Web API Skill

Use this skill when building APIs for Adynato web projects.

Stack

• Framework: Next.js API Routes or App Router Route Handlers
• Validation: Zod
• Auth: NextAuth.js / Auth.js
• Database: Prisma + PostgreSQL
• Rate Limiting: Upstash

Route Handlers (App Router)

Basic Structure

app/
└── api/
    ├── auth/
    │   └── [...nextauth]/
    │       └── route.ts
    ├── users/
    │   ├── route.ts          # GET /api/users, POST /api/users
    │   └── [id]/
    │       └── route.ts      # GET/PATCH/DELETE /api/users/:id
    └── health/
        └── route.ts

Route Handler Pattern

// app/api/users/route.ts
import { NextRequest, NextResponse } from 'next/server'
import { z } from 'zod'
import { prisma } from '@/lib/prisma'
import { auth } from '@/lib/auth'

const createUserSchema = z.object({
  email: z.string().email(),
  name: z.string().min(1).max(100),
})

export async function GET(request: NextRequest) {
  try {
    const session = await auth()
    if (!session) {
      return NextResponse.json(
        { error: 'Unauthorized' },
        { status: 401 }
      )
    }

    const users = await prisma.user.findMany({
      select: { id: true, email: true, name: true },
    })

    return NextResponse.json({ data: users })
  } catch (error) {
    console.error('GET /api/users error:', error)
    return NextResponse.json(
      { error: 'Internal server error' },
      { status: 500 }
    )
  }
}

export async function POST(request: NextRequest) {
  try {
    const session = await auth()
    if (!session) {
      return NextResponse.json(
        { error: 'Unauthorized' },
        { status: 401 }
      )
    }

    const body = await request.json()
    const result = createUserSchema.safeParse(body)

    if (!result.success) {
      return NextResponse.json(
        { error: 'Validation failed', details: result.error.flatten() },
        { status: 400 }
      )
    }

    const user = await prisma.user.create({
      data: result.data,
    })

    return NextResponse.json({ data: user }, { status: 201 })
  } catch (error) {
    console.error('POST /api/users error:', error)
    return NextResponse.json(
      { error: 'Internal server error' },
      { status: 500 }
    )
  }
}

Dynamic Route Handler

// app/api/users/[id]/route.ts
import { NextRequest, NextResponse } from 'next/server'
import { prisma } from '@/lib/prisma'

interface RouteParams {
  params: { id: string }
}

export async function GET(request: NextRequest, { params }: RouteParams) {
  const { id } = params

  const user = await prisma.user.findUnique({
    where: { id },
  })

  if (!user) {
    return NextResponse.json(
      { error: 'User not found' },
      { status: 404 }
    )
  }

  return NextResponse.json({ data: user })
}

export async function DELETE(request: NextRequest, { params }: RouteParams) {
  const { id } = params

  await prisma.user.delete({ where: { id } })

  return new NextResponse(null, { status: 204 })
}

Response Format

Success Responses

// Single resource
{ "data": { "id": "123", "name": "John" } }

// Collection
{ "data": [...], "meta": { "total": 100, "page": 1, "limit": 20 } }

// Created
{ "data": { ... } } // 201 status

// No content
// Empty body, 204 status

Error Responses

// Client error
{
  "error": "Validation failed",
  "details": { ... }  // Optional
}

// Not found
{ "error": "Resource not found" }

// Unauthorized
{ "error": "Unauthorized" }

// Server error
{ "error": "Internal server error" }

Validation with Zod

Schema Definition

// lib/validations/user.ts
import { z } from 'zod'

export const createUserSchema = z.object({
  email: z.string().email('Invalid email address'),
  name: z.string().min(1, 'Name is required').max(100),
  role: z.enum(['user', 'admin']).default('user'),
})

export const updateUserSchema = createUserSchema.partial()

export type CreateUserInput = z.infer<typeof createUserSchema>
export type UpdateUserInput = z.infer<typeof updateUserSchema>

Query Parameter Validation

const querySchema = z.object({
  page: z.coerce.number().min(1).default(1),
  limit: z.coerce.number().min(1).max(100).default(20),
  search: z.string().optional(),
})

export async function GET(request: NextRequest) {
  const searchParams = Object.fromEntries(request.nextUrl.searchParams)
  const query = querySchema.parse(searchParams)
  // ...
}

Authentication

Auth Check Helper

// lib/auth.ts
import { getServerSession } from 'next-auth'
import { authOptions } from '@/app/api/auth/[...nextauth]/route'

export async function auth() {
  return getServerSession(authOptions)
}

export async function requireAuth() {
  const session = await auth()
  if (!session) {
    throw new Error('Unauthorized')
  }
  return session
}

Protected Route Pattern

export async function GET(request: NextRequest) {
  const session = await auth()

  if (!session) {
    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
  }

  // Proceed with authenticated logic
}

Server Actions

For mutations that don't need to be APIs:

// app/actions/user.ts
'use server'

import { z } from 'zod'
import { revalidatePath } from 'next/cache'
import { prisma } from '@/lib/prisma'
import { auth } from '@/lib/auth'

const updateProfileSchema = z.object({
  name: z.string().min(1).max(100),
})

export async function updateProfile(formData: FormData) {
  const session = await auth()
  if (!session?.user?.id) {
    throw new Error('Unauthorized')
  }

  const result = updateProfileSchema.safeParse({
    name: formData.get('name'),
  })

  if (!result.success) {
    return { error: result.error.flatten() }
  }

  await prisma.user.update({
    where: { id: session.user.id },
    data: result.data,
  })

  revalidatePath('/profile')
  return { success: true }
}

Rate Limiting

// lib/rate-limit.ts
import { Ratelimit } from '@upstash/ratelimit'
import { Redis } from '@upstash/redis'

const ratelimit = new Ratelimit({
  redis: Redis.fromEnv(),
  limiter: Ratelimit.slidingWindow(10, '10 s'),
})

export async function checkRateLimit(identifier: string) {
  const { success, limit, remaining } = await ratelimit.limit(identifier)
  return { success, limit, remaining }
}

// In route handler
export async function POST(request: NextRequest) {
  const ip = request.ip ?? 'anonymous'
  const { success } = await checkRateLimit(ip)

  if (!success) {
    return NextResponse.json(
      { error: 'Too many requests' },
      { status: 429 }
    )
  }
  // ...
}

Error Handling

Global Error Handler

// lib/api-error.ts
export class ApiError extends Error {
  constructor(
    public statusCode: number,
    message: string,
    public details?: unknown
  ) {
    super(message)
  }
}

export function handleApiError(error: unknown) {
  console.error('API Error:', error)

  if (error instanceof ApiError) {
    return NextResponse.json(
      { error: error.message, details: error.details },
      { status: error.statusCode }
    )
  }

  if (error instanceof z.ZodError) {
    return NextResponse.json(
      { error: 'Validation failed', details: error.flatten() },
      { status: 400 }
    )
  }

  return NextResponse.json(
    { error: 'Internal server error' },
    { status: 500 }
  )
}

Checklist

Before deploying APIs:

• All inputs validated with Zod
• Authentication checked on protected routes
• Rate limiting on public endpoints
• Proper error responses with correct status codes
• No sensitive data leaked in responses
• Logging for errors (not sensitive data)
• CORS configured if needed
• Response times acceptable