Question

I have a table students with field ward_id and I have to create a table named guardian_users with fields id,ward_id,email,guardian_id,hashed_password etc.

Now I have to add constraint foreign key. Any update/delete/edit/insertion in students should have same effect on guardian_users.

How can I do that in rails 2.3.5?

Table students exists but other one doesn’t exist yet.

Answer 1

You’ll either need the foreign_key_migrations plugin or the #execute method. Assuming you go with the plugin:

class CreateGuardianUsersTable < ActiveRecord::Migration
  def self.up
    create_table(:guardian_users) do |table|
      table.timestamps # I find them useful; YMMV
      table.integer :guardian_id
      table.integer :ward_id, :null => false, :references => [:students, :id]
      table.string :email
      table.string :heahead_password
    end
  end

  def self.down
    drop_table :guardian_users
  end
end

And in your models:

class GuardianUser < ActiveRecord::Base
  belongs_to :student
end

class Student < ActiveRecord::Base
  has_many guardian_users:, :foreign_key => 'ward_id', :class_name => 'GuardianUser', :dependent => :destroy
end