Error Class for JSON API can be extended to serialize different execptional creatures.

error_serializer.rb

class ErrorSerializer
  attr_accessor :request, :params, :errors

  def initialize(request, params, errors = [], exception = nil)
    @request = request
    @params = params
    @errors = errors
    @exception = exception
  end

  def serialize
    {
      errors:
        @errors.map do |error|
          {
            id: @params[:id],
            status: error[:status],
            title: error[:title],
            message: error[:message],
            source: @request.parameters.merge({ url: @request.url }),
          }
        end,
    }.to_json
  end

  def not_found
    @errors = [
      {
        status: :not_found,
        message: @exception,
        title: 'ActiveRecord::RecordNotFound',
      },
    ]
    serialize
  end

  def conflict
    @errors = [
      {
        status: :conflict,
        message: "Lead already scanned for attendee #{@params[:id]}",
        exception: @exception,
        title: 'ActiveRecord::RecordNotUnique',
      },
    ]
    serialize
  end

  def unprocessable_entity
    @errors = [
      {
        status: :unprocessable_entity,
        message: @exception,
        title: 'ActiveRecord::RecordInvalid',
      },
    ]
    serialize
  end
end