Rails 2: joint multi table - ruby-on-rails

Question

Sorry, i'am newbie
I have database:
Migrate
-Mst_group tble
class CreateMstGroups < ActiveRecord::Migration
def self.up
create_table :mst_groups do |t|
t.string :group_name
end
end
end
-Mst_japan
class CreateMstJapans < ActiveRecord::Migration
def self.up
create_table :mst_japans do |t|
t.string :name_level
end
end
end
-Tbl_user
class CreateTblUsers < ActiveRecord::Migration
def self.up
create_table :tbl_users do |t|
t.string :login_name, :null =>false,:limit =>15
t.string :password,:null =>false,:limit =>50
t.string :full_name,:null =>false
t.string :full_name_kana
t.string :email,:null =>false
t.string :tel,:null =>false,:limit =>15
t.date :birthday,:null =>false
t.references :mst_groups
end
end
end
-Tbl_detail_user_japan
class CreateTblDetailUserJapans < ActiveRecord::Migration
def self.up
create_table :tbl_detail_user_japans do |t|
t.date :start_date
t.date :end_date
t.integer :total
t.references :tbl_users
t.references :mst_japans
end
end
end
Model
class MstGroup < ActiveRecord::Base
has_many :tbl_users
end
class MstJapan < ActiveRecord::Base
has_many :tbl_detail_user_japans
end
class TblUser < ActiveRecord::Base
belongs_to :mst_group
has_one :tbl_detail_user_japan
end
class TblDetailUserJapan < ActiveRecord::Base
belongs_to :tbl_user
belongs_to :mst_japan
end
Controller
def index
#user= ???????
end
How to write command select : login_name, full_name, full_name_kana, email, tel, group_name, name_lever, start_date, end_date, total in controller

Answer 1

It depends on how you want to retrieve the User object. You need to tell Rails how to find the TblUser object. If, for example, the user ID is known, let's say in a variable called 'id' then you would do:
def index
#user=TblUser.find(id)
end
It depends on your application logic how Rails would know which user you need. You may need an input from the user in case of log in, etc.
(Typically in Rails you would call the table 'Users', by convention tables and classes have the same name and then you wouldn't need to call the class TblUser)
That is all you need in the controller, you don't need to tell it which fields you want.
Then in the View you can access all the fields:
Fields on TblUser, example:
<%= #user.email %>
You can access the fields from related objects through the relations, example:
<%= #user.mst_group.group_name %>
Hope that helps to get you started.