Filter JSON array by value with Ruby

Question

I have a JSON array that looks something like this.

[
 {"name":"Idaho","state":{"id":1,"name":"A"}},
 {"name":"Wyoming","state":{"id":1,"name":"A"}},
 {"name":"Montana","state":{"id":2,"name":"B"}},
 {"name":"South Dakota","state":{"id":1,"name":"B"}}
]

How would I use Ruby to only show the value of A?

I don't think sort_by will be the answer because what I have below just sorts them alphabetically. I want to completely exclude all results from B.

.sort_by { |a| [a.state.name] }

What would be the most efficient way to do this in a .rb file?

I solved my own question. This is how I achieved what I wanted.

.select { |a| a.state.name == "A" }

a.state.name is how you'd do it in JavaScript, but in Ruby this is a['state']['name']. — tadman
– tadman, Commented Sep 4, 2014 at 20:40
Alternatively, str.scan(/[A-Z][a-zA-Z\s]+(?=.+:\"A\".+?$)/) => ["Idaho", "Wyoming"]. — Cary Swoveland
– Cary Swoveland, Commented Sep 5, 2014 at 0:44

Todd A. Jacobs · Accepted Answer · 2014-09-04 20:48:33Z

5

require 'json'

json = <<'JSON_STRING'
[
 {"name":"Idaho","state":{"id":1,"name":"A"}},
 {"name":"Wyoming","state":{"id":1,"name":"A"}},
 {"name":"Montana","state":{"id":2,"name":"B"}},
 {"name":"South Dakota","state":{"id":1,"name":"B"}}
]
JSON_STRING

data = JSON.parse json

data.map(&:values).select { |state, values| values["name"] == ?A }
#=> [["Idaho", {"id"=>1, "name"=>"A"}], ["Wyoming", {"id"=>1, "name"=>"A"}]]

data.map(&:values).select { |state, values| values["name"] == ?A }.map(&:first)
#=> ["Idaho", "Wyoming"]

answered Sep 4, 2014 at 20:48

Todd A. Jacobs

85.1k15 gold badges147 silver badges209 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

7stud · Accepted Answer · 2014-09-04 21:00:59Z

2

require 'json'

arr = JSON.parse <<END_OF_JSON
[
 {"name":"Idaho","state":{"id":1,"name":"A"}},
 {"name":"Wyoming","state":{"id":1,"name":"A"}},
 {"name":"Montana","state":{"id":2,"name":"B"}},
 {"name":"South Dakota","state":{"id":1,"name":"B"}}
]
END_OF_JSON

results = []

arr.each do |hash|
  results << hash["name"] if hash["state"]["name"] == "A"
end

p results

--output:--
["Idaho", "Wyoming"]

edited Sep 4, 2014 at 21:00

answered Sep 4, 2014 at 20:50

7stud

48.8k14 gold badges107 silver badges137 bronze badges

Comments

Nick Gallimore · Accepted Answer · 2019-04-15 00:59:52Z

0

Incorrect:

.select { |a| a.state.name == "A" }

Correct way:

.select { |a| a['state']['name'] == 'A' }

answered Apr 15, 2019 at 0:59

Nick Gallimore

1,30315 silver badges37 bronze badges

Collectives™ on Stack Overflow

Filter JSON array by value with Ruby

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related