Adding values to array hash ruby at a specific position

Question

I have a hash response object which looks like this:

jsonResponse = {:json=>{"reply"=>[{"person"=>"abc", "roll_no"=>"1234", "location"=>"loc1", "score"=>"1"}, {"person"=>"def", "roll_no"=>"1235", "location"=>"loc2", "score"=>"2"},{"person"=>"fgh", "roll_no"=>"1236", "location"=>"loc3", "score"=>"3"}]}, :status=>200}

I have to add one key value pair at a specific position to each of these reply array objects, so that the response transforms to something like this, to make it simpler for now, lets try adding a samke key value pair at a particular position:

jsonResponse = {:json=>{"reply"=>[{"person"=>"abc", "roll_no"=>"1234","location"=>"loc1", "new_value => "new_result", "score"=>"1"}, {"person"=>"def", "roll_no"=>"1235", "location"=>"loc2","new_value => "new_result", "score"=>"2"},{"person"=>"fgh", "roll_no"=>"1236", "location"=>"loc3", "new_value => "new_result", "score"=>"3"}]}, :status=>200}

This is what I have tried,I run.each through jsonResponse:

jsonResponse[:json]['reply'].each do |object|
               objectArray = object.to_a
               insert_at = objectArray.index(objectArray.assoc('score'))
               object = Hash[objectArray.insert(insert_at, ['new_value','new_result'])]
               print("\n\nTest\n\n")
               print object
      end
    print("\n\nFinal Response\n\n")
    print jsonResponse

The object which i am printing has the desired response but it does not get updated in the jsonResponse

This is the output of the above code snippet:

Test

{"person"=>"abc", "roll_no"=>"1234", "location"=>"loc1", "new_value"=>"new_result", "score"=>"1"}

Test

{"person"=>"def", "roll_no"=>"1235", "location"=>"loc2", "new_value"=>"new_result", "score"=>"2"}

Test

{"person"=>"fgh", "roll_no"=>"1236", "location"=>"loc3", "new_value"=>"new_result", "score"=>"3"}

Final Response

{:json=>{"reply"=>[{"person"=>"abc", "roll_no"=>"1234", "location"=>"loc1", "score"=>"1"}, {"person"=>"def", "roll_no"=>"1235", "location"=>"loc2", "score"=>"2"}, {"person"=>"fgh", "roll_no"=>"1236", "location"=>"loc3", "score"=>"3"}]}, :status=>200}

Q2. Also as you can see from the code snippet the insert_at logic works in a way that it adds before the position we specify, for eg it adds before score key , is there a logic which i can write which adds to the position after the specified key and not before?

Appreciate the efforts by everyone

Answer 1

We are given three objects.

jsonResponse = {
  :json=>{
    "reply"=>[
      {"person"=>"abc", "roll_no"=>"1234", "location"=>"loc1", "score"=>"1"},
      {"person"=>"def", "roll_no"=>"1235", "location"=>"loc2", "score"=>"2"}, 
      {"person"=>"fgh", "roll_no"=>"1236", "location"=>"loc3", "score"=>"3"}
    ]
  },
  :status=>200
}

key_value_pair_to_add = { 'new_value'=>'new_result' }
key_to_precede = 'location'

We then modify jsonResponse as follows.

keys_to_shift = jsonResponse[:json]['reply'][0].keys.
  drop_while { |k| k != key_to_precede }        
  #=> ["location", "score"]
jsonResponse[:json]['reply'].each do |h| 
  h.update('new_value'=>'new_result')
  keys_to_shift.each { |k| h.update(k=>h.delete(k)) }
end

jsonResponse
  #=> {
  #     :json=>{
  #       "reply"=>[
  #         {"person"=>"abc", "roll_no"=>"1234", "new_value"=>"new_result",
  #          "location"=>"loc1", "score"=>"1"},
  #         {"person"=>"def", "roll_no"=>"1235", "new_value"=>"new_result",
  #          "location"=>"loc2", "score"=>"2"},
  #         {"person"=>"fgh", "roll_no"=>"1236", "new_value"=>"new_result",
  #          "location"=>"loc3", "score"=>"3"}
  #       ]
  #     },
  #     :status=>200
  #   }

See Hash#update (aka merge! ) and Hash#delete .

h.delete('location')

removes the key-value pair 'location'=>'locX' from h and returns locX , after which

h.update('location'=>'locX')

returns that key-value pair to the end of the hash. This is repeated for each key in keys_to_shift .

Answer 2

Give a simple example:

# define order 
order = [:first, :second, :third]
# the hash you want to order by
json = { :third=>"3", :second=>2, :first=>1 }

result = json.sort_by { |k, _| order.index(k) }.to_h

then result will be {:first=>1, :second=>2, :third=>"3"}