Sorting JSON data in Ruby

Question

I have following JSON structure:

 {
  "name": "MessageEnvelope",
  "type": "record",
  "fields": [
   {
      "name": "message",
      "type": 
        {
          "name": "Message",
          "type": "record",
           "fields": [
             ....
            ]
        }
   },
   {
      "name": "pipeline_system",
      "type": {
                 "type": "enum",
                 "name": "PipelineSystem",
                 "symbols": [ "enterprise", "backscoring", "compliance" ]
              }
    },
    {
      "name": "batch_id",
      "type": [ "null", "string" ]
    }
 ]
}

I am looking to sort the above JSON file as best as it could be. For example:

fields : [
  {
      "name": "batch_id",
      "type": [ "null", "string" ]
    }, 
  ...
  ...
  {
      "name": "pipeline_system",
      "type": {
                 "type": "enum",
                 "name": "PipelineSystem",
                 "symbols": [ "backscoring",  "compliance", "enterprise" ]
              }
    }

Like it sorts the internal arrays as well as hashes. I am trying to write following:

def sort(collection)
   if collection.is_a?(Hash)
    puts "Hash Object...."
    if(collection["type"]=="record")
      puts "record found...     Type = #{collection["fields"].class}";
      if collection["fields"].is_a?(Array)
        puts "fields type is array...."           #we can sort fields arrays on the basis of name
        collection["fields"].sort_by{|arrayCollectionElement| arrayCollectionElement["name"] } 
        arrayCollection = collection["fields"]    #this is array of hash...we can sort them on the basis of name..done above in sort by...
        puts "class  = #{arrayCollection.class}"
        puts "sorted fields:  #{arrayCollection}"
      end
    end   #else it is again a hash
  end
  collection
end

but it is not sorting the fields array on the basis of names.

Appreciate any possible help!

Aleksei Matiushkin · Accepted Answer · 2016-06-16 13:41:13Z

1

If I properly understood the requirements:

json = '...'

require 'json'
hash = JSON.parse json

# ⇓ let’s sort the array of fields inplace
hash['fields'].sort_by! { |o| o['name'] }

hash
#⇒ {
#  "fields" => [
#    [0] {
#      "name" => "batch_id",
#      "type" => [ "null", "string" ]
#    },
#    [1] {
#      "name" => "message",
#      "type" => {
#        "fields" => [],
#          "name" => "Message",
#          "type" => "record"
#      }
#    },
#    [2] {
#      "name" => "pipeline_system",
#      "type" => {
#           "name" => "PipelineSystem",
#        "symbols" => [ "enterprise", "backscoring", "compliance" ],
#           "type" => "enum"
#      }
#    }
#  ],
#    "name" => "MessageEnvelope",
#    "type" => "record"
# }

To sort all arrays inside, one might introduce a recursive function:

def sort_arrays hash
  hash.each do |_, v| 
    case v
    when Array then v.sort!
    when Hash then sort_arrays v
    end
  end
end

and call it on the topmost hash.

edited Jun 16, 2016 at 13:41

answered Jun 16, 2016 at 10:58

Aleksei Matiushkin

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3 Comments

scorix Over a year ago

Not only names, but also arrays inside the hash should be sorted. Such as "symbols": ["backscoring", "compliance", "enterprise" ]`

Ani Over a year ago

@scorix I could get array of hashes also like: "type" : [ "null" , { SOME_HASH}, {SOME_HASH} ] currently when Array then v.sort! will only sort the array of strings.

Ani Over a year ago

@scorix Can you please help me with link

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