api_on_rails VS Spree Commerce

Check out Alexandre Rousseau's API On Rails. You can buy the PDF/EPUB on Leanpub, or, if you are not afraid to generate his book yourself for free, visit https://github.com/madeindjs/api_on_rails.

You can give this a shot.

There are some results in Google. I saw this title too: API on Rails 6 Alexandre Rousseau

Yes, check out this one - working with it myself right now: https://leanpub.com/apionrails6

API on Rails 6 Rails API with TDD with minitest. Builds authenticated system with 5 models - costs $10.00, but you can give more if you feel generous. There's a github repo if you have issues.

A good system to study is Spree https://github.com/spree/spree. It has an inventory and billing system and supports different adjustments and sale configurations. If you don't want to use it wholesale it's a solid Rails application that does most of what you want so you can use it as solid inspiration.

Spree Commerce: https://spreecommerce.org/

Maybe Spree?

I'd say Solidus and Spree are you best options rather than trying to roll out you own ecommerce solution.

When I was working on that company, that mobile ordering app, Counterless, I looked a lot at codebases like Spree, the Spree Commerce codebase. And that's how I learned a lot about how do you model an order with line items and things like that? I saw some amazing things that helped me develop an understanding and save a ton of time by looking at oh, they have a state machine. What are the ways that an order transitions through all these different states as it gets processed and charged? And how do you track all of those things?