Filtering Query Parameters

The example shows how to filter query parameters from the URL using Edge Middleware.

To see how it works, check the middleware function in middleware.ts:

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import { NextRequest, NextResponse } from 'next/server'
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const allowedParams = ['allowed']
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export const config = {
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  matcher: '/',
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}
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export default function middleware(req: NextRequest) {
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  const url = req.nextUrl
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  let changed = false
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  url.searchParams.forEach((_, key) => {
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    if (!allowedParams.includes(key)) {
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      url.searchParams.delete(key)
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      changed = true
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    }
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  })
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  // Avoid infinite loop by only redirecting if the query
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  // params were changed
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  if (changed) {
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    return NextResponse.redirect(url)
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    // It's also useful to do a rewrite instead of a redirect
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    // return NextResponse.rewrite(url)
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  }
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}

Demo

https://edge-functions-query-params-filter.vercel.app

How to Use

You can choose from one of the following two methods to use this repository:

One-Click Deploy

Deploy the example using Vercel:

Clone and Deploy

Execute create-next-app with pnpm to bootstrap the example:

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pnpm create next-app --example https://github.com/vercel/examples/tree/main/edge-middleware/query-params-filter query-params-filter

Next, run Next.js in development mode:

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pnpm dev

Before URL: http://localhost:3000?a=b&allowed=test

After URL: http://localhost:3000?allowed=test

Deploy it to the cloud with Vercel (Documentation).