Check existence of JSON nested attribute

Question

I need to test whether a nested attribute exists in a JSON object before doing something with it. How can I accomplish this?

I know I can test one level at the time but this seems crazy when is a complex data structure. (Ruby code)

#!/usr/bin/ruby

require 'json'

json_string = '
    {
        "name" : "Matias",
        "age" : 31,
        "team" : {
            "name" : "Some team",
            "size" : 3
        }

    }
'

json_obj = JSON.parse(json_string)


puts json_obj['name'] if json_obj['fake']['name']

rewritten · Accepted Answer · 2018-10-08 21:58:36Z

3

You can use Hash#dig which will just return nil as soon as a key is not found:

json_obj.dig('fake', 'name')

I assume you are on a recent version of ruby (>= 2.3).

Documentation for dig here: http://ruby-doc.org/core-2.5.1/Hash.html#method-i-dig

edited Oct 8, 2018 at 21:58

answered Oct 8, 2018 at 21:35

rewritten

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rewritten Over a year ago

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