Tags — Ahmet Zeybek

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~/tips/today — 2026-09-13

~cat tips/today

Validate once at the edge, then trust the types

typescriptvalidation

Parsing the same payload with a schema in three layers is slow and it means nobody trusts the layer above. Parse where data enters, request bodies, environment, external APIs, and pass typed values inward.

const body = CreateOrder.parse(await req.json()); // the only parse
await createOrder(body);                          // typed from here on

z.infer<typeof CreateOrder> is the type the inner code takes. If a value has that type, it was validated, by construction.

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