User context in rest application

I have an angularjs application with rest java backend behind.

I want to limit each user to his context, like user can have access only to data that belongs him in relational database

(like, user can only have access to his calculations data, only to his files, etc).

What's the best approach to do that?

I can check if user have access to that data in each database query, but it looks like a lot of joins constructions, maybe there's another good way to solve that problem?

Thanks for you help