What is the correct way to load data from a databse once for use everywhere?

There could be multiple different ways to do this.

Cache
You can  fetch the required data and store it in cache (say in your BaseController) and give it a reasonable expiration time.
This would have the added benefit of being available for a multiple different requests too.

Factories
Factories is something that sounds like an exact match for you.


Of course you can also combine the above two... have a Factory instantiate a configuration object for you and then use a setter method in the object to set it's internal properties form cache/database call.
This way you will have the config loaded from cache and also you can access your object in all classes/models/etc.. where you need it.

Personally, in one of my projects I use factories to pass around the user. When a request comes in a filter checks the JWT token (from Auth header/cookie) and after validation it instantiates a user object using factories.
This way i can access the user details in my controllers/models and other libraries where i need it.