How can I store nested json data in Rails? - ruby-on-rails

Question

I have 3 models:
class Depot < ActiveRecord::Base
has_many :car_amounts
has_many :cars, :through => :car_amounts
end
class CarAmount < ActiveRecord::Base
belongs_to :depot
belongs_to :car
end
class Car < ActiveRecord::Base
has_many :car_amounts
has_many :depots, :through => :car_amounts
end
What is the best way to store json paramers, which contains depot, amounts and cars data. Something like this:
{
"Depots": {
"title": "Dealer1"
},
"Amounts": [
{
"amount": "1"
"car": [
{
"Type": "supercar1"
}
]
},
{
"amount": "5"
"car": [
{
"Type": "supercar2"
}
]
},
]
}

Answer 1

I am a little unclear what your question is, but I think you might be looking for accepts_nested_attributes_for. The documentation can be found here http://api.rubyonrails.org/classes/ActiveRecord/NestedAttributes/ClassMethods.html. From the documentation:
Nested attributes allow you to save attributes on associated records through the parent.
As an example, you could add accepts_nested_attributes_for :cars in you Depots model. While it wouldn't quite work with the JSON you've shown above, it works well with the general idea.
If this isn't quite your question then please comment and I will clarify.

Answer 2

If this data needs to be in you your database then I would 'seed' the data and import it into your database. You can create a file db/seed.rb and lets say I want to import students into my database. I have a student model already created/migrated. In my seed.rb I would do something like...
students = ActiveSupport::JSON.decode(File.read('db/students.json'))
students.each do |a|
Student.find_or_create_by_id_number(:id_number => a['id_number'], :username => a['username'], :first_name => a['first_name'], :last_name => a['last_name'])
end
...and my students.json looks like...
[
{"id_number": "00xx280","username": "jesxxne","first_name": "Jessie","last_name": "Lane","email": "jesxxane#xx.edu","phone_number": "602-321-6693","is_active": true ,"last_four": "1944" },
{"id_number": "11xx2","username": "jamxxacqua","first_name": "James","last_name": "Bevixxua","email": "jamesbxxacqua#xx.edu","phone_number": "828-400-5393","is_active": true ,"last_four": "5422" }
]
Now you can run rake db:seed to import this data. Good luck!