iq-scm / jmespath.rb

Ruby implementation of JMESPath

jmespath.rb

An implementation of JMESPath for Ruby. This implementation supports searching JSON documents as well as native Ruby data structures.

Installation

$ gem install jmespath

Basic Usage

Call JMESPath.search with a valid JMESPath search expression and data to search. It will return the extracted values.

require 'jmespath'

JMESPath.search('foo.bar', { foo: { bar: { baz: "value" }}})
#=> {baz: "value"}

In addition to accessing nested values, you can exact values from arrays.

JMESPath.search('foo.bar[0]', { foo: { bar: ["one", "two"] }})
#=> "one"

JMESPath.search('foo.bar[-1]', { foo: { bar: ["one", "two"] }})
#=> "two"

JMESPath.search('foo[*].name', {foo: [{name: "one"}, {name: "two"}]})
#=> ["one", "two"]

If you search for keys no present in the data, then nil is returned.

JMESPath.search('foo.bar', { abc: "mno" })
#=> nil

See the JMESPath specification for a full list of supported search expressions.

Indifferent Access

The examples above show JMESPath expressions used to search over hashes with symbolized keys. You can use search also for hashes with string keys or Struct objects.

JMESPath.search('foo.bar', { "foo" => { "bar" => "value" }})
#=> "value"

data = Struct.new(:foo).new(
  Struct.new(:bar).new("value")
)
JMESPath.search('foo.bar', data)
#=> "value"

JSON Documents

If you have JSON documents on disk, or IO objects that contain JSON documents, you can pass them as the data argument.

JMESPath.search(expression, Pathname.new('/path/to/data.json'))

File.open('/path/to/data.json', 'r', encoding:'UTF-8') do |file|
  JMESPath.search(expression, file)
end

Links of Interest

• Release Notes
• License
• JMESPath Tutorial
• JMESPath Specification

License

This library is distributed under the apache license, version 2.0

Copyright 2014 Trevor Rowe; All rights reserved.

Licensed under the apache license, version 2.0 (the "license"); You may not use this library except in compliance with the license. You may obtain a copy of the license at:

http://www.apache.org/licenses/license-2.0

Unless required by applicable law or agreed to in writing, software distributed under the license is distributed on an "as is" basis, without warranties or conditions of any kind, either express or implied.

See the license for the specific language governing permissions and limitations under the license.