Code-First Migration Process: What part am I missing?

Question

My steps:

1) Create my database in SSMS with the query

/* Execute in SQL Server Management Studio prior to building data model(s) */

C         


        

Answer 1

Your database context definition should look something like this:

public class ApplicationDbContext: DbContext
{
    public ApplicationDbContext() : base("connectionString")
    {
    }

    public DbSet Scores { get; set; }
    public DbSet GameLogs { get; set; }
    public DbSet IPs { get; set; }
    public DbSet BannedIPs { get; set; }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        // modelBuilder.Conventions.Remove();
    }
}

it inherits from DbContext and defines the structure of your object model.

Your DbSet(s) should be mapped to your classes:

• Scores
• GameLogs
• IPs
• BannedIPs

As you can see the constructor needs a connection string:

public ApplicationDbContext() : base("connectionString")
{
}

which must be defined in your web.config (or app.config):

inside section. I've used localhost here but, of course, you can use your remote database.

Now from Package Manager Console you must have enabled the migration with Enable-Migrations.
This command will build the configuration file which should look something like this:

internal sealed class Configuration : DbMigrationsConfiguration
{
        public Configuration()
        {
            AutomaticMigrationsEnabled = true;
        }

        protected override void Seed(MigratingDatabase.SchoolContext context)
        {

        }
}

what I can see in your Configuration class it inherits from the database context:

DbMigrationsConfiguration

but it is trying to seed a different object:

protected void Seed (SnakeGame.Migrations.SnakeDB context)
{

}

and, I guess, it should be:

protected void Seed (SnakeGame.Models.ApplicationDbContext context)
{

}

when everything is in place you can run:

Update-Database -Verbose

and it should build the database for you.

Another thing you have to do to enable the migration is change the constructor of the configuration class:

public Configuration()
{
    AutomaticMigrationsEnabled = true;
}

using AutomaticMigrationsEnabled = true.