Merge pull request #41 from panva/master

support multiple headers with the same name

Author: brettstack

README.md

@@ -80,5 +80,4 @@ app.use(awsServerlessExpressMiddleware.eventContext())
  - May be more expensive for high-traffic apps
  - Cannot use native libraries (aka [Addons](https://nodejs.org/api/addons.html)) unless you package your app on an EC2 machine running Amazon Linux
  - Stateless only
- - Multiple headers with same name not currently supported
  - API Gateway has a timeout of 30 seconds, and Lambda has a maximum execution time of 5 minutes.

__tests__/index.js

@@ -84,34 +84,55 @@ test('getSocketPath', () => {
     expect(socketPath).toEqual('/tmp/server0.sock')
 })
 
-describe('forwardResponseToApiGateway: content-type encoding', () => {
-    const PassThrough = require('stream').PassThrough
-
-    class MockResponse extends PassThrough {
-        constructor(statusCode, headers, body) {
-            super()
-            this.statusCode = statusCode
-            this.headers = headers || {}
-            this.write(body)
-            this.end()
-        }
+const PassThrough = require('stream').PassThrough
+
+class MockResponse extends PassThrough {
+    constructor(statusCode, headers, body) {
+        super()
+        this.statusCode = statusCode
+        this.headers = headers || {}
+        this.write(body)
+        this.end()
     }
+}
 
-    class MockServer {
-        constructor(binaryTypes) {
-            this._binaryTypes = binaryTypes || []
-        }
+class MockServer {
+    constructor(binaryTypes) {
+        this._binaryTypes = binaryTypes || []
     }
+}
 
-    class MockContext {
-        constructor(resolve) {
-            this.resolve = resolve
-        }
-        succeed(successResponse) {
-            this.resolve(successResponse)
-        }
+class MockContext {
+    constructor(resolve) {
+        this.resolve = resolve
+    }
+    succeed(successResponse) {
+        this.resolve(successResponse)
     }
+}
 
+describe('forwardResponseToApiGateway: header handling', () => {
+  test('multiple headers with the same name get transformed', () => {
+      const server = new MockServer()
+      const headers = {'foo': ['bar', 'baz']}
+      const body = 'hello world'
+      const response = new MockResponse(200, headers, body)
+      return new Promise(
+          (resolve, reject) => {
+              const context = new MockContext(resolve)
+              awsServerlessExpress.forwardResponseToApiGateway(
+                  server, response, context)
+          }
+      ).then(successResponse => expect(successResponse).toEqual({
+          statusCode: 200,
+          body: body,
+          headers: { Foo: 'bar', fOo: 'baz' },
+          isBase64Encoded: false
+      }))
+  })
+})
+
+describe('forwardResponseToApiGateway: content-type encoding', () => {
     test('content-type header missing', () => {
         const server = new MockServer()
         const headers = {'foo': 'bar'}

index.js

@@ -14,6 +14,7 @@
  */
 'use strict'
 const http = require('http')
+const binarycase = require('binary-case')
 
 function getPathWithQueryStringParams(event) {
     const queryStringKeys = Object.keys(event.queryStringParameters || {})
@@ -55,9 +56,16 @@ function forwardResponseToApiGateway(server, response, context) {
             const statusCode = response.statusCode
             const headers = response.headers
 
+            // HACK: modifies header casing to get around API Gateway's limitation of not allowing multiple
+            // headers with the same name, as discussed on the AWS Forum https://forums.aws.amazon.com/message.jspa?messageID=725953#725953
             Object.keys(headers)
                 .forEach(h => {
-                    if(Array.isArray(headers[h])) headers[h] = headers[h].join(',')
+                    if(Array.isArray(headers[h])) {
+                      headers[h].forEach((value, i) => {
+                        headers[binarycase(h, i + 1)] = value
+                      })
+                      delete headers[h]
+                    }
                 })
 
             const contentType = headers['content-type']

package.json

@@ -32,5 +32,8 @@
   },
   "scripts": {
     "test": "jest"
+  },
+  "dependencies": {
+    "binary-case": "^1.0.0"
   }
 }