Problem With Migrations

Rails
1

Hi, I’m following an example of a Rails Book (Practical JRuby on Rails
Projects, by Ola B.) and I’m stuck with a weird exception.

I have these 3 migration files, but when I run them (with rake
db:migrate) I see the following exception:

rake aborted!
CreateProductCategories is not missing constant ProductType!

Does anybody knows why? I append the 3 migrations below.
Thanks!

================================================
FILE 1:

class CreateProductTypes < ActiveRecord::Migration
class ProductType < ActiveRecord::Base; end
def self.up
create_table :product_types do |t|
t.column :name, :string
end
load_data
end

def self.load_data
ProductType.create :name => ‘Book’
ProductType.create :name => ‘Music’
ProductType.create :name => ‘Movie’
end

def self.down
drop_table :product_types
end
end

============================================
FILE 2

class CreateProducts < ActiveRecord::Migration
def self.up
create_table :products do |t|
t.column :name, :string
t.column :description, :text
t.column :product_type_id, :integer
t.column :price, :integer #in cents
end
end

def self.down
drop_table :products
end
end

===============================================
FILE 3

class CreateProductCategories < ActiveRecord::Migration

#Active record Class definitions.
class ProductType < ActiveRecord::Base; end
class ProductCategory < ActiveRecord::Base
belongs_to :product_type
end

def self.up
create_table :product_categories do |t|
t.column :product_type_id, :integer
t.column :name, :string
end

create_table :product_categories_products do |t|
  t.column :product_id, :integer
  t.column :product_category_id, :integer
end

load_data

end

def self.load_data
book = ProductType.find_by_name ‘Book’
music = ProductType.find_by_name ‘Music’
movie = ProductType.find_by_name ‘Movie’

%w(Computers Mysteries Crime).each do |c|
  ProductCategory.create :product_type => book, :name => c
end

%w(Jazz Rock Metal Punk).each do |c|
  ProductCategory.create :product_type => music, :name => c
end

%w(Action Comedy Thriller).each do |c|
  ProductCategory.create :product_type => movie, :name => c
end

end

def self.down
drop_table :product_categories_products rescue nil
drop_table :product_categories
end
end

2

class_name => ‘CreateProductCategories::ProductType’ did the trick!!!

Thank you so much Frederick!!

3

On 13 Aug 2008, at 00:45, Pablo F. wrote:

Hi, I’m following an example of a Rails Book (Practical JRuby on Rails
Projects, by Ola B.) and I’m stuck with a weird exception.

I have these 3 migration files, but when I run them (with rake
db:migrate) I see the following exception:

If you run them one at a time does it work ? (ie move migrations 2 and
3 out of the migrate folder for a minute, run db:migrate,move them
back again, run miograte again?)

Seems related to http://dev.rubyonrails.org/ticket/6272

in which case the problem is that the belongs_to :product_type is
looking for the wrong ProductType class. You might be able to guide it
on its way with class_name => ‘CreateProductCategories::ProductType’

Fred

4

On 13 Á×Ç, 18:46, Pablo F. [email protected] wrote:

class_name => ‘CreateProductCategories::ProductType’ did the trick!!!

Thank you so much Frederick!!
I think this will work too

class ProductType < ActiveRecord::Base; end
class CreateProductTypes < ActiveRecord::Migration
…
def self.load_data
ProductType.create :name => ‘Book’
ProductType.create :name => ‘Music’
ProductType.create :name => ‘Movie’
end
…
end