Model reference

Rails
#1

hi

I am tanizawa
I am searching how to add reference of two same table.
Please teach me how to add .
exmple:
class CreateLocationjs < ActiveRecord::Migration
def change
create_table :locationjs do |t|
t.references :locationm <----start point
<— I want to add end point
field.

#2

On Mon, Jun 18, 2012 at 7:38 AM, tanizawa [email protected] wrote:

                <--- I want to add end point

field.

Not sure what your exact question is, but this example below
references a location 2 times:

Create models:

rails g model location name:string
rails g model route

Add associations between models:

in Location, add:
has_many :routes

in Route, add:
belongs_to :location_start, :class_name => Location, :foreign_key
=> “location_start_id”
belongs_to :location_end, :class_name => Location, :foreign_key
=> “location_end_id”

Define foreign keys in db migration:

class CreateRoutes < ActiveRecord::Migration
def change
create_table :routes do |t|
t.references :location_start
t.references :location_end

  t.timestamps
end

end
end

Now in console:

munich = Location.new
munich.name = “Munich”; munich.save!

tokyo = Location.new
tokyo.name = “Tokyo”; tokyo.save!

route = Route.new
route.location_start = munich
route.location_end = tokyo
route.save!

#3

Thank you for your code.
I couldn’t have done it without you.
I understand how to add some reference for same table.

2012/6/18 Patrick M. [email protected]