Customer and employee deletion safety and deactivation

[NikosPoly]

Currently customers and employees can be hard deleted regardless of their loan history,
which would orphan loan records in MongoDB.

Two approaches are being considered — one needs to be chosen:

Option A — Loan history check before delete

• Before deleting a customer, check if they have any loan history
• If loan history exists, block deletion entirely

Option B — Soft delete via active boolean

• Add active boolean field to Customer and Employee (default true)
• Instead of deleting, set active = false
• GET endpoints should only return active = true records by default
• Preserves full loan history

Note

Option B is the preferred approach for a real library system but adds more complexity.
Decision needed before implementation.