Filter through nested JSON object and obtain JSON with specific keys, using Ruby

Question

I currently have a nested JSON object which resembles

{
"People": [
    {
        "Name": "James",
        "Age": "18",
        "Gender": "Male",
        "Sports": []
    },
    {
        "Name": "Sarah",
        "Age": "19",
        "Gender": "Female",
        "Sports": [
            "Soccer",
            "Basketball",
            "Football"
        ]
    }
] 
}

Being new to Ruby, I aim to filter throught the entire json and return only the json object/objects in which the "Sports" array has content. So in the above scenario I expect to obtain the object below as a final outcome:

    {
        "Name": "Sarah",
        "Age": "19",
        "Gender": "Female",
        "Sports": [
            "Soccer",
            "Basketball",
            "Football"
        ]
    }

Will I have to initiate a new method to perform such an act? Or would using regular ruby calls work in this case?

dvxam · Accepted Answer · 2016-03-29 07:32:35Z

2

Although @philipyoo answer is right, it miss an explanation on how to "filter" the parsed JSON. If you are new to ruby, take a look at Array#keep_if : http://ruby-doc.org/core-2.2.0/Array.html#method-i-keep_if

require 'json'

people = JSON.parse("{long JSON data ... }")
people_with_sports = people.fetch('People', []).keep_if do |person|
  !person.fetch('Sports', []).empty?
end

answered Mar 29, 2016 at 7:32

dvxam

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3 Comments

Iqen Over a year ago

This is just along the lines of what I'm looking for. However running this seems to retrieve a "undefined method 'fetch'" error. I've tried using 'map' or 'each do', and i get the same 'undefined method' error

dvxam Over a year ago

Can you tell me the exact error? "undefined method error for XXX class". What is the XXX class? Can you give me more information about the content of people variable? My guess is that it is not a Hash. Maybe due to the JSON content.

Iqen Over a year ago

Never mind. It was an error on my end. Your answer was exactly what I was looking for.

philip yoo · Accepted Answer · 2016-03-29 01:24:01Z

2

If you're getting a JSON object from a request, you want to parse it and then you can traverse the hash and arrays to find the information you need. See http://ruby-doc.org/stdlib-2.0.0/libdoc/json/rdoc/JSON.html

In your case, something like this:

require 'json'

parsed_json = JSON.parse('{"People": [ ... ]}')

parsed_json["People"].each do |person|
  puts person if person["name"] == "Sarah"
end

answered Mar 29, 2016 at 1:24

philip yoo

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