添加迁移时出现无法连接到任何指定的 MySQL 主机错误

Question

所以我正在做学校练习，我必须专门使用 Microsoft.EntityFrameworkCore.Tools 版本 6.0.11。但每次我像练习中所说的那样使用 add-migration Initial 命令时，我都会收到此错误（这些都是以该命令开头的控制台行）

PM> add-migration Initial
Build started...
Build succeeded.
The Entity Framework tools version '6.0.11' is older than that of the runtime '7.0.2'. Update the tools for the latest features and bug fixes. See https://aka.ms/AAc1fbw for more information.
MySqlConnector.MySqlException (0x80004005): Unable to connect to any of the specified MySQL hosts.
   at MySqlConnector.Core.ServerSession.OpenTcpSocketAsync(ConnectionSettings cs, ILoadBalancer loadBalancer, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ServerSession.cs:line 1146
   at MySqlConnector.Core.ServerSession.ConnectAsync(ConnectionSettings cs, MySqlConnection connection, Int32 startTickCount, ILoadBalancer loadBalancer, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ServerSession.cs:line 438
   at MySqlConnector.Core.ConnectionPool.ConnectSessionAsync(MySqlConnection connection, String logMessage, Int32 startTickCount, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ConnectionPool.cs:line 403
   at MySqlConnector.Core.ConnectionPool.ConnectSessionAsync(MySqlConnection connection, String logMessage, Int32 startTickCount, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ConnectionPool.cs:line 408
   at MySqlConnector.Core.ConnectionPool.GetSessionAsync(MySqlConnection connection, Int32 startTickCount, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ConnectionPool.cs:line 98
   at MySqlConnector.Core.ConnectionPool.GetSessionAsync(MySqlConnection connection, Int32 startTickCount, Activity activity, IOBehavior ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/Core/ConnectionPool.cs:line 128
   at MySqlConnector.MySqlConnection.CreateSessionAsync(ConnectionPool pool, Int32 startTickCount, Activity activity, Nullable`1 ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/MySqlConnection.cs:line 929
   at MySqlConnector.MySqlConnection.OpenAsync(Nullable`1 ioBehavior, CancellationToken cancellationToken) in /_/src/MySqlConnector/MySqlConnection.cs:line 423
   at MySqlConnector.MySqlConnection.Open() in /_/src/MySqlConnector/MySqlConnection.cs:line 382
   at Microsoft.EntityFrameworkCore.ServerVersion.AutoDetect(String connectionString)
   at EFSamurai.SamuraiContext.OnConfiguring(DbContextOptionsBuilder optionsBuilder) in E:\School\WebServices\EFSamurai\EFSamurai\SamuraiContext.cs:line 14
   at Microsoft.EntityFrameworkCore.DbContext.get_ContextServices()
   at Microsoft.EntityFrameworkCore.DbContext.get_InternalServiceProvider()
   at Microsoft.EntityFrameworkCore.DbContext.Microsoft.EntityFrameworkCore.Infrastructure.IInfrastructure<System.IServiceProvider>.get_Instance()
   at Microsoft.EntityFrameworkCore.Infrastructure.Internal.InfrastructureExtensions.GetService[TService](IInfrastructure`1 accessor)
   at Microsoft.EntityFrameworkCore.Infrastructure.AccessorExtensions.GetService[TService](IInfrastructure`1 accessor)
   at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(Func`1 factory)
   at Microsoft.EntityFrameworkCore.Design.Internal.DbContextOperations.CreateContext(String contextType)
   at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations.AddMigration(String name, String outputDir, String contextType, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType, String namespace)
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigration.<>c__DisplayClass0_0.<.ctor>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0()
   at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)
Unable to connect to any of the specified MySQL hosts.
PM> 

这是使用 Microsoft EntityFrameworkCore 的类

using Microsoft.EntityFrameworkCore;

namespace EFSamurai
{
    public class SamuraiContext : DbContext
    {
        public DbSet<Samurai> Samurais {get; set;}
        public DbSet<Quote> Quotes { get; set;}
        public DbSet<Battle> Battles { get; set;}

        protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder)
        {
            var connectionString = "server = localhost; port = 3310; database = samurai-db; user=databanken; password=databanken";
            optionsBuilder.UseMySql(connectionString, ServerVersion.AutoDetect(connectionString));
        }
    }
}

Answer 1

它已经在输出中说了

Build succeeded

，所以恐怕迁移工作已经完成。顺便说一下，根据 package 的描述，6.0.11 版本应该可以与 .net 7 一起使用。

错误消息要求您将

Microsoft.EntityFrameworkCore.Tools

版本升级到 v 7.x.x 以启用最新功能。