repairshopr-php-invoice-creation-wrapper.php

<?php
  $subdomain = 'subdomain';
  $api_key = 'api_key';
  $api_version = '/api/v1';
  $base_url = "https://$subdomain.repairshopr.com";

  $subtotal = 150.00;
  $number = '12345';
  $invoice = array();
  $invoice["date"] = date('Y-m-d H:i:s');
  $invoice["paid"] = true;
  $invoice["date_received"] = date('Y-m-d H:i:s');
  $invoice["number"] = $number;
  $invoice["phone"] = '4255551212';
  $invoice["line_items"] = array(
    array("item" => "Labor", "name" => "Field Service Labor", "cost" => 12.0, "price" => 100, "quantity" => 1),
    array("item" => "Labor", "name" => "Field Service Labor Visit 2", "cost" => 12.0, "price" => 100, "quantity" => 0.5)
  );
  $data_string = json_encode($invoice);

  $ch = curl_init("{$base_url}{$api_version}/invoices.json?api_key=$api_key");

  curl_setopt($ch, CURLOPT_CUSTOMREQUEST, "POST");
  curl_setopt($ch, CURLOPT_POSTFIELDS, $data_string);
  curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
  curl_setopt($ch, CURLOPT_HTTPHEADER, array(
      'Content-Type: application/json',
      'Content-Length: ' . strlen($data_string))
  );
  curl_setopt($ch, CURLOPT_TIMEOUT, 5);
  curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 5);

  //get the result
  $result = curl_exec($ch);

  //close connection
  curl_close($ch);
  

Just add these two lines around line 10 and it's perfect.

$customer_id = "123456";
$invoice["customer_id"] = $customer_id;

I think $subtotal isn't used at all