播种身份角色

Question

我已关注this article，了解如何将角色播种到数据库。它通过在Program.cs 中创建的范围内调用播种方法来创建角色，如下所示：

public class Program
{
    public static void Main(string[] args)
    {
        using (var scope = host.Services.CreateScope())
        {
            var services = scope.ServiceProvider;
            try
            {
                var serviceProvider = services.GetRequiredService<IServiceProvider>();
                var configuration = services.GetRequiredService<IConfiguration>();
                Seed.CreateRoles(serviceProvider, configuration).Wait();

            }
            catch (Exception exception)
            {
                var logger = services.GetRequiredService<ILogger<Program>>();
                logger.LogError(exception, "An error occurred while creating roles");
            }
        }

        CreateHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            });
}

但是，在这一行：using (var scope = host.Services.CreateScope())，我在“主机”上得到一个红色波浪线：“名称'主机'在当前上下文中不存在”。如何让它在 Asp.Net Core 3.1 中工作？

这是播种方法：

public static class Seed
{
    public static async Task CreateRoles(IServiceProvider serviceProvider, IConfiguration Configuration)
    {
        //adding customs roles
        var RoleManager = serviceProvider.GetRequiredService<RoleManager<IdentityRole>>();
        var UserManager = serviceProvider.GetRequiredService<UserManager<ApplicationUser>>();
        string[] roleNames = { "Admin", "HRManager", "User" };
        IdentityResult roleResult;

        foreach (var roleName in roleNames)
        {
            // creating the roles and seeding them to the database
            var roleExist = await RoleManager.RoleExistsAsync(roleName);
            if (!roleExist)
            {
                roleResult = await RoleManager.CreateAsync(new IdentityRole(roleName));
            }
        }

        // creating a super user who could maintain the web app
        var poweruser = new ApplicationUser
        {
            UserName = Configuration.GetSection("AppSettings")["UserEmail"],
            Email = Configuration.GetSection("AppSettings")["UserEmail"]
        };

        string userPassword = Configuration.GetSection("AppSettings")["UserPassword"];
        var user = await UserManager.FindByEmailAsync(Configuration.GetSection("AppSettings")["UserEmail"]);

        if (user == null)
        {
            var createPowerUser = await UserManager.CreateAsync(poweruser, userPassword);
            if (createPowerUser.Succeeded)
            {
                // here we assign the new user the "Admin" role 
                await UserManager.AddToRoleAsync(poweruser, "SiteAdmin");
            }
        }
    }
}

Answer 1

首先，我不知何故错过了这一行：

var host = BuildWebHost(args);

但这无论如何都没有用。我不得不用这个替换它：

var host = CreateHostBuilder(args).Build();

所以现在，Program.cs 看起来像这样：

public class Program
{
    public static void Main(string[] args)
    {
        var host = CreateHostBuilder(args).Build();
        using (var scope = host.Services.CreateScope())
        {
            var services = scope.ServiceProvider;
            try
            {
                var serviceProvider = services.GetRequiredService<IServiceProvider>();
                var configuration = services.GetRequiredService<IConfiguration>();
                Seed.CreateRoles(serviceProvider, configuration).Wait();

            }
            catch (Exception exception)
            {
                var logger = services.GetRequiredService<ILogger<Program>>();
                logger.LogError(exception, "An error occurred while creating roles");
            }
        }

        CreateHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseStartup<Startup>();
            });
}

而且它有效！ :) 角色被写入数据库。