Applying migration '..._RenameColumnAlert_Identifier'. System.NotImplementedException: The method or operation is not implemented

Question

I've spent last couple of days looking here and here and here among others, but these don't clearly apply to my case, where I'm trying to update a database after a successful.

dotnet ef migrations add RenameColumnAlert_Identifier

In Microsoft.AspNetCore.All (2.0.7) MVC application. I'm using MySql.Data.EntityFrameworkCore (6.10.6) and I thoroughly edited the Migration Up and the ApplicationDbContextModelSnapshot files before attempting the database update. But I still get the Exception copied into my question.

Basically I changed 'Identifier' to 'Alert_Identifier' in Alert.cs class and its associated db table and used 'Alert_Identifier' as foreign key for three other classes/tables.

Migration:

protected override void Up(MigrationBuilder migrationBuilder)
        {
            migrationBuilder.DropColumn(
                name: "Identifier",
                table: "Alert");

            migrationBuilder.RenameColumn(
                name: "language",
                table: "Info",
                newName: "Language");

            migrationBuilder.RenameColumn(
                name: "Language",
                table: "Alert",
                newName: "Alert_Identifier");

            migrationBuilder.AddColumn<string>(
                name: "Alert_Identifier",
                table: "Resource",
                nullable: false);

            migrationBuilder.AddColumn<string>(
                name: "Alert_Identifier",
                table: "Info",
                nullable: false);

            migrationBuilder.AddColumn<string>(
                name: "Alert_Identifier",
                table: "Area",
                nullable: false);
        }

Specifically, the Stack Trace starts with: at Microsoft.EntityFrameworkCore.Migrations.MigrationsSqlGenerator.Generate(RenameColumnOperation operation, IModel model, MigrationCommandListBuilder builder)

This seems to indicate that there is something amiss with the RenameColumnoperation. Is this not yet implemented? Is there a workaround? Any help would be greatly appreciated.

I'm stuck with the same problem. Did you find out any solution? — Rafael Osuna Dominguez, Nov 19 '18 at 18:44
Hi @Rafael Osuna Dominguez, sorry I didn't get to this till now. It turned out that RenameColumn() isn't supported, so I had to DropColumn()/AddColumn(() for each column I wanted to rename. — Rex B, Nov 22 '18 at 18:08

score 0 · Answer 1 · answered Oct 16 '21 at 16:33

This still isn't implemented in the MySql.EntityFrameworkCore (5.0.5) however the suggestion to just modify the migration and change RenameColumn to a DropColumn and AddColumn works however you're going to lose data that way of course.

There is an option and that is to use Pomelo's version as it is a bit more feature rich and regularly maintained - Pomelo.EntityFrameworkCore.MySql will come up as a Nuget package, or alternatively here is the Project URL: https://github.com/PomeloFoundation/Pomelo.EntityFrameworkCore.MySql

score 0 · Answer 2 · answered Oct 20 '21 at 10:27

I know this isn't the ideal solution. But while the method is not supported why not switch to raw SQL.

So for example delete this

  migrationBuilder.RenameColumn(
                name: "language",
                table: "Info",
                newName: "Language");

and replace with

    migrationBuilder.Sql(@"ALTER TABLE `Info` 
                            CHANGE COLUMN `language` `Language`;");

This approach has the benefit of avoiding any data loss problems.

Applying migration '..._RenameColumnAlert_Identifier'. System.NotImplementedException: The method or operation is not implemented

2 Answers2