jr: command-line JSON processor for Rubyists
jr is jq like JSON processor.
Its script can be written not a specific language but Ruby!
Installation
Add this line to your application's Gemfile:
gem 'jr-cli'
And then execute:
$ bundle
Or install it yourself as:
$ gem install jr-cli
Usage
jr filter can be written in Ruby!
$ jr [options] <jr filter> [file...]
You can also read JSON not from files but from STDIN.
options
--require FILE require the FILE before execution
-c, --compact-output output each JSON in single line
-f, --from-file FILE read filter from file
-r, --raw-output output strings as raw output
-R, --raw-input read each line as string
-C, --color-output output with colors even if writing to a pipe or a file
-M, --monochrome-output output without colors
-n, --null-input use null as input instead of any files
--unbuffered output each JSON without buffering
jr filter tutorial
Let's process JSON of GitHub API!
At first, download JSON of repos into your local to avoid API rate limit.
$ curl -s 'https://api.github.com/users/yuya-takeyama/repos?per_page=100' > repos.json
Unwrap Array with Enumerable#unwrap
Because response from GET /users/:username/repos is wrapped with Array, unwrap it using Enumerable#unwrap.
It's a built-in method of jr.
You'll get stream of JSON reperesents repositories.
$ jr 'unwrap' repos.json
Aggregate data with methods of Enumerable
Enumerable has many useful methods and you can transform data with them.
$ jr 'unwrap.group_by(&:language).map{|k, v| [k, v.size] }.sort_by{|k, v| -v }' repos.json
[
"Ruby",
28
]
[
"PHP",
22
]
[
"Go",
17
]
(...omitted...)
[
"VimL",
1
]
[
"CoffeeScript",
1
]
[
"Perl",
1
]
Output as text
You can transform JSONs into String and output as raw text using -r option.
$ jr 'unwrap.group_by(&:language).map{|k, v| [k, v.size] }.sort_by{|k, v| -v }.map{|l, s| "#{s}\t#{l}" }' -r repos.json
28 Ruby
22 PHP
17 Go
12 JavaScript
11
3 CSS
2 Shell
2 C
1 VimL
1 CoffeeScript
1 Perl
Basic mechanism
It's helpful to know jr's basic mechanism.
Shortly, jr is implemented like below.
json_enumerator.instance_eval { your_jr_filter_runs_here }
# And print its resultContributing
- Fork it ( https://github.com/yuya-takeyama/jr/fork )
- Create your feature branch (
git checkout -b my-new-feature) - Commit your changes (
git commit -am 'Add some feature') - Push to the branch (
git push origin my-new-feature) - Create a new Pull Request