Start with the business event
A maintainable application starts with a clear understanding of what the business needs to happen. Instead of beginning with a list of screens, describe events such as confirming an order, receiving a payment, or approving a leave request. Each event has an actor, required information, rules, and an outcome.
For an order confirmation, the rules might include checking customer access, confirming that the order is still a draft, calculating totals, and recording the confirmation time. Writing these rules down makes the implementation easier to review with the business team.
Give each layer a clear responsibility
Request validation checks the shape of incoming data. Authorization decides who can perform the action. A dedicated action or service coordinates the business workflow, while models describe records and relationships. The controller connects the request to that workflow and returns an appropriate response.
- Keep validation close to the request boundary.
- Keep calculations in one place so different entry points produce consistent results.
- Use a database transaction for related changes that must succeed together.
- Dispatch background work only after the transaction commits when that work depends on saved data.
Test the rules that protect the business
Useful tests describe outcomes: an already confirmed order cannot be confirmed again, a user cannot change another company’s order, and a failed payment does not mark an invoice as paid. These checks are more valuable than tests that only repeat the internal method calls.
Keep the first version focused
Use the smallest structure that makes the workflow understandable. Introduce additional abstractions when real duplication or complexity appears. Consistent names and clear responsibilities help future developers change the system with confidence.