Ruby - parsing JSON coming via URL

Question

I'm sending a JSON object to ruby with javascript. But I cannot parse it in there. I tried following stuff but no luck. Also I've been searching around for while now, but I couldn't find anything helpful.

Note that I'm very new ruby.

My trials:

def initialize(game_conf_json)        
    parsed_conf = JSON.parse(conf_json)
    @param1 = parsed_conf['name'][0]
    @param2 = parsed_conf['surname'][0]

    =begin
    I also tried this:
    @param1 = parsed_conf['name']
    @param2 = parsed_conf['surname']

    But no matter what other things I try, I'm getting the following error:
    "21:in `[]': can't convert String into Integer (TypeError)"

    OR

    "can't convert Array into String (TypeError), "

    =end


    File.open("some_direc/conf.json", "w") do |f|
        f.write(game_conf_json)
    end

end

I create the json in javascript like this:

var json_of_form_vars = {};
json_of_form_vars.name = name_val;
json_of_form_vars.surname = surname_val;

And send it this way:

$.ajax({
    url: "../fundament/dispatch.rb/",
    type: "post",
    dataType: "json",
    data: "conf="+json_of_form_vars,
    .....

How can I solve this problem? Is there any proper tutorial for this of problem?

UPDATE1 (After suggestions): I used JSON.stringify and then passed the object to ruby. And then I finally able to print the object in ruby. It's listed below:

{"name": "METIN", "surname": "EMENULLAHI"}

The method .class claims that it is an array. But I cannot access data with classical ways, like:

array['name']

the error is:

can't convert String into Integer

And when I try to pass it to the JSON.parse in ruby, it gives me the following error:

can't convert Array into String

So I used JSON.parse(conf_array.to_json), but again when accessing the data it gives the same error like arrays:

can't convert String into Integer

What should be done now?

UPDATE2 Here is my cgi handler which passes the URL parameters to appropriate places:

cgi_req = CGI::new
puts cgi_req.header

params_from_request = cgi_req.params

logger.error "#{params_from_request}"

action_todo = params_from_request['action'][0].chomp

base = Base.new

if action_todo.eql?('create')
    conf_json = params_from_request['conf']
    # This line prints the json like this: {"name": "SOME_NAME", "surname": "SOME_SURNAME"}
    logger.error "#{conf_json}"
    base.create_ident(conf_json) 
end

And in Base class:

def create_ident(conf_json)
   require 'src/IdentityCreation'
   iden_create = IdentityCreation.new(conf_json)
end

IdentityCreation's constructor is listed above.

UPDATE3:

Ok, I now get at least something out of the array. But when I access a key, it displays the key itself:

parsed_conf = JSON.parse(conf_json.to_json)
@param1 = parsed_conf[0]['name']
@param2 = parsed_conf[0]['surname']

# At this point when I print the @param1, it gives me "name"(the key), not "SOME_NAME"(the value).

You'll have to include a sample of the JSON you're trying to parse. — fmendez
– fmendez, Commented Apr 2, 2013 at 11:28
Your post data looks suspicious to me - a mixture of form encoded parameters and json data. When you do "conf=" + json_of_form_vars it's going to try and convert that javascript object to a string, which will likely yield something unhelpful like [Object object]. You need to use JSON.stringify to convert it to json. — Frederick Cheung
– Frederick Cheung, Commented Apr 2, 2013 at 11:55
@FrederickCheung, you should post that as an answer. That's what the OP is doing wrong. — Alex D
– Alex D, Commented Apr 2, 2013 at 12:25

peter · Accepted Answer · 2013-04-02 10:58:33Z

1

Here an example of parsing a JSON string. If you still have problems, publish the generated JSON so that we can try it.

require 'json'
require 'ap'

string = %{
  {"configurations" : [ 
  { "drinks" : [
          {"menus" : [
            { "hot" : [
              {"id":15,"unit":"0.33", "price":"1", "currency":"Euro", "position": 4},
              {"id":15,"unit":"0.33", "price":"1", "currency":"Euro", "position": 6}
            ] },

            { "cold" : [
          {"id":15,"unit":"0.33", "price":"1", "currency":"Euro", "position": 4},
              {"id":15,"unit":"0.33", "price":"1", "currency":"Euro", "position": 6}
             ] },

            { "terminals" : { "id" : 4, "id": 6, "id": 7 } }, 

            { "keys" : { "debit" : "on", "credit": "off" }  }

          ] }
  ] } ] } 
}

hash = JSON.parse(string)
ap hash

gives

{
    "configurations" => [
        [0] {
            "drinks" => [
                [0] {
                    "menus" => [
                        [0] {
                            "hot" => [
                                [0] {
                                          "id" => 15,
                                        "unit" => "0.33",
                                       "price" => "1",
                                    "currency" => "Euro",
                                    "position" => 4
                                },

etc..

answered Apr 2, 2013 at 10:58

peter

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1 Comment

0xmtn Over a year ago

When I try to print the JSON string coming from javascript in ruby, it prints only [Object object]. And the .class, also gives the same output. So how can I dump this string in ruby. Obviously, it is not a plain string. Also I used pretty print, but no luck either.

Frederick Cheung · Accepted Answer · 2013-04-02 13:00:47Z

At the moment you're not actually posting json. You're attemping to post json wrapped inside form encoded parameters. In addition, when you do

"conf=" + json_of_form_vars

javascript will convert json_of_form_vars to a string for you but that conversion isn't the same as dumping to JSON. Javascript default string conversions are pretty useless for objects, so you'll need to use JSON.stringify to get actual json.

Since you're composing the body as a string literal you'll also need to escape any special characters that aren't allowed (or have special meaning) in this context. It's usually easier to let jquery do the heavy lifting, with something like

$.ajax({
    url: "../fundament/dispatch.rb/",
    type: "post",
    dataType: "json",
    data: {conf: JSON.stringify(json_of_form_vars)}

0xmtn · Accepted Answer · 2013-04-03 11:36:35Z

0

I solved it finally. Using all the suggestions made under this post and also my irb experiences with hashes, arrays, json and etc.

So instead of converting my object (conf_json) to json (with to_json), I passed it to JSON.parse as a string like below:

parsed_conf = JSON.parse(%{#{conf_json}})

It seems kind of weird to me, because when try to pass it to function like below, I got the error of can't convert Array into String.

parsed_conf = JSON.parse(conf_json)

But it is working like a charm right now.

answered Apr 3, 2013 at 11:36

0xmtn

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