Encode a Ruby string to a JSON string

Question

The json gem does not allow for directly encoding strings to their JSON representation. I tentatively ported this PHP code:

$text = json_encode($string);

to this Ruby:

text = string.inspect

and it seemed to do the job but for some reason if the string itself contains a literal string (it's actually JS code) with newlines, these newlines \n will stay as-is \n, not be encoded to \\n. I can understand if this is the correct behaviour of #inspect, but...

How does one encode a string value to its JSON representation in Ruby?

John · Accepted Answer · 2013-06-27 02:32:15Z

25

This works with the stock 1.9.3+ standard library JSON:

require 'json'
JSON.generate('foo', quirks_mode: true) # => "\"foo\""

Without quirks_mode: true, you get the ridiculous "JSON::GeneratorError: only generation of JSON objects or arrays allowed".

answered Jun 27, 2013 at 2:32

John

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Thai · Accepted Answer · 2014-10-10 18:08:22Z

20

As of Ruby 2.1, you can

require 'json'

'hello'.to_json

answered Oct 10, 2014 at 18:08

Thai

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Aleksei Matiushkin · Accepted Answer · 2013-02-17 03:19:38Z

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There are a myriad of JSON gems for Ruby, some pure Ruby some C-based for better performance.

Here is one that offers both pure-Ruby and C: http://flori.github.com/json/

And then its essentially:

require 'json'
JSON.encode(something)

A popular JSON encoder/decoder with native C-bindings for performance is Yajl: https://github.com/brianmario/yajl-ruby

UPD from @Stewart: JSON.encode is provided by rails as is object.to_json. For uses outside of rails use JSON.generate which is in ruby 1.9.3 std-lib. – Stewart

edited Feb 17, 2013 at 3:19

Aleksei Matiushkin

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answered Jul 21, 2011 at 23:23

Cody Caughlan

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4 Comments

Félix Saparelli Over a year ago

As mentioned, the json gem does not allow encoding strings directly. I'll take a look a Yajl.

mjc Over a year ago

For JSON gem compatibility in yajl you can do require 'yajl/json_gem'

Stewart Over a year ago

It's worth noting that this answer assumes that the question poster is using rails(however this was not stipulated in the question). JSON.encode is provided by rails as is object.to_json. For uses outside of rails use JSON.generate which is in ruby 1.9.3 std-lib.

Hezad Over a year ago

@Stewart comment should definitely be added to that answer imho

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