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Frameworks & web · #fastify
Learn why Fastify decorators appear undefined in async plugins and how to fix encapsulation, ordering, and timing issues with a step‑by‑step diagnostic guide.
Fastify lets you attach JSON Schemas to routes for early validation and auto‑generates OpenAPI docs with fastify‑oas. Learn how to set up schemas, test validation, customize errors, and weigh the trade‑offs for production APIs.
Stop writing repetitive validation logic in your route handlers. Learn how Fastify uses JSON Schema to compile optimized validation and serialization functions.
Learn how to diagnose and fix hanging requests in Fastify, from identifying event loop blockage and missing next() calls to resolving database connection pool exhaustion.
Learn when to use Fastify's built‑in JSON Schema for request validation and response serialization, see trade‑offs, and view a shared‑schema example.
Learn when to use Fastify's built-in JSON Schema validation versus custom preHandler logic to optimize API performance and maintain data integrity.
Stop writing repetitive validation logic. Learn how Fastify uses JSON Schema and fast-json-stringify to automate input validation and prevent accidental data leaks in your API responses.
I am developing a Fastify plugin that adds a decorator based on the current database schema. When I need to alter the schema, I want to be able to revert the plugin’s changes if the migration fails, while keeping the plugin encapsulated and its dependencies validated through fastify-plugin. The plugin is registered with a name, dependencies, and encapsulate:
A Fastify route returns pages from a table with millions of rows. Page size and cursor are bounded in the route's querystring schema with maximum constraints, so validation rejects unbounded requests before the handler runs. The decision is how the page payload leaves the server. One approach uses a response schema so Fastify compiles a fast-json-stringify s
nodejs