Useful Entity Framework's DbContext Database Initializers

DropCreateDatabaseAlwaysAndSeed.cs

using Boundaries.Persistence.Contexts;
using Boundaries.Persistence.Migrations;
using System.Data.Entity;
using Validation;

namespace DatabaseInitializers
{
    public sealed class DropCreateDatabaseAlwaysAndSeed : DropCreateDatabaseAlways<MyDbContext>
    {
        public override void InitializeDatabase(MyDbContext context)
        {
            Requires.NotNull(context, nameof(context));
            
            // This tells the database to close all connections and rolback open transactions.
            // The intent to avoid any open database connections errors during database drop.
            if (context.Database.Exists())
            {
                context.Database.ExecuteSqlCommand(
                    TransactionalBehavior.DoNotEnsureTransaction,
                    $"ALTER DATABASE [{context.Database.Connection.Database}] SET SINGLE_USER WITH ROLLBACK IMMEDIATE");
            }

            base.InitializeDatabase(context);
        }

        protected override void Seed(MyDbContext context)
        {
          // Seed here...
        }
    }
}

ForceDropCreateDatabaseAlways.cs

using System.Data.Entity;
using Validation;

namespace DatabaseInitializers
{
    /// <summary>
    /// Drops the database on application startup (the first time only), recreates it based on the model's
    /// schema and nothing more. It does NOT add any seed data, so the resulting application will have 
    /// an empty database.
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public sealed class ForceDropCreateDatabaseAlways : DropCreateDatabaseAlways<MyDbContext>
    {
        public override void InitializeDatabase(MyDbContext context)
        {
            Requires.NotNull(context, nameof(context));
            
            // This tells the database to close all connections and rolback open transactions.
            // The intent to avoid any open database connections errors during database drop.
            if (context.Database.Exists())
            {
                context.Database.ExecuteSqlCommand(
                    TransactionalBehavior.DoNotEnsureTransaction, 
                    $"ALTER DATABASE [{context.Database.Connection.Database}] SET SINGLE_USER WITH ROLLBACK IMMEDIATE"); 
            }

            base.InitializeDatabase(context);
        }
    }
}

MigrateDatabaseToLatestVersionAndSeedOnce.cs

using Migrations;
using System.Data.Entity;
using Validation;

namespace DatabaseInitializers
{
    /// <summary>
    /// If no database is created at startup, it will create one and perform a once time seed.
    /// If there is already one created, it will update its schema according to the current state of the <see cref="DbContext"/>'s 
    /// models without dropping it, which means that it will retain previous data, without adding new one. 
    /// If this is used on an empty database, the deployed application will have an updated schema but without any data. 
    /// </summary>
    /// <typeparam name="TContext"></typeparam>
    /// <typeparam name="TConfig"></typeparam>
    /// <remarks>
    /// IMPORTANT: To use this option, your app's <see cref="DbContext"/>'s Configuration must be set to AutomaticMigrationsEnabled = true. 
    /// If you don't set this, EF's Code First will try to use the migrations you've created, which will not necessarily 
    /// match with the migrations already applied to the existing database and an error will occur when EF try to access/update it.
    /// </remarks>
    public sealed class MigrateDatabaseToLatestVersionAndSeedOnce : MigrateDatabaseToLatestVersion<MyDbContext, Configuration>
    {
        public MigrateDatabaseToLatestVersionAndSeedOnce()
        { 
        }

        public MigrateDatabaseToLatestVersionAndSeedOnce(string connectionStringName)
            : base(connectionStringName)
        {
        }

        public override void InitializeDatabase(MyDbContext context)
        {
            Requires.NotNull(context, nameof(context));
            
            bool existed = context.Database.Exists();
            base.InitializeDatabase(context);

            if (!existed)
            {
                OneTimeSeed(context); 
            }
        }

        /// <summary>
        /// This Seed method will run after initialization only if the database is not created on application startup.
        /// It is used to inject data necessary for production into the database (like Module info or User accounts).
        /// </summary>
        /// <param name="context"></param>
        private void OneTimeSeed(MyDbContext context)
        {
          // Seed here...  
        }
    }
}