Question

Experienced with Rails / ActiveRecord 2.1.1

• You create a first version with (for example) ruby script\generate scaffold product title:string description:text image_url:string
• This create (for example) a migration file called 20080910122415_create_products.rb
• You apply the migration with rake db:migrate
• Now, you add a field to the product table with ruby script\generate migration add_price_to_product price:decimal
• This create a migration file called 20080910125745_add_price_to_product.rb
• If you try to run rake db:migrate, it will actually revert the first migration, not apply the next one! So your product table will get destroyed!
• But if you ran rake alone, it would have told you that one migration was pending

Pls note that applying rake db:migrate (once the table has been destroyed) will apply all migrations in order.

The only workaround I found is to specify the version of the new migration as in:

rake db:migrate version=20080910125745 

So I’m wondering: is this an expected new behavior?

Answer 1

You should be able to use

rake db:migrate:up  

to force it to go forward, but then you risk missing interleaved migrations from other people on your team

if you run

rake db:migrate  

twice, it will reapply all your migrations.

I encounter the same behavior on windows with SQLite, it might be a bug specific to such an environment.

Edit — I found why. In the railstie database.rake task you have the following code :

desc 'Migrate the database through scripts in db/migrate. Target specific version with VERSION=x. Turn off output with VERBOSE=false.' task :migrate => :environment do   ActiveRecord::Migration.verbose = ENV['VERBOSE'] ? ENV['VERBOSE'] == 'true' : true   ActiveRecord::Migrator.migrate('db/migrate/', ENV['VERSION'] ? ENV['VERSION'].to_i : nil)   Rake::Task['db:schema:dump'].invoke if ActiveRecord::Base.schema_format == :ruby end 

Then in my environment variables I have

echo %Version% #=> V3.5.0f 

in Ruby

ENV['VERSION'] # => V3.5.0f ENV['VERSION'].to_i #=>0 not nil ! 

thus the rake task calls

ActiveRecord::Migrator.migrate('db/migrate/', 0) 

and in ActiveRecord::Migrator we have :

class Migrator#:nodoc:   class << self     def migrate(migrations_path, target_version = nil)       case         when target_version.nil?              then up(migrations_path, target_version)         when current_version > target_version then down(migrations_path, target_version)         else                                       up(migrations_path, target_version)       end     end 

Yes, rake db:migrate VERSION=0 is the long version for rake db:migrate:down

Edit – I would go update the lighthouse bug but I the super company proxy forbids that I connect there

In the meantime you may try to unset Version before you call migrate …