keep query params on proxy

index.js

@@ -4,6 +4,7 @@ const { ServerResponse } = require('node:http')
 const WebSocket = require('ws')
 const { convertUrlToWebSocket } = require('./utils')
 const fp = require('fastify-plugin')
+const qs = require('fast-querystring')
 
 const httpMethods = ['DELETE', 'GET', 'HEAD', 'PATCH', 'POST', 'PUT', 'OPTIONS']
 const urlPattern = /^https?:\/\//
@@ -305,6 +306,20 @@ async function fastifyHttpProxy (fastify, opts) {
     wsProxy = setupWebSocketProxy(fastify, opts, rewritePrefix)
   }
 
+  function extractUrlComponents (urlString) {
+    const [path, queryString] = urlString.split('?', 2)
+    const components = {
+      path,
+      queryParams: null
+    }
+
+    if (queryString) {
+      components.queryParams = qs.parse(queryString)
+    }
+
+    return components
+  }
+
   function handler (request, reply) {
     if (request.raw[kWs]) {
       reply.hijack()
@@ -316,11 +331,11 @@ async function fastifyHttpProxy (fastify, opts) {
       }
       return
     }
-    const queryParamIndex = request.raw.url.indexOf('?')
-    let dest = request.raw.url.slice(0, queryParamIndex !== -1 ? queryParamIndex : undefined)
+    const { path, queryParams } = extractUrlComponents(request.url)
+    let dest = path
 
     if (this.prefix.includes(':')) {
-      const requestedPathElements = request.url.split('/')
+      const requestedPathElements = path.split('/')
       const prefixPathWithVariables = this.prefix.split('/').map((_, index) => requestedPathElements[index]).join('/')
 
       let rewritePrefixWithVariables = rewritePrefix
@@ -329,6 +344,9 @@ async function fastifyHttpProxy (fastify, opts) {
       }
 
       dest = dest.replace(prefixPathWithVariables, rewritePrefixWithVariables)
+      if (queryParams) {
+        dest += `?${qs.stringify(queryParams)}`
+      }
     } else {
       dest = dest.replace(this.prefix, rewritePrefix)
     }

package.json

@@ -53,6 +53,7 @@
   },
   "dependencies": {
     "@fastify/reply-from": "^9.0.0",
+    "fast-querystring": "^1.1.2",
     "fastify-plugin": "^4.5.0",
     "ws": "^8.4.2"
   },

test/test.js

@@ -6,6 +6,7 @@ const proxy = require('../')
 const got = require('got')
 const { Unauthorized } = require('http-errors')
 const Transform = require('node:stream').Transform
+const qs = require('fast-querystring')
 
 async function run () {
   const origin = Fastify()
@@ -42,6 +43,10 @@ async function run () {
     return `this is "variable-api" endpoint with id ${request.params.id}`
   })
 
+  origin.get('/variable-api/:id/endpoint-with-query', async (request, reply) => {
+    return `this is "variable-api" endpoint with id ${request.params.id} and query params ${JSON.stringify(request.query)}`
+  })
+
   origin.get('/timeout', async (request, reply) => {
     await new Promise((resolve) => setTimeout(resolve, 600))
     return 'this is never received'
@@ -890,6 +895,28 @@ async function run () {
     )
     t.equal(resultFooRoute.body, 'Hello World (foo) - lang = en')
   })
+
+  test('keep the query params on proxy', { only: true }, async t => {
+    const proxyServer = Fastify()
+
+    proxyServer.register(proxy, {
+      upstream: `http://localhost:${origin.server.address().port}`,
+      prefix: '/api/:id/endpoint',
+      rewritePrefix: '/variable-api/:id/endpoint-with-query'
+    })
+
+    await proxyServer.listen({ port: 0 })
+
+    t.teardown(() => {
+      proxyServer.close()
+    })
+
+    const firstProxyPrefix = await got(
+      `http://localhost:${proxyServer.server.address().port}/api/123/endpoint?foo=bar&foo=baz&abc=qux`
+    )
+    const queryParams = JSON.stringify(qs.parse('foo=bar&foo=baz&abc=qux'))
+    t.equal(firstProxyPrefix.body, `this is "variable-api" endpoint with id 123 and query params ${queryParams}`)
+  })
 }
 
 run()