Add rake db:forward - opposite of db:rollback [#768 state:resolved]

Example:
  rake db:forward # performs the next migration
  rake db:forward STEP=4 # performs the next 4 migrations

Signed-off-by: Pratik Naik <pratiknaik@gmail.com>

2 files changed, 21 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/migration.rb b/activerecord/lib/active_record/migration.rb
index 3963baa6b8..d205e57db3 100644
--- a/activerecord/lib/active_record/migration.rb
+++ b/activerecord/lib/active_record/migration.rb
@@ -397,6 +397,16 @@ module ActiveRecord
         down(migrations_path, finish ? finish.version : 0)
       end
 
+      def forward(migrations_path, steps=1)
+        migrator = self.new(:up, migrations_path)
+        start_index = migrator.migrations.index(migrator.current_migration)
+
+        return unless start_index
+
+        finish = migrator.migrations[start_index + steps]
+        up(migrations_path, finish ? finish.version : 0)
+      end
+
       def up(migrations_path, target_version = nil)
         self.new(:up, migrations_path, target_version).migrate
       end
diff --git a/activerecord/test/cases/migration_test.rb b/activerecord/test/cases/migration_test.rb
index 72d4892435..f0f21615e0 100644
--- a/activerecord/test/cases/migration_test.rb
+++ b/activerecord/test/cases/migration_test.rb
@@ -1136,6 +1136,17 @@ if ActiveRecord::Base.connection.supports_migrations?
       assert_equal(0, ActiveRecord::Migrator.current_version)
     end
 
+    def test_migrator_forward
+      ActiveRecord::Migrator.migrate(MIGRATIONS_ROOT + "/valid", 1)
+      assert_equal(1, ActiveRecord::Migrator.current_version)
+
+      ActiveRecord::Migrator.forward(MIGRATIONS_ROOT + "/valid", 2)
+      assert_equal(3, ActiveRecord::Migrator.current_version)
+
+      ActiveRecord::Migrator.forward(MIGRATIONS_ROOT + "/valid")
+      assert_equal(3, ActiveRecord::Migrator.current_version)
+    end
+
     def test_schema_migrations_table_name
       ActiveRecord::Base.table_name_prefix = "prefix_"
       ActiveRecord::Base.table_name_suffix = "_suffix"