# Migration problem **URL:** \ **Category:** Rails\ **Created:** [December 3, 2007, 8:01pm UTC](https://www.ruby-forum.com/t/migration-problem/122000 "2007-12-03T20:01:52Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![winslowly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/85f322/32.png) [@winslowly](https://www.ruby-forum.com/u/winslowly)\ **Post date:** [December 3, 2007, 8:01pm UTC](https://www.ruby-forum.com/t/migration-problem/122000/1 "2007-12-03T20:01:52Z")
I use the following steps to create a model and migrate. However when it comes running ‘rake db:migrate’ it gave me the following errors. I suspect it is due to the fact that I was trying to put everything about blog in its own folder. Is this possible with migration or is there a different way of putting topics into their own folder. Here are the steps that I did. 1. ruby script/generate model ‘blog/post’ 2. rake db:migrate It tried to create a constant ‘CreateBlogPosts’ which I don’t think its suppose to. Anyone who can help or suggest something would be greatly appreciated. If I can’t do it this way I’ll go back to using ‘script/generate model Post’. Thanks in advance The error it threw are: (in /home/naruto/sites/geneva) \*\* Invoke db:migrate (first\_time) \*\* Invoke environment (first\_time) \*\* Execute environment \*\* Execute db:migrate rake aborted! uninitialized constant CreateBlogPosts /home/naruto/sites/geneva/vendor/rails/activerecord/lib/…/…/ activesupport/lib/active\_support/dependencies.rb:266:in `load_missing_constant' /home/naruto/sites/geneva/vendor/rails/activerecord/lib/../../ activesupport/lib/active_support/dependencies.rb:452:in`const\_missing’ /home/naruto/sites/geneva/vendor/rails/activerecord/lib/…/…/ activesupport/lib/active\_support/dependencies.rb:464:in `const_missing' /home/naruto/sites/geneva/vendor/rails/activerecord/lib/../../ activesupport/lib/active_support/inflector.rb:250:in`constantize’ /home/naruto/sites/geneva/vendor/rails/activerecord/lib/…/…/ activesupport/lib/active\_support/core\_ext/string/inflections.rb:148:in `constantize' /home/naruto/sites/geneva/vendor/rails/activerecord/lib/active_record/ migration.rb:366:in`migration\_class’ /home/naruto/sites/geneva/vendor/rails/activerecord/lib/active\_record/ migration.rb:346:in `migration_classes' /home/naruto/sites/geneva/vendor/rails/activerecord/lib/active_record/ connection_adapters/mysql_adapter.rb:248:in`inject’ /home/naruto/sites/geneva/vendor/rails/activerecord/lib/active\_record/ migration.rb:342:in `each' /home/naruto/sites/geneva/vendor/rails/activerecord/lib/active_record/ migration.rb:342:in`inject’ /home/naruto/sites/geneva/vendor/rails/activerecord/lib/active\_record/ migration.rb:342:in `migration_classes' /home/naruto/sites/geneva/vendor/rails/activerecord/lib/active_record/ migration.rb:330:in`migrate’ /home/naruto/sites/geneva/vendor/rails/activerecord/lib/active\_record/ migration.rb:297:in `up' /home/naruto/sites/geneva/vendor/rails/activerecord/lib/active_record/ migration.rb:288:in`migrate’ /home/naruto/sites/geneva/vendor/rails/railties/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/gems/1.8/gems/rake-0.7.3/lib/rake.rb:355: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 ---
**Author:** ![winslowly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/85f322/32.png) [@winslowly](https://www.ruby-forum.com/u/winslowly)\ **Post date:** [December 3, 2007, 8:08pm UTC](https://www.ruby-forum.com/t/migration-problem/122000/2 "2007-12-03T20:08:23Z")
i got a similar error once, when trying to run migrate on a file where the classname didn’t match the filename so if you have a migration file like 001\_create\_blog\_posts.rb your class definition in the file must be: class CreateBlogPosts \< ActiveRecord::Migration nothing else is allowed, camelcase must match underscores ---
**Author:** ![winslowly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/85f322/32.png) [@winslowly](https://www.ruby-forum.com/u/winslowly)\ **Post date:** [December 3, 2007, 8:15pm UTC](https://www.ruby-forum.com/t/migration-problem/122000/3 "2007-12-03T20:15:21Z")
thanks this worked. However, should migration have created the file properly like you mention instead of class CreatePosts \< ActiveRecord::Migration? On Dec 3, 1:08 pm, Thorsten M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![winslowly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/85f322/32.png) [@winslowly](https://www.ruby-forum.com/u/winslowly)\ **Post date:** [December 3, 2007, 8:20pm UTC](https://www.ruby-forum.com/t/migration-problem/122000/4 "2007-12-03T20:20:03Z")
winslowly wrote: > thanks this worked. However, should migration have created the file > properly like you mention instead of class CreatePosts \< > ActiveRecord::Migration? > > On Dec 3, 1:08 pm, Thorsten M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) only with that syntax: ruby script/generate model ‘blog\_posts’ your version: ruby script/generate model ‘blog/post’ isn’t clear to me, maybe to generate a model in a subdirectory? i would expect it to generate an error, but sometimes rails is a bit too smart and makes ‘something’ out of the input. ---
**Author:** ![winslowly](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/w/85f322/32.png) [@winslowly](https://www.ruby-forum.com/u/winslowly)\ **Post date:** [December 3, 2007, 8:24pm UTC](https://www.ruby-forum.com/t/migration-problem/122000/5 "2007-12-03T20:24:16Z")
yeah, I was trying to put all models belonging to blog inside its own subdirectory. Again thanks for the help. On Dec 3, 1:20 pm, Thorsten M. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)