canvas-lms/lib/custom_validations.rb

#
# Copyright (C) 2011 Instructure, Inc.
#
# This file is part of Canvas.
#
# Canvas is free software: you can redistribute it and/or modify it under
# the terms of the GNU Affero General Public License as published by the Free
# Software Foundation, version 3 of the License.
#
# Canvas is distributed in the hope that it will be useful, but WITHOUT ANY
# WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
# A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
# details.
#
# You should have received a copy of the GNU Affero General Public License along
# with this program. If not, see <http://www.gnu.org/licenses/>.
#

module CustomValidations


  module ClassMethods

    def validates_as_url(*fields, allowed_schemes: %w{http https})
      validates_each(fields, :allow_nil => true) do |record, attr, value|
        begin
          value, uri = CanvasHttp.validate_url(value, allowed_schemes: allowed_schemes)

          record.send("#{attr}=", value)
        rescue URI::Error, ArgumentError
          record.errors.add attr, 'is not a valid URL'
        end
      end
    end

    def validates_as_readonly(*fields)
      validates_each(fields) do |record, attr, value|
        if !record.new_record? && record.send("#{attr}_changed?")
          record.errors.add attr, "cannot be changed"
        end
      end
    end

    # alloweds is a hash of old_value => [new_value]
    # on update, only those transitions will be allowed for the given field
    def validates_allowed_transitions(field, alloweds)
      validates_each(field) do |record, attr, value|
        if !record.new_record? && record.send("#{attr}_changed?")
          old_val = record.send("#{attr}_was")
          unless alloweds.any? { |old,news| old_val == old && Array(news).include?(value) }
            record.errors.add attr, "cannot be changed to that value"
          end
        end
      end
    end
  end

  def self.included(klass)
    if klass < ActiveRecord::Base
      klass.send :extend, ClassMethods
    end
  end

end