Update Next.js Guide: Use Full Confirmation URL in successUrl for Checkout Route

[amittam104]

Documentation Update: Invalid URL Error in Next.js Guide for Checkout

Current Status

The current code in the Next.js integration guide uses a relative URL for the successUrl:

// src/app/checkout/route.ts
import { Checkout } from '@polar-sh/nextjs'

export const GET = Checkout({
  accessToken: process.env.POLAR_ACCESS_TOKEN!,
  successUrl: '/confirmation',
  server: 'sandbox', // Use this option if you're using the sandbox environment - else use 'production' or omit the parameter
});

This throws the following error:

⨯ [TypeError: Invalid URL] {
  code: 'ERR_INVALID_URL',
  input: '/confirmation'
}

Expected Behavior

The successUrl should accept a valid, absolute URL string — not a relative one.

Recommended Fix

Update the successUrl to use a full absolute URL instead of a relative path. The updated example should look like this:

// src/app/checkout/route.ts
import { Checkout } from '@polar-sh/nextjs'

export const GET = Checkout({
  accessToken: process.env.POLAR_ACCESS_TOKEN!,
  successUrl: 'https://your-domain.com/confirmation', // Use localhost in development, swap with your production URL in production
  server: 'sandbox', // Use this option if you're using the sandbox environment - else use 'production' or omit the parameter
});

This resolves the Invalid URL error.