Chapter quiz · Schemas & Validation

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8 questions on Schemas & Validation. Pass 70% to clear the chapter.

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Schemas & Validation — Chapter Quiz

Eight questions on JSON Schema for body, params, query, and response, TypeBox, Ajv tuning, error formats, and Swagger.

0/ 9

Question 1
1
Which schema part validates URL path parameters like /users/:id?
AbodyBparamsCquerystringDheaders
schema.params validates URL params (:id, :slug). querystring validates ?key=value, and body validates the request payload.
Question 2
2
What spec do Fastify schemas use under the hood?
AOpenAPI 3.1BJSON Schema (via Ajv)CZodDJoi
Fastify uses Ajv to compile JSON Schemas. TypeBox and similar libraries are just nice TypeScript wrappers that output JSON Schema.
Question 3
3
A response schema can both shape the output and speed up JSON serialization.
TTrueFFalse
A response schema feeds fast-json-stringify, which is roughly 2-3x faster than JSON.stringify. It also strips unknown properties — handy for hiding sensitive fields.
Question 4
4
What is TypeBox?
AA typed wrapper that builds JSON Schemas and infers TypeScript types from themBA runtime alternative to AjvCA code generator that scaffolds Fastify routesDA Fastify plugin for typed env vars
Type.Object({ ... }) returns a real JSON Schema and a TypeScript type at the same time — one source of truth for runtime validation and compile-time inference.
Question 5
5
To enable string-to-number coercion in querystrings, set the Ajv option named ____ to true.
coerceTypes tells Ajv to convert types where it can — most often used so ?limit=10 becomes the number 10 instead of failing validation.
Question 6
6
What status code does Fastify return when this body is rejected?
```
app.post('/x', {
  schema: { body: { type: 'object', required: ['email'] } },
}, async () => 'ok');
// POST /x with body {}
```
A200B400C422D500
Schema validation failures produce a 400 Bad Request with a structured error payload. You can change this via setErrorHandler or a custom schemaErrorFormatter.
Question 7
7
What does @fastify/swagger (with @fastify/swagger-ui) generate?
AA docs site from your route schemasBTypeScript types from your routesCA Postman collection at runtimeDA test suite from your routes
@fastify/swagger builds an OpenAPI document from your route schemas; @fastify/swagger-ui serves an interactive docs UI from that document.
Question 8
8
Which of these are valid keys inside a route's schema option?
Select all that apply.
AbodyBparamsCquerystringDresponseEmiddleware
The schema slots are body, params, querystring, headers, and response (keyed by status code). middleware is not a Fastify schema key.