当我在VS2015中使用ASP运行PM> Remove-Migration -context BloggingContext时。NET Core项目使用EF Core我得到以下错误:

System.InvalidOperationException: The migration '20160703192724_MyFirstMigration' has already been applied to the database. Unapply it and try again. If the migration has been applied to other databases, consider reverting its changes using a new migration.    at Microsoft.EntityFrameworkCore.Migrations.Design.MigrationsScaffolder.RemoveMigration(String projectDir, String rootNamespace, Boolean force) 
    at Microsoft.EntityFrameworkCore.Design.MigrationsOperations.RemoveMigration(String contextType, Boolean force) 
    at Microsoft.EntityFrameworkCore.Tools.Cli.MigrationsRemoveCommand.<>c__DisplayClass0_0.<Configure>b__0() 
    at Microsoft.Extensions.CommandLineUtils.CommandLineApplication.Execute(String[] args) 
    at Microsoft.EntityFrameworkCore.Tools.Cli.Program.Main(String[] args) 
 The migration '20160703192724_MyFirstMigration' has already been applied to the database. Unapply it and try again. If the migration has been applied to other databases, consider reverting its changes using a new migration.

如何取消申请?我使用的是ASP的最新版本。NET Core 1.0, EF Core和VS2015更新3。


当前回答

dotnet ef database update <the-migration-you-want-to-recover>
dotnet ef migrations remove

不要忘记remove- call,因为这将为您删除迁移文件并更新快照文件。

其他回答

要恢复所有应用到DB的迁移,只需运行:

update-database 0

在migration目录中有可见的迁移文件时,应该多次运行Remove-Migration。该命令删除最近一次迁移,同时更新快照。

在包管理器控制台:

- database就Your_Migration_You_Want_To_Revert_To

关于如何恢复迁移的更多选项和解释可以在这里看到

在迁移已经应用到数据库后“取消”最近的迁移:

Open the SQL Server Object Explorer (View -> "SQL Server Object Explorer") Navigate to the database that is linked to your project by expanding the small triangles to the side. Expand "Tables" Find the table named "dbo._EFMigrationsHistory". Right click on it and select "View Data" to see the table entries in Visual Studio. Delete the row corresponding to your migration that you want to unapply (Say "yes" to the warning, if prompted). Run "dotnet ef migrations remove" again in the command window in the directory that has the project.json file. Alternatively, run "Remove-Migration" command in the package manager console.

希望这有助于并适用于项目中的任何迁移…我只测试了最近的迁移…

编码快乐!

dotnet ef database update <the-migration-you-want-to-recover>
dotnet ef migrations remove

不要忘记remove- call,因为这将为您删除迁移文件并更新快照文件。

因为这个问题本身涉及到第一次迁移,所以这个答案适用于任何正在寻找恢复上次迁移的方法的人,因为大多数答案不包括替代场景(对我们大多数人来说,这不是我们的第一次迁移,我们不能抹掉整个迁移历史)。这些命令用于包管理器控制台。

假设你的代码中有以下迁移:

20220110 _initialmigration 20200210 _goodmigration 20200210 _lastgoodmigration 20200210 _badmigration 20200210 _badmigrationagain

如果您已经像问题中那样将迁移应用到db

运行: Update-Database -Migration <Last_Good_Migration_Name> 注:名称不能有日期前缀。例如:Update-Database -Migration LastGoodMigration 然后删除坏迁移运行: Remove-Migration 注意:因为我们有两次糟糕的迁移,所以运行两次Remove Migration命令。

如果您还没有将迁移应用到db

运行:

Remove-Migration

在本例中,运行两次Remove Migration命令。

希望这能帮助到一些人。