Mailgun SDK unable to find required classes (php) - php

Question

I'm trying to use the Mailgun API SDK to send emails from my test server. I downloaded the SDK itself as I am not currently using Composer.
However, when I try to instantiate a Mailgun object, I get this error:
Fatal error: Class 'Mailgun\Connection\RestClient' not found in /var/www/mysite.xyz/www/inc/libs/Mailgun/Mailgun.php on line 38
Which I fixed by adding require "Connection/RestClient.php"; to the Mailgun.php file. However, this in turn caused its own error.
Fatal error: Class 'GuzzleHttp\Client' not found in /var/www/mysite.xyz/www/inc/libs/Mailgun/Connection/RestClient.php on line 41
This is included in my includes.php, so for all pages.
#Mailgun php functions
require_once "libs/Mailgun/Mailgun.php";
use Mailgun\Mailgun;
Then, when I try to use this;
# First, instantiate the SDK with your API credentials and define your domain.
$mg = new Mailgun\Mailgun("key-myactualkey");
$domain = "myactualdomain.xyz";
print "Email to send is ".$welcomeemail; #Never gets reached
It causes those fatal errors and the program grinds to a halt.
Why is this happening and how do I fix it?

Answer 1

I had the same problem and fixed it by using composer which is easier then you might think. Just follow these instructions (locally, on your computer, where PHP should be installed):
https://github.com/mailgun/mailgun-php/blob/master/SharedHostInstall.md
Then upload all files generated to your server in a separate directory.
Then include the following lines to your script:
require 'your/path/to/these/files/vendor/autoload.php';
use Mailgun\Mailgun;
Create a new Mailgun object like this:
$mg = new Mailgun("your-secret-key");