The need for that code was discovered by Insoshi contributor Evan
Dorn, who found that changes in models (adding validations, for
example) could break the migration code. Declaring the model in the
migration solves this problem, though I admit it's a bit mysterious.
By the way, it's not as easy as bypassing the validations by writing
something like Forum.new(...).save(false). In migration 13, which
adds an admin user, we have code like this:
class Person < ActiveRecord::Base
end
.
.
.
def self.up
add_column :people, :admin, :boolean, :default => false, :null => false
.
.
.
person.admin = true
Without the "class Person < ActiveRecord::Base" part, the
"person.admin" step fails, because the Person model doesn't have an
admin column when the migration runs. Again, for somewhat opaque
reasons, the model declaration solves the problem.
I've added an explanatory comment to the first occurrence of this code
(the one you discovered) to allay confusion in the future.
Thanks,
Michael
On Thu, Oct 16, 2008 at 7:10 AM, Thomas Blumenfeld
<[EMAIL PROTECTED]> wrote:
>
> Hi!
>
> I was looking into the code of the 005_create_forums.rb migration, it is
> also present in the last stable release.
>
> Here it is:
> class CreateForums < ActiveRecord::Migration
>
> class Forum < ActiveRecord::Base
> end
>
> def self.up
> create_table :forums do |t|
> t.string :name
> t.text :description
> t.integer :topics_count, :null => false, :default => 0
>
> t.timestamps
> end
> Forum.create!(:name => "Discussion forum",
> :description => "The main forum")
> end
>
> def self.down
> drop_table :forums
> end
> end
>
> What does those lines mean?
>
> class Forum < ActiveRecord::Base
> end
>
> Thx
>
> Thomas
>
>
> >
>
--
Michael Hartl
Insoshi social software
http://insoshi.com/
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