Add API Route: $ARGUMENTS

Create a Next.js API route with proper validation, error handling, and types.

Process

1. Determine Route Structure

Parse arguments to determine:

• Route path (e.g.,

  users

  ,

  posts/[id]

  )
• HTTP methods (GET, POST, PUT, DELETE)
• Dynamic segments if any

2. Create Route File

App Router (Next.js 13+):

app/api/[route]/route.ts

Pages Router:

pages/api/[route].ts

3. Generate Route Handler

App Router template:

import { NextRequest, NextResponse } from 'next/server';

// Types
interface RequestBody {
  // define expected body shape
}

interface ResponseData {
  // define response shape
}

// GET handler
export async function GET(request: NextRequest) {
  try {
    // Implementation
    return NextResponse.json({ data: [] });
  } catch (error) {
    console.error('GET error:', error);
    return NextResponse.json(
      { error: 'Internal server error' },
      { status: 500 }
    );
  }
}

// POST handler
export async function POST(request: NextRequest) {
  try {
    const body: RequestBody = await request.json();

    // Validate
    if (!body.requiredField) {
      return NextResponse.json(
        { error: 'Missing required field' },
        { status: 400 }
      );
    }

    // Implementation
    return NextResponse.json({ success: true }, { status: 201 });
  } catch (error) {
    console.error('POST error:', error);
    return NextResponse.json(
      { error: 'Internal server error' },
      { status: 500 }
    );
  }
}

4. Add Type Definitions

Add to

types/api.ts

or

types/index.ts

:

export interface [Route]Request {
  // request body type
}

export interface [Route]Response {
  // response type
}

5. Create Tests

// __tests__/api/[route].test.ts
describe('API /api/[route]', () => {
  test('GET returns data', async () => {
    const response = await fetch('/api/[route]');
    expect(response.status).toBe(200);
  });

  test('POST validates input', async () => {
    const response = await fetch('/api/[route]', {
      method: 'POST',
      body: JSON.stringify({}),
    });
    expect(response.status).toBe(400);
  });
});

6. Validate

npm run build
npm test

Patterns

Dynamic route:

app/api/users/[id]/route.ts

Nested route:

app/api/posts/[postId]/comments/route.ts

With middleware: Add validation/auth in route or middleware.ts