Awesome
JSON implementation for Ruby
Description
This is an implementation of the JSON specification according to RFC 7159 http://www.ietf.org/rfc/rfc7159.txt . There is two variants available:
- A pure ruby variant, that relies on the
strscan
extensions, which is part of the ruby standard library. - The quite a bit faster native extension variant, which is in parts implemented in C or Java and comes with a parser generated by the Ragel state machine compiler.
Both variants of the JSON generator generate UTF-8 character sequences by default. If an :ascii_only option with a true value is given, they escape all non-ASCII and control characters with \uXXXX escape sequences, and support UTF-16 surrogate pairs in order to be able to generate the whole range of unicode code points.
All strings, that are to be encoded as JSON strings, should be UTF-8 byte sequences on the Ruby side. To encode raw binary strings, that aren't UTF-8 encoded, please use the to_json_raw_object method of String (which produces an object, that contains a byte array) and decode the result on the receiving endpoint.
Installation
It's recommended to use the extension variant of JSON, because it's faster than the pure ruby variant. If you cannot build it on your system, you can settle for the latter.
Install the gem and add to the application's Gemfile by executing:
$ bundle add json
If bundler is not being used to manage dependencies, install the gem by executing:
$ gem install json
There is also a pure ruby json only variant of the gem, that can be installed with:
$ gem install json_pure
Usage
To use JSON you can
require 'json'
to load the installed variant (either the extension 'json'
or the pure
variant 'json_pure'
). If you have installed the extension variant, you can
pick either the extension variant or the pure variant by typing
require 'json/ext'
or
require 'json/pure'
Now you can parse a JSON document into a ruby data structure by calling
JSON.parse(document)
If you want to generate a JSON document from a ruby data structure call
JSON.generate(data)
You can also use the pretty_generate
method (which formats the output more
verbosely and nicely) or fast_generate
(which doesn't do any of the security
checks generate performs, e. g. nesting deepness checks).
Handling arbitrary types
[!CAUTION] You should never use
JSON.unsafe_load
norJSON.parse(str, create_additions: true)
to parse untrusted user input, as it can lead to remove code execution vulnerabilities.
To create a JSON document from a ruby data structure, you can call
JSON.generate
like that:
json = JSON.generate [1, 2, {"a"=>3.141}, false, true, nil, 4..10]
# => "[1,2,{\"a\":3.141},false,true,null,\"4..10\"]"
To get back a ruby data structure from a JSON document, you have to call JSON.parse on it:
JSON.parse json
# => [1, 2, {"a"=>3.141}, false, true, nil, "4..10"]
Note, that the range from the original data structure is a simple
string now. The reason for this is, that JSON doesn't support ranges
or arbitrary classes. In this case the json library falls back to call
Object#to_json
, which is the same as #to_s.to_json
.
It's possible to add JSON support serialization to arbitrary classes by
simply implementing a more specialized version of the #to_json method
, that
should return a JSON object (a hash converted to JSON with #to_json
) like
this (don't forget the *a
for all the arguments):
class Range
def to_json(*a)
{
'json_class' => self.class.name, # = 'Range'
'data' => [ first, last, exclude_end? ]
}.to_json(*a)
end
end
The hash key json_class
is the class, that will be asked to deserialise the
JSON representation later. In this case it's Range
, but any namespace of
the form A::B
or ::A::B
will do. All other keys are arbitrary and can be
used to store the necessary data to configure the object to be deserialised.
If the key json_class
is found in a JSON object, the JSON parser checks
if the given class responds to the json_create
class method. If so, it is
called with the JSON object converted to a Ruby hash. So a range can
be deserialised by implementing Range.json_create
like this:
class Range
def self.json_create(o)
new(*o['data'])
end
end
Now it possible to serialise/deserialise ranges as well:
json = JSON.generate [1, 2, {"a"=>3.141}, false, true, nil, 4..10]
# => "[1,2,{\"a\":3.141},false,true,null,{\"json_class\":\"Range\",\"data\":[4,10,false]}]"
JSON.parse json
# => [1, 2, {"a"=>3.141}, false, true, nil, 4..10]
json = JSON.generate [1, 2, {"a"=>3.141}, false, true, nil, 4..10]
# => "[1,2,{\"a\":3.141},false,true,null,{\"json_class\":\"Range\",\"data\":[4,10,false]}]"
JSON.unsafe_load json
# => [1, 2, {"a"=>3.141}, false, true, nil, 4..10]
JSON.generate
always creates the shortest possible string representation of a
ruby data structure in one line. This is good for data storage or network
protocols, but not so good for humans to read. Fortunately there's also
JSON.pretty_generate
(or JSON.pretty_generate
) that creates a more readable
output:
puts JSON.pretty_generate([1, 2, {"a"=>3.141}, false, true, nil, 4..10])
[
1,
2,
{
"a": 3.141
},
false,
true,
null,
{
"json_class": "Range",
"data": [
4,
10,
false
]
}
]
There are also the methods Kernel#j
for generate, and Kernel#jj
for
pretty_generate
output to the console, that work analogous to Core Ruby's p
and
the pp
library's pp
methods.
Development
Release
Update the lib/json/version.rb
file.
rbenv shell 2.6.5
rake build
gem push pkg/json-2.3.0.gem
rbenv shell jruby-9.2.9.0
rake build
gem push pkg/json-2.3.0-java.gem
Author
Florian Frank mailto:flori@ping.de
License
Ruby License, see https://www.ruby-lang.org/en/about/license.txt.
Download
The latest version of this library can be downloaded at
Online Documentation should be located at