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# frozen_string_literal: true
require "active_support/concern"
module Decidim
# This module adds support functionality to be able to generate a unique fingerprint
# from a model, given some fields. Its goal is to provide a way to give an informal
# "receipt" to a user to they can detect tampering.
#
module Fingerprintable
extend ActiveSupport::Concern
class_methods do
attr_reader :fingerprint_options
# Public: Configures fingerprinting for this model.
#
# fields - An `Array` of `symbols` specifying the fields that will be part of
# the fingerprint generation.
# block - (optional) When provided, it's given an instance of the model as a
# parameter so the fingerprint can be generated in runtime.
#
# Returns nothing.
def fingerprint(fields: nil, &block)
@fingerprint_options = {}
if block_given?
@fingerprint_options[:block] = block
else
raise "You must provide a set of fields to generate the fingerprint." unless fields
@fingerprint_options[:fields] = fields
end
end
end
# Public: Returns an instance of `FingerprintCalculator` containing the fingerprint.
#
# Example:
#
# model.fingerprint.value # Returns the fingerprint as a String
# model.fingerprint.source # Returns the source String (usually a json) from which
# # the fingerprint is generated.
def fingerprint
@fingerprint ||= FingerprintCalculator.new(fingerprint_data)
end
private
def fingerprint_data
options = self.class.fingerprint_options
if options[:block]
options[:block].call(self)
elsif options[:fields]
options[:fields].each_with_object({}) do |field, result|
result[field] = send(field)
end
else
raise "Fingerprinting needs to be set up via the `fingerprint` class method."
end
end
end
end
Version data entries
21 entries across 21 versions & 1 rubygems