ASP - Core 在启动时迁移 EF Core SQL 数据库

Question

是否可以让我的 ASP Core Web API 确保将数据库迁移到使用 EF Core 的最新迁移？我知道这可以通过命令行完成，但我想以编程方式完成。

Answer 1

您可以使用

db.Database.EnsureCreated();

让您的数据库与您当前的模型保持同步。如果要启用迁移（如果怀疑后续迁移），则使用

db.Database.Migrate();

并随着时间的推移进行后续迁移。

Answer 2

文档中关于调用 db.Database.EnsureCreated() 的注释：

Note that this API does not use migrations to create the database. In addition, the database that is created cannot be later updated using migrations. If you are targeting a relational database and using migrations, you can use the DbContext.Database.Migrate() method to ensure the database is created and all migrations are applied.

您可能只想致电 db.Database.Migrate()。

从声明上方找到的来源中获取的评论 here。

Answer 3

根据@steamrolla 的回答，我提出以下改进建议：

public static class EnsureMigration
{
    public static void EnsureMigrationOfContext<T>(this IApplicationBuilder app) where T:DbContext
    {
        var context = app.ApplicationServices.GetService<T>();
        context.Database.Migrate();
    }
}

有了这个你也可以保证不同上下文的迁移，例如如果您有身份数据库。

用法：

app.EnsureMigrationOfContext<context>();

Answer 4

使用下面的代码运行在

迁移

public async void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    using (var serviceScope = app.ApplicationServices.GetRequiredService<IServiceScopeFactory>().CreateScope())
    {
        var context = serviceScope.ServiceProvider.GetService<YourContext`enter code here`>();
        context.Database.Migrate();
    }
}

Answer 5

根据chintan310的回答，我是这样迁移数据库的。这确保将与数据库相关的任务分离到 Program.cs:

    public static void Main(string[] args)
    {
        var host = BuildWebHost(args);

        using (var scope = host.Services.CreateScope())
        {
            var services = scope.ServiceProvider;

            try
            {
                var context = services.GetService<AppDbContext>();
                context.Database.Migrate();

                var seeder = scope.ServiceProvider.GetService<AppSeeder>();
                seeder.Seed().Wait();
            }
            catch (Exception ex)
            {
                var logger = services.GetRequiredService<ILogger<Program>>();
                logger.LogError(ex, "An error occurred seeding the DB.");
            }
        }

        host.Run();
    }

    private static IWebHost BuildWebHost(string[] args) =>
        WebHost.CreateDefaultBuilder(args)
            .UseStartup<Startup>()
            .Build();

Answer 6

我这样做是为了通过 EF Core 2.1.2 和 SQL 服务器以编程方式迁移，基于此处的先前答案和 bailando bailando's answer on "How and where to call Database.EnsureCreated and Database.Migrate?":

Startup.cs

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.EntityFrameworkCore;

namespace MyApp
{
    public class Startup
    {
        // ... (only relevant code included) ...

        public void ConfigureServices(IServiceCollection services)
        {
            services.AddDbContext<MyAppContext>(options => 
                options.UseSqlServer(Configuration.GetConnectionString("MyAppContext")));
            // ...
        }

        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            using (var serviceScope = app.ApplicationServices.CreateScope())
            {
                var context = serviceScope.ServiceProvider.GetService<MyAppContext>();
                context.Database.Migrate();
            }
            // ...
        }
    }
}

使用此代码的项目是available at Github。

Answer 7

这是对先前创建扩展方法的答案的轻微修正。它修复了按照编写方式抛出的错误。

using System;
using System.Collections.Generic;
using System.Text;
using Microsoft.AspNetCore.Builder;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.DependencyInjection;

namespace MyApp.Extensions
{
    public static class IApplicationBuilderExtensions
    {
        public static void SyncMigrations<T>(this IApplicationBuilder app) where T : DbContext
        {
            using (var serviceScope = app.ApplicationServices.GetRequiredService<IServiceScopeFactory>().CreateScope())
            {
                var context = serviceScope.ServiceProvider.GetService<T>();
                context.Database.Migrate();
            }
        }
    }
}

Answer 8

此代码适用于 .NET core 3.0

 using (var scope = app.ApplicationServices.CreateScope())
 {
     var dbContext = scope.ServiceProvider.GetService<T>();
     dbContext.Database.Migrate();
 }

Answer 9

这在 ASP.NET Core 3.1 中对我有用，在 ConfigureServices 方法中注册后，只需将数据库上下文作为参数注入现有 Configure 方法。

public void ConfigureServices(IServiceCollection services)
{
    services.AddDbContext<DataContext>(x => x.UseSqlite("Data Source=LocalDatabase.db"));

    ...
}

public void Configure(IApplicationBuilder app, IWebHostEnvironment env, DataContext dataContext)
{
    dataContext.Database.Migrate();

    ...
}

更多详细信息和完整代码示例的链接可在 https://jasonwatmore.com/post/2019/12/27/aspnet-core-automatic-ef-core-migrations-to-sql-database-on-startup

Answer 10

我遵循了 IStartupFilter 方法来获得迁移任何上下文的通用方法。

 public class DataContextAutomaticMigrationStartupFilter<T> : IStartupFilter
  where T : DbContext
{
    /// <inheritdoc />
    public Action<IApplicationBuilder> Configure(Action<IApplicationBuilder> next)
    {
        return app =>
        {
            using (var scope = app.ApplicationServices.CreateScope())
            {
                scope.ServiceProvider.GetRequiredService<T>().Database.SetCommandTimeout(160);
                scope.ServiceProvider.GetRequiredService<T>().Database.Migrate();
            }
            next(app);
        };
    }
}

现在我们可以通过以下方式注册 DataContext 和迁移：

第一个上下文

 services.AddDbContext<ConsumerDataContext>(options => options.UseSqlServer(configuration.GetConnectionString("ConsumerConnection")), ServiceLifetime.Transient);
    services.AddTransient<IStartupFilter, DataContextAutomaticMigrationStartupFilter<ConsumerDataContext>>();

第二个上下文

services.AddDbContext<UserDataContext>(options => options.UseSqlServer(configuration.GetConnectionString("UserConnection")), ServiceLifetime.Transient);
services.AddTransient<IStartupFilter, DataContextAutomaticMigrationStartupFilter<UserDataContext>>();

..等等..

IStartupFilter的罪魁祸首是它只允许同步执行代码。对于数据库迁移，这不是问题，因为我们有同步 Migrate() 方法。

Answer 11

使用 C# 7.1 启动 .NET Core 2，您可以对您的应用程序使用异步 Main 方法，这样您就可以在运行主机之前调用所有初始化逻辑，就在它具有完成建筑：

public class Program
{
  public static async Task Main(string[] args)
  {
    //first build
    var host = CreateHostBuilder(args).Build();

    //initialize
    using (var serviceScope = host.Services.CreateScope())
    {
      var serviceProvider = serviceScope.ServiceProvider;
      var isDevelopment = 
        serviceProvider.GetRequiredService<IWebHostEnvironment>().IsDevelopment();

      using var context = serviceProvider.GetRequiredService<AppDbContext>();


      if (isDevelopment)
        await context.Database.EnsureCreatedAsync();
      else
        await context.Database.MigrateAsync();

      if (isDevelopment)
      {
        using var userManager = 
          serviceProvider.GetRequiredService<UserManager<AppUser>>();
        await userManager
          .CreateAsync(new AppUser { UserName = "dummy", Email = "dummy@dumail.com" },
          password: "1234");
      }
    }

    //now run
    host.Run();
  }

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

Answer 12

在 Asp core 6 中你没有 StartUp ，在以前的 asp 版本中我们有 Configure 方法允许直接访问 ServiceProvider 然后我们可以使用 GetServices 获取 DBcontext 然后调用迁移方法。

但现在 Asp 核心 6。我们应该创建一个范围然后获取 DBcontext 对象

        using (var Scope = app.services.CreateScope())
        {
            var context = Scope.Services.GetRequireService<DBContext>();
            context.Database.Migrate();
        }

ASP - Core 在启动时迁移 EF Core SQL 数据库

ASP - Core Migrate EF Core SQL DB on Startup

c#

entity-framework-core

asp.net-core