Entity Framework: Using Multiple Custom History Context

Question

I have the code that map the __MigrationHistory to the existing database table.

namespace Alvin_CMS.Migrations
{
    public class CustomHistoryContext : HistoryContext
    {
        public CustomHistoryContext(DbConnection dbConnection, string defaultSchema)
        : base(dbConnection, defaultSchema)
        {
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
            modelBuilder.Entity<HistoryRow>().ToTable(tableName: "__MigrationHistory", schemaName: "dbo");
            //modelBuilder.Entity<HistoryRow>().Property(p => p.MigrationId).HasColumnName("Migration_ID");
        }
    }

    public class CustomHistoryConfiguration : DbConfiguration
    {
        public CustomHistoryConfiguration()
        {
            this.SetHistoryContext("System.Data.SqlClient",
            (connection, defaultSchema) => new CustomHistoryContext(connection, "dbo"));
        }
    }
}

Also I have another custom history context:

namespace EAccounting.Migrations
{
    public class CustomHistoryContext : HistoryContext
    {
        public CustomHistoryContext(DbConnection dbConnection, string defaultSchema)
            : base(dbConnection, defaultSchema)
        {
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
            modelBuilder.Entity<HistoryRow>().ToTable(tableName: "__MigrationHistory", schemaName: "EAccounting");
            //modelBuilder.Entity<HistoryRow>().Property(p => p.MigrationId).HasColumnName("Migration_ID");
        }
    }

    public class CustomHistoryConfiguration : DbConfiguration
    {
        public CustomHistoryConfiguration()
        {
            this.SetHistoryContext("System.Data.SqlClient",
            (connection, defaultSchema) => new CustomHistoryContext(connection, "EAccounting"));
        }
    }
}

And I call this in my code:

Database.SetInitializer(new MigrateDatabaseToLatestVersion<EAccounting.Models.EAccountingMigrationDBContext, EAccounting.Migrations.Configuration>());

I have multiple databases which have their own custom migration history context. How can I let the database initializer for the migration history to choose which history context they will use?

mike mckechnie · Accepted Answer · 2017-01-12 13:19:09Z

I have a system with two different DbContext subclasses in two different assemblies, and these two contexts use two different HistoryContexts. The trick for me was to use two different HistoryContext tables, and to ensure that the DbMigrationsConfiguration subclass for each DbContext subclass includes code that registers the right HistoryContext subclass when the database initializes.

base db migration class:

   public class DbMigrationsConfigurationBase<TContext> : DbMigrationsConfiguration<TContext>, IDbMigrationsConfiguration<TContext> where TContext : DbContext, IDbContext
{
    public DbMigrationsConfigurationBase(Func<DbConnection, string, HistoryContext> historyContextFactory)
    {
        AutomaticMigrationsEnabled = true;
        AutomaticMigrationDataLossAllowed = true;
        MigrationsDirectory = @"Migrations";
        RegisterHistoryContextFactory(historyContextFactory);
    }

    private void RegisterHistoryContextFactory(Func<DbConnection, string, HistoryContext> historyContextFactory)
    {
        foreach (ConnectionStringSettings connectionString in ConfigurationManager.ConnectionStrings)
        {
            if (!string.IsNullOrEmpty(connectionString.ProviderName))
            {
                SetHistoryContextFactory(connectionString.ProviderName, historyContextFactory);
            }
        }
    }

    public IDbMigrator GetMigrator()
    {
        return new DbMigratorWrapper(new DbMigrator(this));
    }
}

Example context-specific migration config class:

    public sealed class MySpecialDatabaseMigrationConfiguration : DbMigrationsConfigurationBase<MySpecialDatabase>
{
    private static readonly Func<DbConnection, string, HistoryContext> HistoryContextFactory =
        (connection, schema) => new MySpecialDatabaseHistoryContext(connection, schema);
    public MySpecialDatabaseMigrationConfiguration(): base(HistoryContextFactory)
    {
        ContextKey = "MyNamespace.MySpecialDatabase";
    }
}

Then in my database initializer I ensure the migration config is instantiated at initialization time...

    public class CreateOrMigrateDatabaseInitializer<TContext, TConfiguration> : IDatabaseInitializer<TContext>
    where TContext : DbContext, IDbContext
    where TConfiguration : IDbMigrationsConfiguration<TContext>, new()
{
    private readonly string _connection;

    public CreateOrMigrateDatabaseInitializer(string connection, ILogger logger = null)
    {
        Contract.Requires(!string.IsNullOrEmpty(connection), "connection");
        _connection = connection;
    }

    public void InitializeDatabase(TContext context)
    {
        Contract.Requires(context != null, "context");

        IDbMigrationsConfiguration<TContext> configuration = new TConfiguration()
        {
            TargetDatabase = new DbConnectionInfo(_connection)
        };

        if (!context.Database.Exists() || !context.Database.CompatibleWithModel(throwIfNoMetadata: false))
        {
            var migrator = configuration.GetMigrator();

            foreach (string s in migrator.GetPendingMigrations())
            {
                migrator.Update(s);
            }
        }

        Seed(context);

        context.SaveChanges();
    }

}

Kirsten · Accepted Answer · 2018-05-15 19:59:42Z

0

I am running 6.2.0 with code first. I just use a different schema for each DbContext

Inside the DbContext I set the default schema

  protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        modelBuilder.HasDefaultSchema("schema1");
    }

this causes a separate __MigrationHistory table for each DbContext

answered May 15, 2018 at 19:59

Kirsten

18.8k52 gold badges213 silver badges368 bronze badges

Comments

Henfs · Accepted Answer · 2020-03-01 16:49:15Z

0

You have to add attribute above the context, juts like this:

[DbConfigurationType(typeof(CustomeConfiguration))]

Then try to register the configuration before initialize the context in global asax or in the app config.

DbConfiguration.SetConfiguration(new TDBConfigurations());

Reference: https://learn.microsoft.com/en-us/ef/ef6/fundamentals/configuring/code-based

edited Mar 1, 2020 at 16:49

Henfs

5,45912 gold badges33 silver badges48 bronze badges

answered Mar 1, 2020 at 16:05

khadija houtat

316 bronze badges

Collectives™ on Stack Overflow

Entity Framework: Using Multiple Custom History Context

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related