How to run Seed() method of Configuration class of

问题:

I have 2 questions:

1) How can I run Seed() method from the package-manager console without updating-database model?

2) Is there a way how to call Seed() method in the code?

Thx for any advice.

回答1:

Answering your first question. Create a Migration by running add-migration SeedOnly

Clear out all Up() and Down() code generated if there was any pending changes

public partial class SeedOnly : DbMigration
{
    public override void Up()
    {
    }

    public override void Down()
    {
    }
}

Then you can Target a Specific Migration by running update-database -TargetMigration SeedOnly in the Package Manager console

回答2:

After research I finally found the workaround for this issue:

1) Make Configuration public:

public sealed class Configuration : DbMigrationsConfiguration<YourContextClassHere>

2) Add the code below anywhere. It will run the latest migration and update your database:

Configuration configuration = new Configuration();
configuration.ContextType = typeof(YourContextClassHere);
var migrator = new DbMigrator(configuration);

//This will get the SQL script which will update the DB and write it to debug
var scriptor = new MigratorScriptingDecorator(migrator);
string script = scriptor.ScriptUpdate(sourceMigration: null, targetMigration: null).ToString();
Debug.Write(script);

//This will run the migration update script and will run Seed() method
migrator.Update();

回答3:

Answering Question #2: Extract all the code from the Seed() method to another class. Then call that from within the Seed() method from the Configuration class:

    protected override void Seed(DbContext ctx)
    {
        new DatabaseSeed().Seed(ctx);
    }

Then you can call it from anywhere:

    new DatabaseSeed().Seed(new DbContext());

回答4:

Answer question 1:

People would usually work around this by either:

1. Making a temporary artificial change to the model
2. Switching to DropCreateDatabaseAlways, with the consequence that the database is often dropped and recreated when it is not needed
3. Manually deleting the database

reference: http://blog.oneunicorn.com/2013/05/28/database-initializer-and-migrations-seed-methods/

回答5:

This is not exactly what you are looking for, but however take a look: Running Entity Framework Migrations via command line prompt This may help you or someone to forget application based database migration, because you can easily make scripts to run automatically...

回答6:

If you use context initiliazer as MigrateDatabaseToLatestVersion, seed method in configuration should be run automatically. Don't think you need to call it manually.

回答7:

Add a new public method into the Configuration class. The new method only calls the protected method Seed:

public void RunSeed(DbContext db)
{
    Seed(db);
}

Then call the new method from eg. a unit test:

var db = new SomeDbContext();
var configuration = new Configuration();
configuration.RunSeed(db);

回答8:

If you want to Update-Database --Target-Migration xxx and you are surprised as i was that seed() method has not been run, you can try to git stash all your changes, generate database from previous version using Update-Database (to last revision which runs seed() always) and git stash apply then.

It is ugly workaround but it helped me.

Btw: don't forget to stage your changes before stashing