migration

Generating association while generating model

Dec 14th

Posted by Akhil Bansal in active_record

1 comment

May be you guys are already aware of, but in Rails 2.2 we can specify belongs_to association while generating model. So if we issue:

script/generate model Post title:string author:belongs_to

We will get a Post model like:

class Post < ActiveRecord::Base
  belongs_to :author
end

Also it will automatically add the foreign key column in the migration.

class CreatePosts < ActiveRecord::Migration
  def self.up
    create_table :posts do |t|
      t.string :title
      t.belongs_to :author

      t.timestamps
    end
  end

  def self.down
    drop_table :posts
  end
end

Nothing much but saves some keystrokes. :-)

, , , , , , ,

Migration: Adding/Removing columns are now much easier

Jan 23rd

Posted by Akhil Bansal in migration

8 comments

You may have noticed by now, that in Rails 2.0 changeset 7422, you can specify columns you want to add/remove in your migration by passing attribute:type pairs to the migration generator.

For example, lets assume that we need to add a column ‘role’ in users table(User model). In this case generate a migration like:

script/generate migration AddRoleToUser role:string

Output:

class AddRoleToUser < ActiveRecord::Migration
  def self.up
    add_column :users, :role, :string
  end

  def self.down
    remove_column :users, :role
  end
end

Here AddRoleToUser plays the main role. ‘Add’ specifies the we want to add column(s) and ‘User’ separated by ‘To’ specifies the table.

Similarly, if we need to remove a column ‘role’ :

 script/generate migration RemoveRoleFromUser role:string

Output:

class RemoveRoleFromUser < ActiveRecord::Migration
  def self.up
    remove_column :users, :role
  end

  def self.down
    add_column :users, :role, :string
  end
end

Here RemoveRoleFromUser plays the main role. ‘Remove’ specifies the we want to remove column(s) and ‘User’ separated by ‘From’ specifies the table.

Isn’t it cool?