RABL is a good add on to generate JSON output for the api projects.

Here is the situation to conquer.

	collection @groups, :object_root => false

	attributes :id, :name
	child :files do
	  extends "groups/_file"
	end

And next, the file partial template.

object @file

attributes :id

This will produce the output as

[
   {
      "id":"4f57bf67f85544e620000001",
      "name":"Some Group",
      "files":[
         {
            "file":{
               "id":"4f5aa3fef855441009000007"
            }
         }
      ]
   }
]

But we need the output something like this with out parent node for child nodes.

[
   {
      "id":"4f57bf67f85544e620000001",
      "name":"Some Group",
      "files":[
         {
            "id":"4f5aa3fef855441009000007"
         }
      ]
   }
]

There is solutions

  1. change is globally

Rabl.configure do |config|
  config.include_json_root = false
  config.include_child_root = false
end
  1. more control
#change this
child :files do
      extends 'groups/_file'
    end

#Into the code
node :files do |group|
      group.files.map do |file|
        partial 'groups/_file', object: file, root: false
      end
    end

# or
child :files, :object_root => false do
  extends 'groups/_file'
end

Note : if we and to change the behaviour of one element.


object @budget_product_promo
attributes :id,
           :name,
           node(:amount){|o|o.amount.to_f},
           :promo_sym,
           :promo_cycle_type,
           :budget_product_id

Finally here is some good read for the eagerload in rails.

rails4-preloading