ionic 3: How to create orderpay string to pass at alipay plug in from server side

Question

i have an existing ionic3 application i need to integrate alipay and we chat payment, i know there are plug for both but I need any reference of how to generate order string or payment object at server side (Php laravel 5.4) which can be pass to plugin's payment method.

I have go through alipay documentation but couldn't get proper guidance.

Any example code or any ref for the same would be appreciated.