defineRoute

defineRoute declares exactly one endpoint. It is the heart of baguette: a single object whose zod schemas become runtime validation, inferred handler types, the OpenAPI spec, and the error funnel — all at once. Every file in api/ default-exports one call to it.

// api/customers/[id].ts  ->  GET /api/customers/{id}
import { defineRoute, z } from "@prehoy/baguette";

export default defineRoute({
  method: "get",
  summary: "Get a customer",
  tags: ["Customers"],
  request: { params: z.object({ id: z.string() }) },
  response: z.object({ id: z.string(), name: z.string() }),
  handler: (c, { params }) => c.json({ id: params.id, name: "Ada" }),
});

The path comes from the file

You never write the URL. It is derived from the file's location under api/:

A [segment] in a filename becomes an OpenAPI {segment} path parameter — declare it in request.params with a matching key.

The route object

method

One of "get", "post", "put", "patch", "delete". One method per file.

request

Up to three zod schemas, each optional:

• params — path parameters. Keys must match the [segment]s in the filename.
• query — the query string. Coercion and defaults work as normal zod.
• body — the JSON body. It is parsed lazily, straight through the schema — there is no parse-everything middleware and the body is never read manually.

request: {
  params: z.object({ id: z.string() }),
  query: z.object({ expand: z.boolean().default(false) }),
  body: z.object({ items: z.array(ItemSchema) }),
}

Whatever you declare arrives on the handler's second argument, validated and fully typed. Anything that fails validation returns 400 before your handler runs.

response

A single zod schema is the 200 body:

response: OrderSchema,

Or map status codes to schemas when an endpoint has more than one shape:

response: {
  200: OrderSchema,
  404: z.object({ error: z.string() }),
},

The response schema feeds the OpenAPI spec so the generated docs describe exactly what a caller receives.

handler

handler: (c, input) => c.json(/* ... */)

• c is the Hono Context — use c.json, c.req.header, and so on.
• input is { params, query, body }, containing only the schemas you declared, fully typed.

Handlers may be async. An unhandled throw is caught by the error funnel and returned as a clean 500, so you only handle the errors you care about.

handler: async (c, { params, body }) => {
  const order = await createOrder(params.id, body);
  return c.json(order);
}

summary & tags

Optional OpenAPI metadata. summary titles the operation; tags group it in the Scalar sidebar.

The one escape hatch

For a genuinely schema-less endpoint — most often a third-party webhook that must accept any payload — default-export a plain Hono handler instead of a defineRoute. The loader mounts it with app.all:

// api/webhooks/incoming.ts
import type { Context } from "hono";

// Blessed exception to "all I/O through zod": an external webhook.
export default async function incomingWebhook(c: Context) {
  const body = await c.req.json().catch(() => null);
  return c.json({ received: true });
}

This is the only sanctioned way to skip schemas, and it is lint-flagged so it stays rare. Everything else goes through zod.

Related

• serve — load a directory of routes and start the server.
• CLI — baguette new route <path> scaffolds a route in the right place.
• Clean-code contract — the rules defineRoute is built to enforce.