Question

What is a good practice to create a JSON string of one object (object of class A) containing an array of objects (objects of class B)? I am particularly interessted in the implementation of class’s A to_json method.

Assuming class A looks as follows:

class A
  attr_accessor :items
  def initialize()
    @items = Array.new
  end
  def to_json(*a)
    ?SECRET OF THE DAY?
  end
end

and class B:

class B
  def to_json(*a)
    {"class B" => "class B"}.to_json(*a)
  end
end

The best solution I got so far is:

def to_json(*a)
  json = Array.new
  @items.each do |item|
    json << item.to_json(*a)
  end
  {"class A" => json}.to_json(*a)
end

Assuming there is only one item in array of an object of class A, the resulting JSON string looks as follows:

{“class A”:[“{\”class B\”:\”class B\”}”]}

I am sure we can do better?

Answer 1

I would do this instead

 def to_json(*a)
      {"class A" => @items}.to_json(*a)
 end

The problem with your approach is that your @items array contains strings, not objects. In that case your to_json will create an array of strings, not an array of objects.