A Ruby class to create and manage JSON-RPC data structures

json_rpc_object.gemspec

# frozen_string_literal: true

# This gemspec currently describes a gem hosted on Github as a Gist only.
# See https://bundler.io/guides/git.html

require_relative "json_rpc_object_version.rb"

Gem::Specification.new do |spec|
  spec.name = "json_rpc_object"
  spec.version = JsonRpcObject::VERSION
  spec.authors = ["wbr"]
  spec.email = ["jsonrpcobject@jamulii.com"]

  spec.summary = "Simple ruby objects to manage json-rpc 2.0 data structures"
  #spec.description = "TODO: Write a longer description or delete this line."
  spec.homepage = "https://gist.github.com/ginjo/5b128c655e79e1b4e0e10c27a5098177"
  spec.license = "MIT"
  spec.required_ruby_version = ">= 2.6.0"

  #spec.metadata["allowed_push_host"] = "TODO: Set to your gem server 'https://example.com'"

  spec.metadata["homepage_uri"] = spec.homepage
  spec.metadata["source_code_uri"] = spec.homepage
  #spec.metadata["changelog_uri"] = "TODO: Put your gem's CHANGELOG.md URL here."

  # Specify which files should be added to the gem when it is released.
  # The `git ls-files -z` loads the files in the RubyGem that have been added into git.
  spec.files = Dir.chdir(__dir__) do
    `git ls-files -z`.split("\x0").reject do |f|
      (f == __FILE__) || f.match(%r{\A(?:(?:bin|test|spec|features)/|\.(?:git|travis|circleci)|appveyor)})
    end
  end
  spec.bindir = "."
  spec.executables = spec.files.grep(%r{\Aexe/}) { |f| File.basename(f) }
  spec.require_paths = ["."]

  # Uncomment to register a new dependency of your gem
  # spec.add_dependency "example-gem", "~> 1.0"

  # For more information and examples about making a new gem, check out our
  # guide at: https://bundler.io/guides/creating_gem.html
end

json_rpc_object.rb

require 'securerandom'
require 'json'
require_relative 'json_rpc_object_version'
#
# A simple class to build json-rpc request, notification, response, and error structures.
# This is a Gist on Github.
#
# https://gist.github.com/ginjo/5b128c655e79e1b4e0e10c27a5098177
#
# Automatically inserts IDs where appropriate.
# Provides methods to create a response/error object from a request object.
# Existing strings or hashes can be loaded into the class and use the above-mentioned methods.
#
class JsonRpcObject < Hash
  
  ErrorCodes = {
    '-32700' => ['Parse error',	'Invalid JSON was received by the server. An error occurred on the server while parsing the JSON text.'],
    
    '-32600' =>	['Invalid Request',	'The JSON sent is not a valid Request object.'],
    '-32601' =>	['Method not found',	'The method does not exist / is not available.'],
    '-32602' =>	['Invalid params',	'Invalid method parameter(s).'],
    '-32603' =>	['Internal error',	'Internal JSON-RPC error.'],
    '-32000' =>	['Server error',	'-32000 to -32099 Reserved for implementation-defined server-errors.']
  }
  
  
  ###  CLASS METHODS  ###  
  
  class << self
        
    def common
      self[{'jsonrpc' => "2.0"}]
    end
  
    # Creates a request object.
    #
    def request(method, params=nil)
      common.merge(
        'method' => method,
        'params' => params,
        'id'     => SecureRandom.uuid
      )
    end
  
    # Creates a notification object (no id).
    #
    def notification(method=nil, params=nil)
      request(method, params).tap {|r| r.delete 'id'}
    end
    alias_method :notify, :notification
  
    # Creates a response object (id is required).
    #
    def response(id, result=nil)
      common.merge(
        'result' => result,
        'id'     => id
      )
    end
  
    # Creates an error object (code is required).
    # TODO: What about id? (See instance method #error below).
    #
    def error(code, data=nil, message=nil)
      out = common.merge(
        'code'    => code,
        'message' => message,
        'data'    => data
      )
      
      err_obj = ErrorCodes[out['code']]
      
      if err_obj
        out['message'] = "#{err_obj[0]}" + (message ? " : #{message}" : '')
      end
      
      out
    end
    
    # Loads and returns a JsonRpc object from JsonRpc, Hash, or String.
    # No validity checking is done.
    #
    def load(json_rpc)
      if json_rpc.is_a?(String)
        new.merge!(JSON.parse(json_rpc))
      elsif json_rpc.is_a?(Hash)
        new.merge!(load(json_rpc.to_json))
      end
    end
    
  end  # class methods
  
  
  ###  INSTANCE METHODS  ###
  
  # Creates a response from a request object (automatic id attachment).
  #
  def response(result, include_original:true)
    req = self.class.load(self)
    out = req.class.response(req['id'], result)
    if include_original
      out['request'] = req
    end
    
    out
  end
  
  # Creates an error from a request object (automatic id attachment).
  # Note that in ruby version < 3, if data is a hash, it will be interpreted
  # as keyword args (and fail) unless message is also given.
  # The solution is to always provide a message, even if it is nil.
  #
  def error(code, data=nil, message=nil, include_original:true)
    req = self.class.load(self)
    out = req.class.error(code, data, message)
    out['id'] = req['id']
    if include_original
      out['request'] = req
    end
    
    out
  end
    
end


# TODO: Consider using Hashie or hash-with-indiferent-access with this class.
# TODO: Create subclasses for Request, Response, Error, and Notification.
# TODO: What about error id?
# TODO: Change 'original' key name to 'request'.

json_rpc_object_version.rb

class JsonRpcObject < Hash
  VERSION = '0.0.1'
end