LESSON 4.2
Forms, validation, and error states
Learn key techniques and workflows in Next.js App Router in Depth.
16m
intermediate
8,816 students
Overview
Client-side validation is a convenience; the server check is the real one. Parse the payload on arrival and return errors the form can render.
In this lesson you will:
- Validate submitted data on the server before writing
- Return structured field errors back to the form
- Keep the form usable when JavaScript has not loaded
Pro Tip
Never trust the shape of an incoming payload. Parse it, then use the parsed value.