Validated Handler

Wraps Next.js App Router API routes with automatic Zod validation so you stop writing the same 30 lines of query parsing and error handling in every endpoint. You define a Zod schema, specify if it's validating query params or body, and get back fully typed input with consistent 400 responses when validation fails. Especially useful if you're building pagination across multiple routes since you can share schemas like paginationInputSchema and eliminate the manual coercion and range checking. The pattern shines when you have dozens of routes and want uniform error formats without boilerplate.

skills.sh installs: 332
GitHub stars: 79
last updated: Aug 21, 2026

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Install

$ npx -y skills add bobmatnyc/claude-mpm-skills --skill validated-handler --agent claude-code

Installs into .claude/skills of the current project.

Files

Next.js Validated Handler Pattern

Type-safe API route handler with automatic Zod validation for Next.js App Router.

When to Use This Skill

Use this skill when:

Building Next.js API routes (App Router)
Want automatic input validation with Zod
Need consistent error handling across API routes
Want to eliminate boilerplate validation code
Building type-safe APIs with TypeScript

The Problem

Without a validated handler, every API route has repetitive validation code:

// ❌ REPETITIVE - Every route looks like this
export async function GET(request: NextRequest) {
  try {
    // 1. Parse query params
    const { searchParams } = new URL(request.url);
    const rawPage = searchParams.get('page');
    const rawLimit = searchParams.get('limit');

    // 2. Validate each param manually
    if (!rawPage || isNaN(Number(rawPage))) {
      return NextResponse.json(
        { error: 'Invalid page parameter' },
        { status: 400 }
      );
    }

    if (!rawLimit || isNaN(Number(rawLimit))) {
      return NextResponse.json(
        { error: 'Invalid limit parameter' },
        { status: 400 }
      );
    }

SKILL.md on GitHub