在Ruby中获取JSON和数组之间的通用元素

Question

I now have a JSON string:

[{"id":1,"name":"good","created_at":"2014-07-28T19:45:50.440Z","updated_at":"2014-07-28T19:45:50.440Z"},{"id":2,"name":"better","created_at":"2014-07-28T19:45:50.447Z","updated_at":"2014-07-28T19:45:50.447Z"},{"id":3,"name":"best","created_at":"2014-07-28T19:45:50.449Z","updated_at":"2014-07-28T19:45:50.449Z"}]

And I have an array:

id = ["1", "3"]

I want to check for the common IDs and print the associated name. For the above example I want my output to be:

 ["good","best"]

I want the output preferably to be an array. Is there a easy way to do this? I have been writing too much code to get this done and feel it should be easily done. Any suggestions?

Answer 1

# initiate json string
json = %q([{"id":1,"name":"good","created_at":"2014-07-28T19:45:50.440Z","updated_at":"2014-07-28T19:45:50.440Z"},{"id":2,"name":"better","created_at":"2014-07-28T19:45:50.447Z","updated_at":"2014-07-28T19:45:50.447Z"},{"id":3,"name":"best","created_at":"2014-07-28T19:45:50.449Z","updated_at":"2014-07-28T19:45:50.449Z"}])

ids = ["1", "3"]

JSON.parse(json).select{|x| ids.include? x["id"].to_s}.map{|x| x["name"]}
#=> ["good", "best"]  

Answer 2

require 'json'

def pluck(json, ids)
  json_parsed = JSON.parse(json)

  json_parsed.select do |obj|
    ids.include?(obj['id'])
  end
  .map do |obj|
    obj['name']
  end
end

# usage
json = '[{"id":1,"name":"good","created_at":"2014-07-28T19:45:50.440Z","updated_at":"2014-07-28T19:45:50.440Z"},{"id":2,"name":"better","created_at":"2014-07-28T19:45:50.447Z","updated_at":"2014-07-28T19:45:50.447Z"},{"id":3,"name":"best","created_at":"2014-07-28T19:45:50.449Z","updated_at":"2014-07-28T19:45:50.449Z"}]'
ids = [1, 3]
pluck(json, ids)

Answer 3

in you controller can do this:

def  method_name

  render json: Model.pluck(:name).to_json

end