Question

我正在尝试找出一种推荐的方法，该方法用于调用一个类，该类将在ASP.NET Core 2.1应用中启动应用程序时为我的数据库添加种子。

SeedDatabase.cs类不是静态的，因为它依赖于在ConfigureServices中注册的多个存储库，这些存储库是通过构造函数注入的。

我记得您以前在Configure方法中调用种子类的时候，但是我相信他们建议在2.1中调用它的方法是在Program.cs主方法中。但是，如果我这样做，则只有在类为静态的情况下才起作用，在我的情况下，依赖项注入失败。

Answer 1

根据以下内容更改Program.cs：

public static void Main(string[] args) =>
    MainAsync(args).ConfigureAwait(false).GetAwaiter().GetResult();

public static async Task MainAsync(string[] args)
{
    var host = CreateWebHostBuilder(args).Build();
    // do something
    await host.RunAsync().ConfigureAwait(false);
}

public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
    WebHost.CreateDefaultBuilder(args)
        .UseStartup<Startup>();

在// do something部分中，您现在可以访问已构建的主机对象，这也意味着您可以访问服务。您必须在这里使用服务定位器反模式，对于这种特定用例，实际上是可以的。

您可以采取多种方法。您实际上可以在SeedDatabase中注册ConfigureServices类，然后在此处将其退出，但这很不典型。它只会使用一次，因此并不是真正值得在您的服务集合中注册的东西。更好的方法是使该类成为静态类，并更改实际执行工作的方法以将上下文作为参数。然后，您可以执行以下操作：

using (var scope = host.Services.CreateScope())
{
    var context = scope.ServiceProvider.GetRequiredService<YourContext>();
    await SeedDatabase.SeedFoosAsync(context);
}

Answer 2

由于克里斯（Chris）的回答，我得到了回报：)我正在研究有关Pluralsight的示例，而仅仅是学习.NET Core。

这是起作用的

using System;
using Microsoft.AspNetCore;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.DependencyInjection;
using BethanysPieShop.Models;

namespace BethanysPieShop
{
    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<AppDbContext>();

                                        DbInitializer obj = new DbInitializer();
                obj.Seed(context);
                }
                catch (Exception)
                {
                    //we could log this in a real-world situation
                }

                host.Run();
            }
        }

        public static IWebHostBuilder CreateWebHostBuilder(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>();
    }
}

这是我的DbInitializer类

using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace BethanysPieShop.Models
{
    public class DbInitializer
    {
        public void Seed(AppDbContext context)
        {
            if (!context.Pies.Any())
            {
                context.AddRange(
                new Pie { Name = "Apple Pie", Price = 12.95M, ShortDescription = "Our famous apple pies!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/applepie.jpg", IsPieOfTheWeek = true, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/applepiesmall.jpg" },
                new Pie { Name = "Blueberry Cheese Cake", Price = 18.95M, ShortDescription = "You'll love it!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/blueberrycheesecake.jpg", IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/blueberrycheesecakesmall.jpg" },
                new Pie { Name = "Cheese Cake", Price = 18.95M, ShortDescription = "Plain cheese cake. Plain pleasure.", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/cheesecake.jpg", IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/cheesecakesmall.jpg" },
                new Pie { Name = "Cherry Pie", Price = 15.95M, ShortDescription = "A summer classic!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/cherrypie.jpg", IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/cherrypiesmall.jpg" },
                new Pie { Name = "Christmas Apple Pie", Price = 13.95M, ShortDescription = "Happy holidays with this pie!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/christmasapplepie.jpg", IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/christmasapplepiesmall.jpg" },
                new Pie { Name = "Cranberry Pie", Price = 17.95M, ShortDescription = "A Christmas favorite", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/cranberrypie.jpg", IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/cranberrypiesmall.jpg" },
                new Pie { Name = "Peach Pie", Price = 15.95M, ShortDescription = "Sweet as peach", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/peachpie.jpg", IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/peachpiesmall.jpg" },
                new Pie { Name = "Pumpkin Pie", Price = 12.95M, ShortDescription = "Our Halloween favorite", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/pumpkinpie.jpg", IsPieOfTheWeek = true, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/pumpkinpiesmall.jpg" },
                new Pie { Name = "Rhubarb Pie", Price = 15.95M, ShortDescription = "My God, so sweet!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/rhubarbpie.jpg", IsPieOfTheWeek = true, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/rhubarbpiesmall.jpg" },
                new Pie { Name = "Strawberry Pie", Price = 15.95M, ShortDescription = "Our delicious strawberry pie!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/strawberrypie.jpg", IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/strawberrypiesmall.jpg" },
                new Pie { Name = "Strawberry Cheese Cake", Price = 18.95M, ShortDescription = "You'll love it!", LongDescription = "Icing carrot cake jelly-o cheesecake. Sweet roll marzipan marshmallow toffee brownie brownie candy tootsie roll. Chocolate cake gingerbread tootsie roll oat cake pie chocolate bar cookie dragée brownie. Lollipop cotton candy cake bear claw oat cake. Dragée candy canes dessert tart. Marzipan dragée gummies lollipop jujubes chocolate bar candy canes. Icing gingerbread chupa chups cotton candy cookie sweet icing bonbon gummies. Gummies lollipop brownie biscuit danish chocolate cake. Danish powder cookie macaroon chocolate donut tart. Carrot cake dragée croissant lemon drops liquorice lemon drops cookie lollipop toffee. Carrot cake carrot cake liquorice sugar plum topping bonbon pie muffin jujubes. Jelly pastry wafer tart caramels bear claw. Tiramisu tart pie cake danish lemon drops. Brownie cupcake dragée gummies.", ImageUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/strawberrycheesecake.jpg", IsPieOfTheWeek = false, ImageThumbnailUrl = "https://gillcleerenpluralsight.blob.core.windows.net/files/strawberrycheesecakesmall.jpg" }
            );
        }

        context.SaveChanges();
    }
}

}

在ASP.NET Core 2.1的Application Startup上调用非静态类来播种数据库

2 个答案: