active record multiple table insert

rubyonrails-talk
1

If I have a shelf table, card table and port table how do I go about inserting data into each table relating one to another?

Insert name of the shelf and # of cards the shelf has, and the name of each card and other data, and how many ports on each card?

Shelf has many cards. Card has many ports.

2

Well, there are a few approaches you could take to do this.

1. Controller actions defining a logical "function" Make the process of inserting all the records, externally, as a controller action. Allowing you to do them sequentially.

2. Use ActiveRecord hooks Take a look at the hooks like #after_save, #before_save, etc.

3

Active Record gives you API to build, save, and retrieve this stuff at a high-level. In particular it handles recursive save and FK assignment for you:

shelf = Shelf.new(:name => 's')

card1 = shelf.cards.build(:name => 'c1') card2 = shelf.cards.build(:name => 'c2')

1.times {card1.ports.build} 2.times {card2.ports.build}

shelf.save

puts "dumping shelf #{shelf.name}, which has #{shelf.cards.count} cards" for card in shelf.cards   puts "dumping card #{card.name}, which has #{card.ports.count} ports"   for port in card.ports     puts "shelf #{shelf.id} - card #{card.id} - port #{port.id}"   end end

4

I tried to do shelf.cards.count and I get an error saying it cannot find shelf.id in the cards table.