rails extract data from simple json response

Question

I need to extract some data from a JSON response i'm serving up from curb.

Previously I wasn't calling symbolize_keys, but i thought that would make my attempt work.

The controller action:

http = Curl.get("http://api.foobar.com/thing/thing_name/catalog_items.json?per_page=1&page=1") do|http|
  http.headers['X-Api-Key'] = 'georgeBushSucks'
end
pre_keys =  http.body_str
@foobar = ActiveSupport::JSON.decode(pre_keys).symbolize_keys

In the view (getting undefined method `current_price' )

@foobar.current_price

I also tried @foobar.data[0]['current_price'] with the same result

JSON response from action:

{
    "data": {
        "catalog_items": [
            {
                "current_price": "9999.0",
                "close_date": "2013-05-14T16:08:00-04:00",
                "open_date": "2013-04-24T11:00:00-04:00",
                "stuff_count": 82,
                "minimum_price": "590000.0",
                "id": 337478,
                "estimated_price": "50000.0",
                "name": "This is a really cool name",
                "current_winner_id": 696969,
                "images": [
                    {
                        "thumb_url": "http://foobar.com/images/93695/thumb.png?1365714300",
                        "detail_url": "http://foobar.com/images/93695/detail.png?1365714300",
                        "position": 1
                    },
                    {
                        "thumb_url": "http://foobar.com/images/95090/thumb.jpg?1366813823",
                        "detail_url": "http://foobar.com/images/95090/detail.jpg?1366813823",
                        "position": 2
                    }
                ]
            }
        ]
    },
    "pagination": {
        "per_page": 1,
        "page": 1,
        "total_pages": 131,
        "total_objects": 131
    }
}

Answer 1

Please note that accessing hash's element in Rails work in models. To use it on hash, you have to use OpenStruct object. It's part of standard library in rails. Considering, @foobar has decoded JSON as you have.

obj = OpenStruct.new(@foobar)
obj.data
#=> Hash

But, note that, obj.data.catalog_items willn't work, because that is an hash, and again not an OpenStruct object. To aid this, we have recursive-open-struct, which will do the job for you.

Alternative solution [1]:

@foobar[:data]['catalog_items'].first['current_price']

But, ugly.

Alternative solution [2]:

Open Hash class, use method_missing ability as :

class Hash
  def method_missing(key)
    self[key.to_s]
  end
end

Hope it helps. :)