Unable to create draft PayPal invoice using v2 API version - ruby-on-rails

Question

I am upgrading PayPal Invoicing feature from v1 to v2 (Because v1 is deprecated) in my Ruby on Rails application.
Since there's no official library/gem supporting v2 invoicing, so I decided to build everything as per this official documentation here: https://developer.paypal.com/docs/api/invoicing/v2.
The flow is like this:
System will get an access-token based on ClientID and ClientSecret
From this access-token, I will be generating a new invoice_number by sending curl request to: https://api.sandbox.paypal.com/v2/invoicing/generate-next-invoice-number
Upon receiving the invoice_number, I am sending curl request to create draft invoice endpoint with all the required data
curl -v -X POST https://api.sandbox.paypal.com/v2/invoicing/invoice
The issue I am facing is with the last point. I am getting 201 created response from create draft invoice endpoint but the endpoint is not returning me the complete invoice object along with Invoice ID.
Here's what I am getting:
"201"
{"rel"=>"self", "href"=>"https://api.sandbox.paypal.com/v2/invoicing/invoices/INV2-Z3K7-Y79X-36EM-ZQX8", "method"=>"GET"}
If you try opening this link, you'll see this:
{
"name":"AUTHENTICATION_FAILURE",
"message":"Authentication failed due to invalid authentication credentials or a missing Authorization header.",
"links": [
{
"href":"https://developer.paypal.com/docs/api/overview/#error",
"rel":"information_link"
}
]
}
Not sure what I am missing here!
Below is the code for reference:
require 'net/http'
require 'uri'
require 'json'
class PaypalInvoice
def initialize order
#order = order
#client_id = ENV['PAYPAL_CLIENT_ID']
#client_secret = ENV['PAYPAL_CLIENT_SECRET']
#base_url = ENV['AD_PP_ENV'] == 'sandbox' ? 'https://api.sandbox.paypal.com' : 'https://api.paypal.com'
#paypal_access_token_identifier = 'paypal_access_token'
#request_id ||= SecureRandom.uuid
end
def create_draft_invoice
raise "Paypal token not found" unless Rails.cache.exist?(#paypal_access_token_identifier)
invoice_number = "#141"
sleep 5
try = 0
uri = URI.parse(#base_url + "/v2/invoicing/invoices")
request = Net::HTTP::Post.new(uri)
request['X-PAYPAL-SANDBOX-EMAIL-ADDRESS'] = ENV['PAYPAL_CLIENT_EMAIL']
request['Authorization'] = "Bearer #{Rails.cache.fetch(#paypal_access_token_identifier)['access_token']}"
request['Content-Type'] = 'application/json'
request['PayPal-Request-Id'] = #request_id.to_s
request.body = JSON.dump({
"detail" => get_detail(invoice_number),
"invoicer" => get_invoicer,
"primary_recipients" => get_primary_recipients,
"items" => items_info,
"configuration" => {
"partial_payment" => {
"allow_partial_payment" => false,
},
"allow_tip" => false,
"tax_calculated_after_discount" => true,
"tax_inclusive" => true
}
})
req_options = {
use_ssl: uri.scheme == "https",
}
response = Net::HTTP.start(uri.host, uri.port, req_options) do |http|
http.request(request)
end
p 'method: create_draft_invoice. response: '
p response.code
p JSON.parse(response.body)
raise "Paypal token expired" if response.code.to_s == '401'
rescue RuntimeError => error
p "#{error.to_s}"
try += 1
access_token_response_status = get_new_access_token
retry if access_token_response_status.to_s == '200' and try <= 1
end
end

Answer 1

This:
{"rel"=>"self", "href"=>"https://api.sandbox.paypal.com/v2/invoicing/invoices/INV2-Z3K7-Y79X-36EM-ZQX8", "method"=>"GET"}
Is the endpoint for an API call, specifically 'Show invoice details': https://developer.paypal.com/docs/api/invoicing/v2/#invoices_get
Loading it in a browser w/o an Authorization: Bearer <Access-Token> header will give an AUTHENTICATION_FAILURE.
There's currently a bug in Sandbox with unconfirmed emails, so make sure your Sandbox emails are confirmed