How to count number of JSON objects in Ruby/Rails

Question

How can one in Ruby "generically" count the number of objects for JSONs in the below formats (rooted, unrooted)? By generically, I mean the elements may be different ("title" for instance by be called something else).

without root:

{
    [
      { "title": "Post 1", "body": "Hello!" },
      { "title": "Post 2", "body": "Goodbye!" }
    ]
}

root wrapped:

{
  "posts":
    [
      { "title": "Post 1", "body": "Hello!" },
      { "title": "Post 2", "body": "Goodbye!" }
    ]
}

BroiSatse · Accepted Answer · 2014-09-21 00:29:47Z

14

Firstly, without root code is not a valid json format. It would be without surrounding curly brackets, so I'm gona assume that's how it should be.

In first case:

json = '[
  { "title": "Post 1", "body": "Hello!" },
  { "title": "Post 2", "body": "Goodbye!" }
]'

require 'json'
ary = JSON.parse(json)
puts ary.count

The other case is not much different:

json = '{
  "posts":
    [
      { "title": "Post 1", "body": "Hello!" },
      { "title": "Post 2", "body": "Goodbye!" }
    ]
}')

require 'json'
hash = JSON.parse(json)
puts hash['posts'].count

answered Sep 21, 2014 at 0:29

BroiSatse

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1 Comment

user1322092 Over a year ago

Thanks for the quick response. Some frameworks - such as AngularJS - only consumes JSON without its root.

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