# Why is this migration trying to re-create schema\_info? **URL:** \ **Category:** Rails\ **Created:** [November 6, 2007, 2:00pm UTC](https://www.ruby-forum.com/t/why-is-this-migration-trying-to-re-create-schema-info/119370 "2007-11-06T14:00:31Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![fredistic](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/a8b319/32.png) [@fredistic](https://www.ruby-forum.com/u/fredistic)\ **Post date:** [November 6, 2007, 2:00pm UTC](https://www.ruby-forum.com/t/why-is-this-migration-trying-to-re-create-schema-info/119370/1 "2007-11-06T14:00:31Z")
Postgresql Migration Failure on 4th migration (attachment\_fu). A migration fails mysteriously. The console says: rake aborted! uninitialized constant AttachmentImages The log says: SQL (0.000000) PGError: ERROR: relation “schema\_info” already exists : CREATE TABLE schema\_info (version integer) Of course it exists, it’s up to 3. The database is not modified. Rails 1.2.4, ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-mswin32] The failing migration looks okay to me: def self.up add\_column :images, :parent\_id, :integer add\_column :images, :content\_type, :string add\_column :images, :filename, :string add\_column :images, :thumbnail, :string add\_column :images, :size, :integer ``` add_index :images, :artist_id ``` end fredistic ---
**Author:** ![fredistic](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/a8b319/32.png) [@fredistic](https://www.ruby-forum.com/u/fredistic)\ **Post date:** [November 6, 2007, 3:36pm UTC](https://www.ruby-forum.com/t/why-is-this-migration-trying-to-re-create-schema-info/119370/2 "2007-11-06T15:36:30Z")
On 6 Nov 2007, at 12:59, fredistic wrote: > Postgresql Migration Failure on 4th migration (attachment\_fu). > A migration fails mysteriously. > > The console says: > rake aborted! > uninitialized constant AttachmentImages Is there a stack trace to go with that ? Fred ---
**Author:** ![fredistic](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/a8b319/32.png) [@fredistic](https://www.ruby-forum.com/u/fredistic)\ **Post date:** [November 6, 2007, 6:09pm UTC](https://www.ruby-forum.com/t/why-is-this-migration-trying-to-re-create-schema-info/119370/3 "2007-11-06T18:09:53Z")
On 11/6/07, fredistic [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > exists > : CREATE TABLE schema\_info (version integer) > > Of course it exists, it’s up to 3. Those are two different problems. The second is unrelated to the first and can be ignored. AR just blindly tries to create the schema\_info in every migration; it ignores the “already exists” problem. You need to investigate the AttachmentImages problem. ---
**Author:** ![fredistic](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/a8b319/32.png) [@fredistic](https://www.ruby-forum.com/u/fredistic)\ **Post date:** [November 6, 2007, 6:17pm UTC](https://www.ruby-forum.com/t/why-is-this-migration-trying-to-re-create-schema-info/119370/4 "2007-11-06T18:17:24Z")
fredistic wrote: > Postgresql Migration Failure on 4th migration (attachment\_fu). > A migration fails mysteriously. > > The console says: > rake aborted! > uninitialized constant AttachmentImages > > The log says: > SQL (0.000000) PGError: ERROR: relation “schema\_info” already > exists > : CREATE TABLE schema\_info (version integer) > > Of course it exists, it’s up to 3. > > The database is not modified. > > Rails 1.2.4, > ruby 1.8.6 (2007-03-13 patchlevel 0) [i386-mswin32] > > The failing migration looks okay to me: > def self.up > add\_column :images, :parent\_id, :integer > add\_column :images, :content\_type, :string > add\_column :images, :filename, :string > add\_column :images, :thumbnail, :string > add\_column :images, :size, :integer > > ``` > add_index :images, :artist_id > > ``` > > end The schema\_info error indicates that something may be borked in your migration naming. You have confirmed that you do not have two migrations whose file names differ only by the number prefix, right? If that is not the problem then what does your class attachment\_image(s???) \< ActiveRecord::Base in app/models/attachment\_image(s???).rb say? If that is consistent with your class name then what does your class attachment\_image(s???) \< ActiveRecord::Migration in the db/migrate/004\_attachment\_image(s???).rb migration file say? You may have a problem with the naming of your classes if in truth you use plural in some places and singular in others. Regards, ---
**Author:** ![fredistic](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/a8b319/32.png) [@fredistic](https://www.ruby-forum.com/u/fredistic)\ **Post date:** [November 6, 2007, 7:59pm UTC](https://www.ruby-forum.com/t/why-is-this-migration-trying-to-re-create-schema-info/119370/5 "2007-11-06T19:59:25Z")
I changed the name of the class to match the name of the .rb file and and it just worked. I did not understand they had to be the same. Perhaps I once knew and forgot? Thanks for all the help… On Nov 6, 7:17 pm, James B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![fredistic](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/a8b319/32.png) [@fredistic](https://www.ruby-forum.com/u/fredistic)\ **Post date:** [November 6, 2007, 8:11pm UTC](https://www.ruby-forum.com/t/why-is-this-migration-trying-to-re-create-schema-info/119370/6 "2007-11-06T20:11:08Z")
I changed the name of the class to match the name of the .rb file and and it just worked. I did not understand they had to be the same. Perhaps I once knew and forgot? Thanks for all the help… On Nov 6, 7:17 pm, James B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) ---
**Author:** ![fredistic](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/a8b319/32.png) [@fredistic](https://www.ruby-forum.com/u/fredistic)\ **Post date:** [November 6, 2007, 7:55pm UTC](https://www.ruby-forum.com/t/why-is-this-migration-trying-to-re-create-schema-info/119370/7 "2007-11-06T19:55:54Z")
F.C. asked for a stack trace. Changing the file name changes the name of the uninitialized constant that triggers the error, matching it. Here it is called 004\_imaginary.rb. So the "uninitialized constant’ it complains about is ‘Imaginary’. I’ve tried other names and the error message follows the file name. I can use rake db:migrate VERSION=2 and 3 to go back and forth without a problem. Putting in ‘VERSION=4’ results in identical error messages, of course. Schema\_info in the database is 3. > dir db\migrate Directory of C:\InstantRails\rails\_apps\g1\db\migrate 11/06/2007 03:42 PM . 11/06/2007 03:42 PM … 10/19/2007 03:44 PM 474 001\_create\_images.rb 10/19/2007 03:44 PM 612 002\_create\_users.rb 10/19/2007 03:44 PM 561 003\_more\_user.rb 11/06/2007 03:39 PM 767 004\_imaginary.rb 4 File(s) 2,414 bytes 2 Dir(s) 18,688,790,528 bytes free > rake --trace db:migrate > (in C:/InstantRails/rails\_apps/g1) > \*\* Invoke db:migrate (first\_time) > \*\* Invoke environment (first\_time) > \*\* Execute environment > \*\* Execute db:migrate > rake aborted! > uninitialized constant Imaginary > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.3/lib/ > active\_support/dependencies.rb:266:in `load_missing_constant' C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.3/lib/ active_support/dependencies.rb:452:in`const\_missing’ > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.3/lib/ > active\_support/dependencies.rb:464:in `const_missing' C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.3/lib/ active_support/inflector.rb:250:in`constantize’ > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activesupport-1.4.3/lib/ > active\_support/core\_ext/string/inflections.rb:148:in `constantize' C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.4/lib/ active_record/migration.rb:366:in`migration\_class’ > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.4/lib/ > active\_record/migration.rb:346:in `migration_classes' C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.4/lib/ active_record/connection_adapters/abstract_adapter.rb:128:in`inject’ > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.4/lib/ > active\_record/migration.rb:342:in `each' C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.4/lib/ active_record/migration.rb:342:in`inject’ > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.4/lib/ > active\_record/migration.rb:342:in `migration_classes' C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.4/lib/ active_record/migration.rb:330:in`migrate’ > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.4/lib/ > active\_record/migration.rb:297:in `up' C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/activerecord-1.15.4/lib/ active_record/migration.rb:288:in`migrate’ > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/rails-1.2.4/lib/tasks/ > databases.rake:4 > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake.rb: > 399:in `call' C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake.rb: 399:in`execute’ > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake.rb: > 399:in `each' C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake.rb: 399:in`execute’ > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake.rb: > 369:in `invoke' C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake.rb: 362:in`synchronize’ > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake.rb: > 362:in `invoke' C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake.rb: 1935:in`run’ > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake.rb: > 1935:in `each' C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/rake-0.7.2/lib/rake.rb: 1935:in`run’ > C:/InstantRails/ruby/lib/ruby/gems/1.8/gems/rake-0.7.2/bin/rake:7 > C:/InstantRails/ruby/bin/rake.bat:20:in `load’ > C:/InstantRails/ruby/bin/rake.bat:20 fredistic ---
**Author:** ![fredistic](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/f/a8b319/32.png) [@fredistic](https://www.ruby-forum.com/u/fredistic)\ **Post date:** [November 6, 2007, 9:37pm UTC](https://www.ruby-forum.com/t/why-is-this-migration-trying-to-re-create-schema-info/119370/8 "2007-11-06T21:37:28Z")
fredistic wrote: > I changed the name of the class to match the name of the .rb file and > and it just worked. I did not understand they had to be the same. > Perhaps I once knew and forgot? Thanks for all the help… > > On Nov 6, 7:17 pm, James B. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) Convention over configuration. Rails depends upon the contents of its project files having class names consistent with its conventions and maintaining the relationship of the class name to the name of the containing file is one of those conventions.