parse json to object ruby

Question

I looked into different resources and still get confused on how to parse a json format to a custom object, for example

class Resident
  attr_accessor :phone, :addr

  def initialize(phone, addr)
      @phone = phone
      @addr = addr
  end
end

and JSON file

{
  "Resident": [
    {
      "phone": "12345",
      "addr":  "xxxxx"
    }, {
      "phone": "12345",
      "addr": "xxxxx"
    }, {
      "phone": "12345",
      "addr": "xxxxx"
    }
  ]
}

what's the correct way to parse the json file into a array of 3 Resident object?

Parse this JSON into a ruby hash, then walk that hash and create Resident objects. — Sergio Tulentsev
– Sergio Tulentsev, Commented Oct 4, 2012 at 8:21
@SergioTulentsev Thanks I got that part but how to fit in new object? Is it using class_variable_defined or something else? — flint_stone
– flint_stone, Commented Oct 4, 2012 at 8:35
Just a note to say that you need to remove the trailing comma after the "xxxxx" , else JSON will complain. — Anand Shah
– Anand Shah, Commented Oct 4, 2012 at 8:42

JGutierrezC · Accepted Answer · 2015-09-09 02:48:19Z

111

Today i was looking for something that converts json to an object, and this works like a charm:

person = JSON.parse(json_string, object_class: OpenStruct)

This way you could do person.education.school or person[0].education.school if the response is an array

I'm leaving it here because might be useful for someone

answered Sep 9, 2015 at 2:48

JGutierrezC

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2 Comments

Alu Over a year ago

imho the best way to do it.

Dave Newton Over a year ago

Convenient, but not a custom object.

KARASZI István · Accepted Answer · 2013-09-26 12:18:07Z

42

The following code is more simple:

require 'json'

data = JSON.parse(json_data)
residents = data['Resident'].map { |rd| Resident.new(rd['phone'], rd['addr']) }

edited Sep 26, 2013 at 12:18

answered Oct 4, 2012 at 8:55

KARASZI István

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Comments

Dragas · Accepted Answer · 2017-07-21 06:43:30Z

13

If you're using ActiveModel::Serializers::JSON you can just call from_json(json) and your object will be mapped with those values.

class Person
  include ActiveModel::Serializers::JSON

  attr_accessor :name, :age, :awesome

  def attributes=(hash)
    hash.each do |key, value|
      send("#{key}=", value)
    end
  end

  def attributes
    instance_values
  end
end

json = {name: 'bob', age: 22, awesome: true}.to_json
person = Person.new
person.from_json(json) # => #<Person:0x007fec5e7a0088 @age=22, @awesome=true, @name="bob">
person.name # => "bob"
person.age # => 22
person.awesome # => true

answered Jul 21, 2017 at 6:43

Dragas

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Comments

random · Accepted Answer · 2013-07-07 14:17:32Z

4

require 'json'

class Resident
    attr_accessor :phone, :addr

    def initialize(phone, addr)
        @phone = phone
        @addr = addr
    end
end

s = '{"Resident":[{"phone":"12345","addr":"xxxxx"},{"phone":"12345","addr":"xxxxx"},{"phone":"12345","addr":"xxxxx"}]}'

j = JSON.parse(s)

objects = j['Resident'].inject([]) { |o,d| o << Resident.new( d['phone'], d['addr'] ) }

p objects[0].phone
"12345"

edited Jul 7, 2013 at 14:17

random

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answered Oct 4, 2012 at 8:35

user904990

2 Comments

KARASZI István Over a year ago

That's not bad, but you could use the Enumerable#map instead of each.

KARASZI István Over a year ago

I added my idea as an answer.

ka8725 · Accepted Answer · 2016-01-18 02:57:04Z

3

We recently released a Ruby library static_struct that solves the issue. Check it out.

answered Jan 18, 2016 at 2:57

ka8725

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