[joepie91_]

ORM or not, you still need constraints in the database, though.

There may be more than one client connecting to the database at the same time (or even internal inconsistencies within the same process), and the only way to prevent data inconsistencies is to hand the final responsibility of validation to the thing that is actually storing the data, ie. the database.

In the end, your database is the single source of truth, as it is the only part of your architecture that is technically capable of doing so. Client-side validation and server-side validation (in the application) are niceties for UX purposes, but do not and cannot replace database constraints.