1.使用以下代码在 Models 文件夹中创建一个名为 SeedData 的新类：

using Microsoft.EntityFrameworkCore;

using Microsoft.Extensions.DependencyInjection;

using System;

using System.Linq;

namespace RazorPagesMovie.Models

{

public static class SeedData

{

public static void Initialize(IServiceProvider serviceProvider)

{

using (var context = new RazorPagesMovieContext(

serviceProvider.GetRequiredService<

DbContextOptions<RazorPagesMovieContext>>()))

{

// Look for any movies.

if (context.Movie.Any())

{

return; // DB has been seeded

}

context.Movie.AddRange(

new Movie

{

Title = "When Harry Met Sally",

ReleaseDate = DateTime.Parse("1989-2-12"),

Genre = "Romantic Comedy",

Price = 7.99M

},

new Movie

{

Title = "Ghostbusters ",

ReleaseDate = DateTime.Parse("1984-3-13"),

Genre = "Comedy",

Price = 8.99M

},

new Movie

{

Title = "Ghostbusters 2",

ReleaseDate = DateTime.Parse("1986-2-23"),

Genre = "Comedy",

Price = 9.99M

},

new Movie

{

Title = "Rio Bravo",

ReleaseDate = DateTime.Parse("1959-4-15"),

Genre = "Western",

Price = 3.99M

}

);

context.SaveChanges();

}

}

}

}

2.添加种子初始值设定项

在 Program.cs 中，修改 Main 方法以执行以下操作：

从依赖关系注入容器获取数据库上下文实例。

调用 seed 方法，并将上下文传递给它。

Seed 方法完成时释放上下文。

下面的代码显示更新后的 Program.cs 文件。

using Microsoft.AspNetCore;

using Microsoft.AspNetCore.Hosting;

using Microsoft.Extensions.DependencyInjection;

using Microsoft.Extensions.Logging;

using RazorPagesMovie.Models;

using System;

using Microsoft.EntityFrameworkCore;

namespace RazorPagesMovie

{

public class Program

{

public static void Main(string[] args)

{

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

using (var scope = host.Services.CreateScope())

{

var services = scope.ServiceProvider;

try

{

var context=services.

GetRequiredService<RazorPagesMovieContext>();

context.Database.Migrate();

SeedData.Initialize(services);

}

catch (Exception ex)

{

var logger = services.GetRequiredService<ILogger<Program>>();

logger.LogError(ex, "An error occurred seeding the DB.");

}

}

host.Run();

}

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>

WebHost.CreateDefaultBuilder(args)

.UseStartup<Startup>();

}

}