Entity Framework Core Enable-Migrations 构建带有错误的 Configuration.cs 文件

Question

I ran Enable-Migrations after much drama I finally got the command right so that it creates the Migrations directory within my project.

However, this is the file it gave me back.. I have moved the Using Statements to the top and removed the ones that were invalid, but that is all I changed.

Raw Code.. Errors are in the Image link above.

internal sealed class Configuration : DbMigrationsConfiguration<RapidDeploy.Models.BloggingContext>
{
    public Configuration()
    {
        AutomaticMigrationsEnabled = false;
    }

    protected override void Seed(RapidDeploy.Models.BloggingContext context)
    {
        //  This method will be called after migrating to the latest version.

        //  You can use the DbSet<T>.AddOrUpdate() helper extension method 
        //  to avoid creating duplicate seed data. E.g.
        //
        //    context.People.AddOrUpdate(
        //      p => p.FullName,
        //      new Person { FullName = "Andrew Peters" },
        //      new Person { FullName = "Brice Lambson" },
        //      new Person { FullName = "Rowan Miller" }
        //    );
        //
    }
}

Answer 1

I have no idea where you went wrong, but there is no Enable-Migrations command (or DbMigrationsConfiguration classes) in Entity Framework Core. Those are only an Entity Framework 6 thing.

Answer 2

Firstly lets get you on the right page...

https://docs.microsoft.com/en-us/ef/core/get-started/uwp/getting-started

Second the unfortunate news... but there appears someone has adapted it to have a seeding feature. Right not is not currently supported in the latest release by MS, its a second party that produced the code. It's an adaptation of the code that was previously in the EF6 release. Also keep in mind that code is based on Asp.net Core not UWP.

https://github.com/aspnet/EntityFramework/issues/629

Answer 3

Old question, but I hope it can help.

I had the same issue trying to use some EF6 code with a new EFCore project, I walked many tutorial to seed using the "Core" way, but I was not satisfied (I don't like to see seed data inside migrations...in my opinion the old school process, first update schema, then seed data, makes more sense).

By the way, I ended up with the most simple (but not obvious) solution: seed in Startup.cs > Configure method!

1. add your context as a param for the Configure method
2. call your SeedData method

public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ... , MyDBContext context)
{
   ...
   ContextInizializer.SeedData(context);
   ...
}

3. Add/update data

public class ContextInizializer
{
   public static void SeedData(RPToolDBContext context)
   {

      var item = new MyEntity()
      {
         Title = "MyTitle",
      };
      if(context.MyEntities.FirstOrDefault(f=>f.Title == item.Title)) {
         context.MyEntities.Add(item);
         context.SaveChanges();
      }
   }
}

Seed will run on every startup (in EF6 way was only after the update-database command), so be sure to check before adding stuff!

Done!

Answer 4

Add using System.Data.Entity.Migrations;

This would fix the issue for you.
The error is because you have not referenced the library which contains definition for DbMigrationCongfiguration .

Hope this helps.