Migrations, the "right" way

rubyonrails-talk
1

I've got the Agile Web Development with Rails book that tells me to do migrations different than the what is explained on api.rubyonrails.org under ActiveRecord::Migration

What is the "best" or "right" syntax of migrations?

2

For those of us who don’t own the book,

How does the book tell you to do it?

ActiveRecord::Migration on the api.rubyonrails.org seems to be the new syntax, where AWDWR will probably be the older (but not deprecated) syntax.

3

Sexy migrations is syntactic sugar. It is generally preferred.

4

Here is an example from the book:

class CreateProducts < ActiveRecord::Migration   def self.up     create_table :products do |t|       t.column :title, :string       t.column :description, :text       t.column :image_url, :string     end   end

  def self.down     drop_table :products   end end

5

what are "sexy migrations"?

6

Basically, the rails core realized that the 'column' call was redundant within the context of a table definition so you can now do the following

create_table :products do |t|   t.column :title, :string   t.column :description, :text   t.column :image_url, :string end

Like this:

create_table :products do |t|   t.string :title   t.text :description   t.string :image_url end

..or..

create_table :products do |t|   t.string :title, :image_url   t.text :description end

What I personally find "sexier" is the syntax that makes references to other tables more explicit. For example, if a line_item referred to the product table you used to do this:

create_table :line_items do |t|   t.column :product_id, :integer end

But now...

create_table :line_items do |t|   t.references :product end

And you can have even sexier polymorphic associations

create_table :addresses do |t|   t.references :addressable, :polymorphic=>true end

That gives you :addressable_type and :addressable_id with a syntax that looks remarkably like the one you'll have in your Address class.

7

Thanks AndyV

When I try this syntax I get this error:

rake aborted! undefined method `integer' for #<ActiveRecord::ConnectionAdapters::TableDefinition:0x421d3e8>

I just updated rails to 2.0.2, is there something I'm missing?

8

nevermind, I found the answer here: http://www.railsforum.com/viewtopic.php?id=17431

9

what are “sexy migrations”?

Migrations with sexy lace and a single rose clutched between it’s teeth:

Instead of your old, tired cellulite ridden migrations:

def self.up

create_table :posts do |t| t.column :created_at, :datetime

t.column :updated_at, :datetime t.column :title, :string

t.column :slug, :string t.column :text, :text t.column :user_id, :integer

end

end

Your younger, fresh, sexy migrations: def self.up create_table :posts do |t| t.timestamps t.string :title, :slug t.text :text t.references :user end end

insert mandatory wolf whistle here