How do I build this JSON object in ruby?

Question

I need to bring an array of ruby objects in JSON. I will need to find the item in the JSON object by id, so I think it is best that the id is the key of each object. This structure makes the most sense to me:

{
    "1":   {"attr1": "val1", "attr2": "val2"},
    "2":   {"attr1": "val1", "attr2": "val2"},
    "3":   {"attr1": "val1", "attr2": "val2"}
}

That way I can easily call into the json object like console.log(json_obj[id].attr1)

The issue is that I am not quite sure how to build this in ruby. This is as far as I have gotten:

# in ruby
@book_types = []
BookType.all.each do |bt|
   @book_types << {bt.id => {:attr => bt.attr}}
end
@book_types = @book_types.to_json

// In JS
var bookTypes = JSON.parse('<%=raw @book_types %>');

2 questions: How can I build this in ruby? Is there a better way to accomplish what I am doing?

Also just a note that I am building this on the Rails framework

Thanks!

Answer 1

Assuming BookType is an ActiveRecord class, you can just do this:

BookType.all(:select => "attr1, attr2").to_json

...where "attr1, attr2" is a list of the attributes you want to include in your JSON.

If you want the ids as keys, you can do this instead:

BookType.all.inject({}) { |hsh, bt|
  hsh[bt.id] = { "attr1" => bt.attr1, "attr2" => bt.attr2 }
  hsh
}.to_json