How can I use JavaScript to parse Ruby JSON string

Question

I'm trying to get the JSON object from a JSON outputted string from a Rails app. Currently in JavaScript I'm doing:

data = "<%= @chromosomes.html_safe %>";

However, since there are quotes at the beginning and end of the JSON object, it is not being rendered as a JSON object. Instead it is doing something like

 data = "[{"name":"YHet","organism_id":"4ea9b90e859723d3f7000037"}]"

Is there a way that I can remove the beginning and end quotes so that the object is treated as an array instead of a string?

I don't know what "html_safe" means exactly, but just as a note, it's not necessarily correct to use HTML-safe escapes ("<" for "<" etc) when you're dropping something directly into JavaScript source. — Pointy
– Pointy, Commented Apr 9, 2012 at 15:04
@Pointy in this case it probably is correct to use html_safe, since he probably wants [{"name":"<script src='badwebsite.com/bad.js'></script>","organism_id":"..."}] instead of [{"name":"<script src='badwebsite.com/bad.js'></script>","organism_id":"..."}]. — Peter C
– Peter C, Commented Apr 9, 2012 at 15:11
@alpha123 yes sometimes it's correct to use HTML escapes, but not always; for example, if the "organism_id" can contain HTML characters, it may be wrong to replace them if that string is purely intended to work inside JavaScript code and never be injected into the HTML. — Pointy
– Pointy, Commented Apr 9, 2012 at 15:21
@Pointy correct, although it looks like organism_id is a hash or GUID or something else not going to contain < or > or &, and name probably will be injected into HTML at some point. I'd say escape. — Peter C
– Peter C, Commented Apr 9, 2012 at 15:25

apneadiving · Accepted Answer · 2012-04-09 15:02:27Z

10

Why don't you do:

data = <%= @chromosomes.html_safe %>;

Sidenote:

I hope you do something like:

@chromosomes = [{ name: "YHet", organism_id: "foo" }].to_json

answered Apr 9, 2012 at 15:02

apneadiving

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4 Comments

Phillip Whisenhunt Over a year ago

I could, but JavaScript will not recognize the <%= :(. Thanks though.

Pointy Over a year ago

This is clearly the best thing to do; if it's already JSON it should just be dropped directly into the JavaScript source without additional quotes. @PhillipWhisenhunt it's not JavaScript that recognizes the <%= %> here; it's your server-side framework. If it works inside the double-quotes now, it'll work without them.

Peter C Over a year ago

@PhillipWhisenhunt um, that's the point. ERb goes in and processes everything starting with <% and ending with %> before the file gets sent to the client.

Phillip Whisenhunt Over a year ago

Correct. This is the best way to do it, removing the quotes fixed the issue. Whoops lol, @alpha123 had a major brain fart! Coding to early in the morning!

Two Seeds · Accepted Answer · 2012-04-09 15:04:33Z

1

If you are using jQuery you can do the following

var data = jQuery.parseJSON('[{"name":"YHet","organism_id":"4ea9b90e859723d3f7000037"}]');

answered Apr 9, 2012 at 15:04

Two Seeds

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Comments

Hauleth · Accepted Answer · 2012-04-09 15:02:19Z

0

Use JSON object that is included in most of browsers or if you are using jQuery use $.jsonParse method that try to use JSON object if defined otherwise parse using eval or some safer way.

answered Apr 9, 2012 at 15:02

Hauleth

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Comments

ferdynator · Accepted Answer · 2014-04-04 12:46:41Z

0

On controller

@my_var = MyObj.find_by_id(4).to_json

On page in haml way.

var my_json = $.parseJSON("#{j @my_var}"); //used JQuery to parser JSON string

edited Apr 4, 2014 at 12:46

ferdynator

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answered Apr 4, 2014 at 12:26

Joan

1

Comments

pertz · Accepted Answer · 2012-04-09 15:00:46Z

-1

Use eval:

var dataObject = eval('(' + dataString + ')');

answered Apr 9, 2012 at 15:00

pertz

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