Fix dynamic APIs with query params (#8386)

* Fix dynamic APIs with query params

If you define a dynamic API such as

```
pages/
  api/
    [id].js
```

This api becomes available at `/api/[id]`. If you send a request with
a query parameter the value of `req.query.id` will include the query
string as well as the path parameter.

E.g. the request to `/api/2?test=123` will result in `req.query`
being

```javascript
{
  id: "2?test=123",
  test: "123",
}
```

instead of

```javascript
{
  id: "2",
  test: "123",
}
```

* Fix url parse in serverless loader

* Add serverless test

packages/next/build/webpack/loaders/next-serverless-loader.ts

@@ -50,12 +50,13 @@ const nextServerlessLoader: loader.Loader = function() {
       `
         : ``
     }
+      import { parse } from 'url'
       import { apiResolver } from 'next-server/dist/server/api-utils'
 
       export default (req, res) => {
         const params = ${
           isDynamicRoute(page)
-            ? `getRouteMatcher(getRouteRegex('${page}'))(req.url)`
+            ? `getRouteMatcher(getRouteRegex('${page}'))(parse(req.url).pathname)`
             : `{}`
         }
         const resolver = require('${absolutePagePath}')

test/integration/api-support/test/index.test.js

@@ -220,6 +220,36 @@ function runTests (serverless = false) {
     expect(data).toEqual({ post: 'post-1' })
   })
 
+  it('should work with dynamic params and search string', async () => {
+    const data = await fetchViaHTTP(
+      appPort,
+      '/api/post-1?val=1',
+      null,
+      {}
+    ).then(res => res.ok && res.json())
+
+    expect(data).toEqual({ val: '1', post: 'post-1' })
+  })
+
+  if (serverless) {
+    it('should work with dynamic params and search string like lambda', async () => {
+      await nextBuild(appDir, [])
+
+      const port = await findPort()
+      const resolver = require(join(
+        appDir,
+        '.next/serverless/pages/api/[post].js'
+      )).default
+
+      const server = createServer(resolver).listen(port)
+      const res = await fetchViaHTTP(port, '/api/post-1?val=1')
+      const json = await res.json()
+      server.close()
+
+      expect(json).toEqual({ val: '1', post: 'post-1' })
+    })
+  }
+
   it('should prioritize a non-dynamic page', async () => {
     const data = await fetchViaHTTP(
       appPort,

test/integration/production/pages/api/[post]/index.js

+export default ({ query }, res) => {
+  res.status(200).json(query)
+}

test/integration/production/test/index.test.js

@@ -233,6 +233,14 @@ describe('Production Usage', () => {
       const body = await res.text()
       expect(body).toEqual('API hello works')
     })
+
+    it('should work with dynamic params and search string', async () => {
+      const url = `http://localhost:${appPort}/api/post-1?val=1`
+      const res = await fetch(url)
+      const body = await res.json()
+
+      expect(body).toEqual({ val: '1', post: 'post-1' })
+    })
   })
 
   describe('With navigation', () => {

test/integration/serverless/pages/api/dynamic/[path]/index.js

+export default ({ query }, res) => {
+  res.json(query)
+}

test/integration/serverless/pages/api/posts/[id].js

-export default (req, res) => {
-  res.json({ post: req.query.id })
+export default ({ query }, res) => {
+  res.json(query)
 }

test/integration/serverless/test/index.test.js

@@ -121,8 +121,28 @@ describe('Serverless', () => {
 
   it('should reply on dynamic API request successfully', async () => {
     const result = await renderViaHTTP(appPort, '/api/posts/post-1')
-    const { post } = JSON.parse(result)
-    expect(post).toBe('post-1')
+    const { id } = JSON.parse(result)
+    expect(id).toBe('post-1')
+  })
+
+  it('should reply on dynamic API request successfully with query parameters', async () => {
+    const result = await renderViaHTTP(appPort, '/api/posts/post-1?param=val')
+    const { id, param } = JSON.parse(result)
+    expect(id).toBe('post-1')
+    expect(param).toBe('val')
+  })
+
+  it('should reply on dynamic API index request successfully', async () => {
+    const result = await renderViaHTTP(appPort, '/api/dynamic/post-1')
+    const { path } = JSON.parse(result)
+    expect(path).toBe('post-1')
+  })
+
+  it('should reply on dynamic API index request successfully with query parameters', async () => {
+    const result = await renderViaHTTP(appPort, '/api/dynamic/post-1?param=val')
+    const { path, param } = JSON.parse(result)
+    expect(path).toBe('post-1')
+    expect(param).toBe('val')
   })
 
   it('should 404 on API request with trailing slash', async () => {