How to revert few values which were set on a rollback during migration

Question

We set few values on a certain row during migration, how do we handle this on a rollback. I would like to set empty null values on down

def up
f = Foo.where(:name => 'some').first
f.update_attributes(:val1 => 'val1', :val2 => 'val2');
end

def down
# What should we do here to revert the migration
end

Answer 1

You can do rake db:rollback STEP=2.

You can substitute 2 for however many migrations you want to go back.

You can also try this:

def up
    f = Foo.where(:name => 'some').first
    f.update_attributes(:val1 => 'val1', :val2 => 'val2');
    end

    def down
    f = Foo.where(:name => 'some').first
    f.update_attributes(:val1 => nil, :val2 => nil);
    end

Answer 2

rake db:migrate:down VERSION=version_number

def up
  f = Foo.where(:name => 'some').first
  f.update_attributes(:val1 => 'val1', :val2 => 'val2')
end

def down
  f = Foo.where(:name => 'some').first
  f.update_attributes(:val1 => nil, :val2 => nil) if f.present?
end