20

I use 'gem json' and need load JSON data from some url, for example:

"http://locallhost:3000/qwerty/give_json.json" with

{"one":"Omg","two":125,"three":"Hu"}

I have rails app

class QwertyController < ApplicationController
    require 'json'

    def get_json
        source = "http://localhost:3000/qwerty/give_json.json"
        @data = JSON.parse(JSON.load(source))
    end
end

I get error 

JSON::ParserError in QwertyController#get_json
795: unexpected token at 'http://localhost:3000/qwerty/give_json.json'

In string: @data = JSON.parse(JSON.load(source))

What is the matter? How can I get JSON data and parse it? I try @data["one"] ...

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5
  • Looks like you have invalid JSON in the source Commented Sep 2, 2013 at 22:55
  • No it's not. I created a rails app, which generate JSON answer on port 3000 (localhost:3000/qwerty/give_json.json). And second app, which try to get JSON data on port 3001 (localhost:3001/qwerty/get_json) Commented Sep 2, 2013 at 22:59
  • 2
    What version of ruby are you using? you don't need to require json in newer versions of rails and ruby... Commented Sep 2, 2013 at 23:00
  • alexkd@Active-pc:~$ ruby -v ruby 1.9.3p448 (2013-06-27 revision 41675) [i686-linux] alexkd@Active-pc:~$ rails -v Rails 4.0.0 Commented Sep 2, 2013 at 23:03
  • Yes you do have invalid JSON. YOu are calling JSON.load on a URL string, not a JSON object. That is invalid JSON. JSON.load doesnt read data from a url, you are just passing the string in Commented Sep 2, 2013 at 23:10

4 Answers 4

Reset to default
53

JSON.load takes a source that is a String or IO object according to the documentation

http://www.ruby-doc.org/stdlib-1.9.3/libdoc/json/rdoc/JSON.html#method-i-load

[17] pry(main)> {hello: "World"}.to_json
=> "{\"hello\":\"World\"}"
[18] pry(main)> JSON.load(_)
=> {"hello"=>"World"}

You're giving it a String that is a URL and that's why you're getting an error. You can use open-uri to fetch the data from the URL to then be parsed by JSON like so...

[22] pry(main)> require 'open-uri'
=> false
[23] pry(main)> JSON.load(URI.open("https://api.github.com"))
=> {"current_user_url"=>"https://api.github.com/user",
 "authorizations_url"=>"https://api.github.com/authorizations",
 "emails_url"=>"https://api.github.com/user/emails",
 "emojis_url"=>"https://api.github.com/emojis",
 "events_url"=>"https://api.github.com/events",
 "feeds_url"=>"https://api.github.com/feeds",
 "following_url"=>"https://api.github.com/user/following{/target}",
 "gists_url"=>"https://api.github.com/gists{/gist_id}",
 "hub_url"=>"https://api.github.com/hub"}

NOTE

URI.open returns a StringIO object which responds to read returning the JSON data. JSON.load turns the data into a hash to be used.

To parse the JSON string you can either use JSON.load or JSON.parse

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3 Comments

that is a really good solution!! I had to explicitly call URI.open, otherwise it gave me a No such file or directory error, but other then that, I found this to be the most elegant solution.
@wnm same for me. If it's like that for everyone we should probably edit the answer to include it. I have no idea if it's the way for everyone
It's likely that the open call may have worked in the past but now it's invoking Kernel#call which would return the error you're seeing now. I've updated the solution to include URI as part of the call
18

You could use net/http library like below:

   require 'net/http'
   source = 'http://localhost:3000/qwerty/give_json.json'
   resp = Net::HTTP.get_response(URI.parse(source))
   data = resp.body
   result = JSON.parse(data)

Or the gem http party:

require 'httparty'

response = HTTParty.get('http://localhost:3000/qwerty/give_json.json')
json = JSON.parse(response.body)
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3

By default, httparty already includes the JSON library within httparty.rb.
This means that the call to require 'json' is unnecessary.

Thanks for providing these examples!

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3

You could use JSON and net/http lib.. which is below:

require 'net/http'
require 'json'

url = "https://api.url/"
uri = URI(url)
response = Net::HTTP.get(uri)
data = JSON.parse(response)
objs.each do |data|
  title = data["title"]
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