uninitialized constant CreateDb when using rake db:migrate

rubyonrails-talk
1

Does anyone have any idea why I might be getting this error? I'm using sqlite3 with Rails 1.2.3 and ruby 1.8.5 (2006-08-25) [i486-linux]

rake db:migrate --trace (in /home/robhu/incremental) ** Invoke db:migrate (first_time) ** Invoke environment (first_time) ** Execute environment ** Execute db:migrate rake aborted!

/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:266:in `load_missing_constant' /usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:452:in `const_missing' /usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/dependencies.rb:464:in `const_missing' /usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/inflector.rb:250:in `constantize' /usr/lib/ruby/gems/1.8/gems/activesupport-1.4.2/lib/active_support/core_ext/string/inflections.rb:148:in `constantize' /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/migration.rb:366:in `migration_class' /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/migration.rb:346:in `migration_classes' /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/connection_adapters/sqlite_adapter.rb:352:in `inject' /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/migration.rb:342:in `each' /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/migration.rb:342:in `inject' /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/migration.rb:342:in `migration_classes' /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/migration.rb:330:in `migrate' /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/migration.rb:297:in `up' /usr/lib/ruby/gems/1.8/gems/activerecord-1.15.3/lib/active_record/migration.rb:288:in `migrate' /usr/lib/ruby/gems/1.8/gems/rails-1.2.3/lib/tasks/databases.rake:4 /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:392:in `call' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:392:in `execute' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:392:in `each' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:392:in `execute' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:362:in `invoke' /usr/lib/ruby/1.8/thread.rb:135:in `synchronize' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:355:in `invoke' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:1739:in `top_level' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:1739:in `each' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:1739:in `top_level' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:1761:in `standard_exception_handling' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:1733:in `top_level' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:1711:in `run' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:1761:in `standard_exception_handling' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/lib/rake.rb:1708:in `run' /usr/lib/ruby/gems/1.8/gems/rake-0.7.3/bin/rake:7 /usr/bin/rake:16:in `load' /usr/bin/rake:16

trueman% cat db/migrate/001_create_db.rb class CreateTasks < ActiveRecord::Migration   def self.up     create_table :tasks do |t|       t.column :name, :string     end   end

  def self.down     drop_table :tasks   end end

-Rob

2

Does anyone have any idea why I might be getting this error? I'm using sqlite3 with Rails 1.2.3 and ruby 1.8.5 (2006-08-25) [i486-linux]

Aha. The reason was something to do with creating db/migrate/001_foo.rb myself. When I used the generator it worked fine.

-Rob

3

The migration code looks for a class based on the file name of the migration. So since your migration file is named 001_create_db.rb, it strips off the 001_ part and turns create_db into the class CreateDb and tries to peform CreateDb.up, which can't be found.

So you need to either name the migration file as 001_create_tasks.rb, or rename the class to CreateDb.

You found out that the generator keeps things in order for you. If you need a migration to add a table, I suggest you generate a model instead of a migration. The model generator will create a migration for you as it creates the model skeleton.