jrq
jrq is a CLI JSON processor for Rubyists. jrq enable you to filter/map/reduce JSON without studying new syntax.
$ echo '{"foo": [1, 2, 3], "bar": 100 }' \
| jrq '_.foo.reduce(&:+) * _.bar' # => 600
Installation
Add this line to your application's Gemfile:
gem 'jrq'
And then execute:
$ bundle
Or install it yourself as:
$ gem install jrq
Usage
JSON data from STDIN will be parsed and passed as _
variable. Because jrq just evaling given string in the context of Ruby, actually it's almost same as doing like cat a.json | ruby -rjson -e "JSON.load(STDIN)['foo']"
. Here are some samples below:
_
is a Hash, so _.keys
would be nice place to start with.
$ aws ec2 describe-instances \
| jrq '_.keys'
[
"Reservations"
]
jrq parses given JSON with Hashie::Mash, so you can access json fields with dot(.
) like Ruby's method access.
$ aws ec2 describe-instances \
| jrq '_.Reservations.class'
Array
Then digging deeper...
$ aws ec2 describe-instances \
| jrq -r '_.Reservations.map{|r| r.keys }.flatten.uniq'
[
"OwnerId",
"ReservationId",
"Groups",
"Instances",
"RequesterId"
]
... to get information you need.
$ aws ec2 describe-instances \
| jrq 'ins = _.Reservations.first.Instances.first;
[ins.InstanceId, ins.VpcId, ins.SubnetId, ins.PrivateIpAddress]'
[
"i-aaaaaaaa",
"vpc-5dxxxxx8",
"subnet-a1xxxxx6",
"172.31.25.92"
]
$ aws ec2 describe-instances \
| jrq '_.Reservations.map{|r| r.Instances.map{|i| i.InstanceId } }.flatten'
[
"i-aaaaaaaa",
"i-bbbbbbbb",
"i-cccccccc",
"i-dddddddd",
]
With -r
or --raw
option, raw output would be displayed. It's suitable for passing to another program as input.
$ aws ec2 describe-instances \
| jrq -r '_.Reservations.map{|r| r.Instances.map{|i| i.InstanceId } }.flatten'
i-aaaaaaaa
i-bbbbbbbb
i-cccccccc
i-dddddddd
You can even require another Ruby library.
$ curl -s https://ip-ranges.amazonaws.com/ip-ranges.json \
| jrq 'require "ipaddr"; _.prefixes.select{|p| p.region == "ap-northeast-1" }.map{|p| IPAddr.new(p.ip_prefix).to_i.to_s(2) }'
[
"11011000000000000000000000000",
"101110001100111110000000000000",
"110100010001000000000000000000",
"110100010111000011110000000000",
"110100010111000101000000000000",
...
Development
After checking out the repo, run bin/setup
to install dependencies. Then, run rake test
to run the tests. You can also run bin/console
for an interactive prompt that will allow you to experiment. Run bundle exec jrq
to use the gem in this directory, ignoring other installed copies of this gem.
To install this gem onto your local machine, run bundle exec rake install
. To release a new version, update the version number in version.rb
, and then run bundle exec rake release
, which will create a git tag for the version, push git commits and tags, and push the .gem
file to rubygems.org.
Build & Push to rubygems.org
$ gem build jrq.gemspec
then
$ gem install jrq-x.y.z.gem
or
$ gem push jrq-x.y.z.gem
Plan & TODOs
-
color
-
launch REPL when STDIN isn't given
- jrq foo.json => also launch REPL
-
prepare sample JSON data
- AWS ip-ranges.json
- CloudFormation Template
- ECS Task Definition
- JSON Schema / Swagger
Contributing
Bug reports and pull requests are welcome on GitHub at https://github.com/memerelics/jrq/issues
License
The gem is available as open source under the terms of the MIT License.