Rails GET request pulling down previously downloaded data

Question

I'm working with an external API to receive pending orders. I've successfully written a GET request method that saves any pending orders to PostgreSQL.

The issue I'm having is that during each GET request, I'm creating duplicates because it's downloaded all the pending orders (old and new) again.

Is there a way during my GET request, I can check against the database for previously downloaded pending orders, ignore them, and download only newly created pending orders?

REST Gem I'm using:

rest-client

Here's my working GET request:

def download_pf_orders
  download_count = 0
  uri = "#{PF_TEST_PENDING_API_URL}"
  rest_resource = RestClient::Resource.new(uri, PF_TEST_USERNAME, PF_TEST_PASSWORD)

  begin
    response = rest_resource.get(accept: 'application/json')
    json = JSON.parse(response)

    json.each do |data|

      sequence = data['SequenceNumber']
      puts "### Last Sequence Number: #{sequence}"

      PfOrder.create(
        sequence_number: data['SequenceNumber'],
        message_guid: data['MessageGuid'],
        hl7_document: data['Hl7Document']
        )
      download_count += 1
    end
  rescue => e
    puts "### Status Code: #{e.response.code} ###"
  end
  puts "### Downloaded Orders: #{download_count} ###"
end

Answer 1

I figured this out. Here's my updated GET method:

def download_pf_orders
  download_count = 0
  uri = "#{PF_TEST_PENDING_API_URL}"
  rest_resource = RestClient::Resource.new(uri, PF_TEST_USERNAME, PF_TEST_PASSWORD)

  begin
    response = rest_resource.get(accept: 'application/json')
    json = JSON.parse(response)

    json.each do |data|

      sequence = data['SequenceNumber']
      puts "### Last Sequence Number: #{sequence}"

      pending_order = PfOrder.new(
        sequence_number: data['SequenceNumber'],
        message_guid: data['MessageGuid'],
        hl7_document: data['Hl7Document'],
        )

      sn = pending_order.sequence_number
      mg = pending_order.message_guid
      hd = pending_order.hl7_document

      PfOrder.find_or_create_by(sequence_number: sn, message_guid: mg, hl7_document: hd)

      download_count += 1
    end
  rescue => e
    puts "### Status Code: #{e.response.code} ###"
  end
  puts "### Downloaded Orders: #{download_count} ###"
end