model reference

rubyonrails-talk
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

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.