Update-Database 命令在 ASP.Net Core/Entity Framework Core 中不起作用，因为数据库中的对象已经存在 [英] Update-Database command is not working in ASP.Net Core / Entity Framework Core because object in database already exists

问题描述

我正在通过命令行更新我的数据库，但后来我手动更新了我的一个表.

I was updating my database by the command line, but then I manually updated one of my tables.

这似乎破坏了我更新数据库的能力.当我尝试更新时收到以下错误:

This seems to have disrupted my ability to update-database. I receive the following error when I try to update:

 System.Data.SqlClient.SqlException: There is already an object named 'ClientsAndTestimonials' in the database.    at System.Data.SqlClient.SqlConnection.OnError(SqlException exception, Boolean breakConnection, Action`1 wrapCloseInAction)
   at System.Data.SqlClient.TdsParser.ThrowExceptionAndWarning(TdsParserStateObject stateObj, Boolean callerHasConnectionLock, Boolean asyncClose)
    at System.Data.SqlClient.TdsParser.TryRun(RunBehavior runBehavior, SqlCommand cmdHandler, SqlDataReader dataStream, BulkCopySimpleResultSet bulkCopyHandler, TdsParserStateObject stateObj, Boolean& dataReady)
   at System.Data.SqlClient.SqlCommand.RunExecuteNonQueryTds(String methodName, Boolean async, Int32 timeout, Boolean asyncWrite)
    at System.Data.SqlClient.SqlCommand.InternalExecuteNonQuery(TaskCompletionSource`1 completion, Boolean sendToPipe, Int32 timeout, Boolean asyncWrite, String methodName)
    at System.Data.SqlClient.SqlCommand.ExecuteNonQuery()
    at Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.Execute(IRelationalConnection connection, String executeMethod, IReadOnlyDictionary`2 parameterValues, Boolean openConnection, Boolean closeConnection) 
    at Microsoft.EntityFrameworkCore.Storage.Internal.RelationalCommand.ExecuteNonQuery(IRelationalConnection connection, IReadOnlyDictionary`2 parameterValues, Boolean manageConnection) 
    at Microsoft.EntityFrameworkCore.Migrations.Internal.MigrationCommandExecutor.ExecuteNonQuery(IEnumerable`1 migrationCommands, IRelationalConnection connection) 
    at Microsoft.EntityFrameworkCore.Migrations.Internal.Migrator.Migrate(String targetMigration) 
    at Microsoft.EntityFrameworkCore.Design.MigrationsOperations.UpdateDatabase(String targetMigration, String contextType) 
    at Microsoft.EntityFrameworkCore.Tools.Cli.DatabaseUpdateCommand.<>c__DisplayClass0_0.<Configure>b__0() 
    at Microsoft.Extensions.CommandLineUtils.CommandLineApplication.Execute(String[] args)
    at Microsoft.EntityFrameworkCore.Tools.Cli.Program.Main(String[] args)
 ClientConnectionId:d89989a8-ce8b-4167-be7e-fcddc4bcdf98
 Error Number:2714,State:6,Class:16
 There is already an object named 'ClientsAndTestimonials' in the database. 

过去几天我一直在努力解决这个问题.大多数开发人员建议使用 Add-migration "Reset" -IgnoreChanges 的一些变体，例如 John Salewski 来自以下 链接.

I have been trying to fix this problem for the past few days. Most fellow developers suggest some variation of using Add-migration "Reset" -IgnoreChanges, like John Salewski from the following link.

但是，我不断收到错误消息，提示找不到与参数名称‘IgnoreChanges’匹配的参数".

However, I keep getting an error that says "A parameter cannot be found that matches parameter name 'IgnoreChanges'".

任何建议将不胜感激！

推荐答案

EF Core 当前没有 -IgnoreChanges(参见 此处) 但您可以通过注释掉 Up() 方法中的所有代码并应用迁移来实现等效效果.这将拍摄当前模型状态的快照，以便后续迁移仅包括从该点开始的更改.

There is no -IgnoreChanges currently in EF Core (see here) but you can achieve the equivalent by commenting out all the code in the Up() method and applying the migration. This will take a snapshot of the current model state so that subsequent migrations will only include changes from that point forward.

因此，如果您只是进行了一些增量模型更改，而您没有此初始基线，则可能需要删除这些更改，应用基线迁移，然后将更改添加回去并添加第二次迁移.

So if you just made some incremental model change and you don't have this initial baseline you may need to remove those changes, apply the baseline migration, then add your changes back and add a 2nd migration.

这篇关于Update-Database 命令在 ASP.Net Core/Entity Framework Core 中不起作用，因为数据库中的对象已经存在的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！