jsonpointer

Parsing and resolution of JSON Pointer strings in Crystal.

Installation

1. Add the dependency to your shard.yml:

   dependencies:
     jsonpointer:
       github: aarongodin/jsonpointer
   

2. Run shards install

Usage

Create new pointer instances by calling the #from method using a source string for the pointer:

require "jsonpointer"
require "json"

input = JSON.parse(
  <<-JSON
  {
    "root": {
      "child": [
        { "name": "first" },
        { "name": "second" },
        { "name": "third" },
      ]
    }
  }
  JSON
)

pointer = JSONPointer.from("/root/child/2/name")
pointer.get?(input) # => "third" (as JSON::Any)

The accessor returned from JSONPointer#from has both #get and #get? methods. The #get raises an error when a value is not found in the input JSON, while #get? returns nil.

You can retrieve the original source string using #source:

require "jsonpointer"

pointer = JSONPointer.from("/root/child")
pointer.source # => "/root/child"

Escape sequences

The escape sequence in JSON Pointer is using a ~ character.

• ~0 => ~
• ~1 => /

The tilde (~) and forward slash are the only two characters you can escape using the above sequences. Example:

require "json"
require "jsonpointer"

input = JSON.parse(
  <<-JSON
  {
    "~aaron": {
      "id": "asdf1234"
    }
  }
  JSON
)

JSONPointer.from("/~0aaron/id").get? input # => "asdf1234" (as JSON::Any)

Contributing

1. Fork it (https://github.com/aarongodin/jsonpointer/fork)
2. Create your feature branch (git checkout -b my-new-feature)
3. Commit your changes (git commit -am 'Add some feature')
4. Push to the branch (git push origin my-new-feature)
5. Create a new Pull Request

References

• node-jsonpointer - used as a reference and test suite for this shard
• RFC 6901