Path Variables & Request Params

Introduction

Two ways data flows into a controller: path variables identify a resource (/orders/42), query params filter or paginate (?status=PAID&page=1).

Informative example

@GetMapping("/users/{userId}/orders/{orderId}")
public OrderDto get(
    @PathVariable Long userId,
    @PathVariable Long orderId
) { ... }

@GetMapping("/orders")
public Page<OrderDto> search(
    @RequestParam(required = false) OrderStatus status,
    @RequestParam(defaultValue = "0") int page,
    @RequestParam(defaultValue = "20") @Max(100) int size
) { ... }

Best practices

• Use path vars for identity; query params for filtering/sorting/paging.
• Bound page size with @Max — unbounded pages OOM your DB.
• Default everything sensibly; clients should be able to call /orders with no params.