =host.Services.CreateScope())
            {
                var services = scope.ServiceProvider;
                var logger = services.GetRequiredService<ILogger<TContext>>();
                var context = services.GetService<TContext>();
                try
                {
                    context.Database.Migrate();//每次执行都会自动去更新数据库
                    sedder(context, services);
                    logger.LogInformation($"执行DBContext:{typeof(TContext).Name} seed方法成功");
                }
                catch (Exception ex)
                {
                    logger.LogError(ex, $"执行DBContext:{typeof(TContext).Name} seed方法失败");
                }
            }
           
            return host;
        }
    }

修改Program

　　

 public static void Main(string[] args)
        {
            BuildWebHost(args)
                .MigrateDbContext<ApplicationDBContext>((context, server) => {
                    new ApplicationDBContextSeed().SeedAsync(context, server).Wait(); }
                ).Run();
        }