Validation

Rasengan Server integrates @rasenganjs/validators directly — attach a schema to a route and validation middleware is injected automatically, ahead of your handler.

import z from "zod";
 
routes(router: Router) {
  router.post("/users", this.create, { body: z.object({ name: z.string() }) });
}

If validation fails, the handler never runs — the request short-circuits with a 400 JSON error response by default.

Global Configuration

import { zodAdapter } from '@rasenganjs/validators';
 
bootstrap((app) => {
  app.configureValidation({
    adapter: zodAdapter, // this is already the default
    onError: (errors, ctx) =>
      Response.json({ code: 'VALIDATION_ERROR', errors }, { status: 422 }),
  });
});

ServerApp defaults to zodAdapter and a 400 JSON error handler — you only need configureValidation() to change the adapter or customize the error response shape/status.

What Gets Validated

interface SchemaDefinition {
  body?: ZodSchema;
  params?: ZodSchema;
  query?: ZodSchema;
  onError?: (
    errors: ValidationError[],
    ctx: Context
  ) => Response | Promise<Response>; // per-route override
}

router.put('/users/:id', this.update, {
  params: z.object({ id: z.coerce.number() }),
  query: z.object({ notify: z.coerce.boolean().optional() }),
  body: z.object({ name: z.string().optional() }),
});

• params — validated data is merged into ctx.params in place.
• query — validated data is available via ctx.get('validatedQuery') (not merged into ctx.query itself).
• body — ctx.body is replaced with the validated/coerced data (and also stored under ctx.get('parsedBody')).

Per-route Error Override

router.post('/users', this.create, {
  body: CreateUserSchema,
  onError: (errors) => Response.json({ errors }, { status: 422 }),
});

A schema's own onError takes priority over the global configureValidation({ onError }) handler for that one route.

Controller-level Schemas

Declaring schemas once on the controller and referencing them by method name avoids repeating the schema at every router.post(...) call — see Controllers & Routing for the full pattern, including why the schema is still passed as a trailing argument for TypeScript inference even though the runtime also matches it by method name.