Error Serializer

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


# Example Use Case
#
# I was looking specifically for certain validation errors to send back detailed error
# messages to the api user. Could expand to contain Model.errors.full_messages but I wanted to follow the spec closer.
#

class Api::V3::LeadsController < Api::BaseController
  include RegHost
  before_action :set_attendee, only: %i[show create update]
  before_action :set_registration, only: %i[show create update]
  before_action :set_lead, only: %i[update]

  def index
    render json: LeadsSerializer.new(@user.leads), status: :accepted
  end

  def show
    render json: RegistrationSerializer.new(@registration), status: :accepted
  end

  # Setting the attendee is included in the RegHost concern
  def create
    begin
      @user.leads.create(
        event_exhibitor: @user.event_exhibitor,
        registration: @registration,
      )
      render json: RegistrationSerializer.new(@registration), status: :created
    rescue ActiveRecord::RecordNotUnique => exception
      render json: ErrorSerializer.new(request, params, [], exception).conflict,
             status: :conflict
    end
  end

  def update
    @lead.note.destroy if @lead.note.present?
    @lead.responses.destroy_all unless @lead.responses.blank?
    begin
      @lead.update!(lead_params)
      AddLeadToQualifierListJob.perform_later(@lead.id)
      render json: LeadsSerializer.new(@lead), status: :accepted
    rescue ActiveRecord::RecordInvalid => exception
      invalid_record(exception)
    rescue ActiveRecord::RecordNotFound => exception
      not_found(exception)
    end
  end

  private

  def lead_params
    params
      .require(:lead)
      .permit(
        note_attributes: :body,
        answers_attributes: %i[question_id body],
        responses_attributes: [:answer_id],
        qualifier_ids: [],
      )
  end

  def set_lead
    @lead =
      Lead.find_or_create_by!(
        registration: @registration,
        user: @user,
        event_exhibitor: @user.event_exhibitor,
      )
  rescue ActiveRecord::RecordNotFound => exception
    not_found(exception)
  rescue ActiveRecord::RecordNotUnique => exception
    render json: ErrorSerializer.new(request, params, [], exception).conflict,
           status: :conflict
  end

  def set_registration
    @registration =
      Registration.find_or_create_by!(event: @event, attendee: @attendee)
  rescue ActiveRecord::RecordNotFound => exception
    not_found(exception)
  rescue ActiveRecord::RecordInvalid => exception
    invalid_record(exception)
  end

  def not_found(exception)
    render json: ErrorSerializer.new(request, params, [], exception).not_found,
           status: :not_found
  end

  def invalid_record(exception)
    render json:
             ErrorSerializer.new(request, params, [], exception)
               .unprocessable_entity,
           status: :unprocessable_entity
  end
end