ASP .NET Core+Angular5数据库迁移异常解决方法

女爷i 2022-06-02 11:26 88阅读 0赞

今天在完成ASP .NET Core+Angular5项目的时候，更新了Model，把原有的数据库删除了，之后进行数据库迁移时一直发生异常，提示如下：

Entity Framework Core 2.0.1-rtm-125 initialized 'ApplicationDbContext' using provider 'Microsoft.EntityFrameworkCore.SqlServer' with options: None

和

An error occurred while calling method 'BuildWebHost' on class 'Program'. Continuing without the application service provider. Error: Cannot open database "DB\_OnlineShoppingSystem" requested by the login. The login failed. Login failed for user

最后解决方法如下:

1、打开`Startup.cs`文件并删除（或注释掉）以下行：

// Create a service scope to get an ApplicationDbContext instance using DI
        using (var serviceScope =
        app.ApplicationServices.GetRequiredService<IServiceScopeFactory>().CreateScope())
        {
            var dbContext = serviceScope.ServiceProvider.GetService<ApplicationDbContext>();
            // Create the Db if it doesn't exist and applies any pending migration.
            dbContext.Database.Migrate();
            // Seed the Db.
            DbSeeder.Seed(dbContext);
        }

2、 打开 `Program.cs` 并替换此代码：

public static void Main(string[] args)
        {
            BuildWebHost(args).Run();
        }

与此代码：

using Microsoft.Extensions.DependencyInjection;

public static void Main(string[] args)
        {
            var host = BuildWebHost(args);
            using (var scope = host.Services.CreateScope())
            {
                var dbContext = scope.ServiceProvider.GetService<ApplicationDbContext>();
                DbSeeder.Seed(dbContext);
            }
            host.Run();
        }

3、打开命令提示符并浏览项目的根目录

4、键入以下命令：

dotnet ef migrations add "Initial" -o "Data\Migrations"

dotnet ef database update

附上解决方法链接:https://github.com/PacktPublishing/ASP.NET-Core-2-and-Angular-5/issues/4