Module Overview

What You’ll Learn

• Explain why manual if checks don’t scale as validation for a real API
• Define a schema and validate request data against it with Zod
• Return clear, structured validation errors to a client

💡 Why this matters: Earlier courses in this track validated input with a scattered if (!req.body.title) here and there. A real API, especially one with authentication and roles now in the picture, needs validation that’s consistent, complete, and impossible to accidentally skip.

What’s Covered

• Why manual validation breaks down, as a request body grows more fields and more rules.
• Zod schemas, defining the exact shape data must have.
• Validating request bodies, rejecting invalid input before it reaches a controller.
• Structured error responses, telling a client exactly what was wrong, and with which field.

Hands-On

By the end of this module, you’ll have validation middleware that rejects malformed registration and login requests with clear, field-specific errors, before any controller logic runs.

Next module: hardening this API against the kinds of attacks real APIs face.