Can't access JSON data returned from backend

Question

I make an AJAX request and I get back a response saved to a data variable.

My controller:

def retrieve
  data = params[:data]
  @question = Question.find_by(id: params[:question_id])
  @choices = @question.choices
  results = []
  for d in data
    if Choice.find_by(id: d).correct
      results << d
    end
  end

  respond_to do |format|
    format.json {
      render json: {
        choices: @choices.to_json(only: [:id,:correct]),
        results: results,
        message: "success"
        }
      }
  end
end

The response:

Object {choices: "[{"id":1,"correct":true},{"id":2,"correct":false}]", results: Array[1], message: "success"}

I'm getting value undefined where there should be a value.

data.choices[0].id -> returns undefined

the json response not recognizing the value of choices as array instead it recongnize it as string. I think you should try the following use as_json instead of to_json — Moustafa Sallam
– Moustafa Sallam, Commented Sep 15, 2015 at 12:51
@MoustafaSallam - Sorry, did not read those comments before posting the answer. Please post an answer and I will delete mine. — BroiSatse
– BroiSatse, Commented Sep 15, 2015 at 12:59
@BroiSatse not a big deal, keep your answer. it doesn't matter — Moustafa Sallam
– Moustafa Sallam, Commented Sep 15, 2015 at 13:01

Moustafa Sallam · Accepted Answer · 2015-09-15 13:11:14Z

3

Use as_json instead of to_json

Your code should be

@choices.as_json(only: [:id,:correct])

instead of

@choices.to_json(only: [:id,:correct])

For further information about difference between as_json and to_json please checkout this link

Simply as_json works better with complex datatypes like activerecord objects

answered Sep 15, 2015 at 13:11

Moustafa Sallam

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1 Comment

BroiSatse Over a year ago

To add a little bit more - to_json uses as_json internally. The main difference between those two methods is that former returns a json string, while latter returns a hash.

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