Merge remote-tracking branch 'origin/master'

Author: mredele

src/lambda-wrapper.js

@@ -5,12 +5,12 @@ const { Request } = require('./request');
  * API Gateway handler generator for Lambda
  *
  * @param {object} router Express compatible router instance
- * @param {function} finalHandler Process response before sending it. Function params: err, out, req, res
+ * @param {function} onFinished Last callback before output gets send. Function params: out, req, res
  * @return {function} Lambda handler for API gateway events
  * @public
  */
 
-exports.ApiGatewayHandler = (router, finalHandler) => {
+exports.ApiGatewayHandler = (router, onFinished) => {
   /**
    * Lambda Handler for API Gateway invocations
    *
@@ -19,28 +19,28 @@ exports.ApiGatewayHandler = (router, finalHandler) => {
    * @return {promise} Returns undefined if callback param is set. Return a promise if callback param is undefined.
    */
   return handleApiGatewayEvent = (event, context) => {
-    return new Promise((resolve, reject) => {
-      try {
-        const req = new Request(event);
-        const res = req.res = new Response(req, out => {
-          resolve(finalHandler(null, out, req, res))
-        });
-
-        // run middleware managed by router
-        router(req, res, async err => {
-          if (err) {
-            // unexpected errors should be handled by final handler
-            resolve(finalHandler(err, null, req, res))
-          } else if (res.writableEnded) {
-            console.error('ERROR: next() should not be used after res.send() within routing middleware');
-          } else {
-            // expected error
-            res.status(404).send('Not found');
-          }
-        })
-      } catch (error) {
-        resolve(finalHandler(error, null, null, null))
-      }
+    return new Promise(resolve => {
+      const req = new Request(event);
+      const res = req.res = new Response(req, async out => {
+        // run and wait for onFinished callback
+        if (onFinished) try {
+          out = await onFinished(out, req, res)
+        } catch (err) {
+          console.error('Error in onFinished callback: ', err)
+        }
+        // resolve promise even if onFinished callback errors out
+        resolve(out)
+      });
+      router(req, res, err => { 
+        // handle generic routing errors
+        // use error handling middleware for more granular control
+        if (err) {
+          console.error('ERROR: ', err)
+          res.status(500).send('Server error')
+        } else {
+          res.status(404).send('Not found');
+        }
+      })
     })    
   }
-}
+}

src/lambda-wrapper.spec.js

@@ -2,10 +2,6 @@ const { ApiGatewayHandler } = require('./lambda-wrapper');
 const Router = require('router');
 const bodyParser = require('body-parser');
 
-function finalHandlerPassTrough (err, out, req, res) {
-  return out
-}
-
 describe('Lambda Wrapper', () => {
   const proxyRequest = {
     body: null,
@@ -28,7 +24,7 @@ describe('Lambda Wrapper', () => {
     router.use((req, res) => {
       res.json({a: 1});
     })
-    const lambdaHandler = ApiGatewayHandler(router, finalHandlerPassTrough);
+    const lambdaHandler = ApiGatewayHandler(router);
     const proxyRequest = {
       body: '',
       headers: {},
@@ -63,7 +59,7 @@ describe('Lambda Wrapper', () => {
     router.use((req, res) => {
       res.json(req.body);
     })
-    const lambdaHandler = ApiGatewayHandler(router, finalHandlerPassTrough);
+    const lambdaHandler = ApiGatewayHandler(router);
 
     const requestObject = JSON.stringify({a: 1});
     const proxyRequest = {
@@ -108,7 +104,7 @@ describe('Lambda Wrapper', () => {
     router.use((req, res) => {
       res.json({b: req.fromFirstEndpoint});
     })
-    const lambdaHandler = ApiGatewayHandler(router, finalHandlerPassTrough);
+    const lambdaHandler = ApiGatewayHandler(router);
 
     const result = await lambdaHandler(proxyRequest, {});
 
@@ -128,11 +124,13 @@ describe('Lambda Wrapper', () => {
     router.use((req, res, next) => {
       throw Error('test');
     })
-
-    const lambdaHandler2 = ApiGatewayHandler(router, err => {
+    router.use((err, req, res, next) => {
       expect(err).toEqual(Error('test'));
+      next();
     })
-    await lambdaHandler2(proxyRequest, {})
+    const lambdaHandler = ApiGatewayHandler(router)
+    const out = await lambdaHandler(proxyRequest, {})
+    console.log(out)
   })
 
   it('should handle next(error)', async () => {
@@ -142,11 +140,12 @@ describe('Lambda Wrapper', () => {
     router.use((req, res, next) => {
       next('test');
     })
-    const lambdaHandler = ApiGatewayHandler(router, err => {
+    router.use((err, req, res, next) => {
       expect(err).toEqual('test');
-    });
+      next();
+    })
+    const lambdaHandler = ApiGatewayHandler(router);
     await lambdaHandler(proxyRequest, {})
-
   })
 
   it('GET with path', async () => {
@@ -160,7 +159,7 @@ describe('Lambda Wrapper', () => {
       res.json({a: req.fromFirstEndpoint, b: 2});
     });
 
-    const lambdaHandler = ApiGatewayHandler(router, finalHandlerPassTrough);
+    const lambdaHandler = ApiGatewayHandler(router);
     const proxyRequest = {
       body: '',
       headers: {},
@@ -199,7 +198,7 @@ describe('Lambda Wrapper', () => {
       res.json({a: req.foo, b: 2});
     });
 
-    const lambdaHandler = ApiGatewayHandler(router, finalHandlerPassTrough);
+    const lambdaHandler = ApiGatewayHandler(router);
 
     const result = await lambdaHandler(proxyRequest, {});
     expect(result).toEqual({
@@ -223,7 +222,7 @@ describe('Lambda Wrapper', () => {
     const router = Router()
     router.use('/testing', subRouter)
 
-    const lambdaHandler = ApiGatewayHandler(router, finalHandlerPassTrough);
+    const lambdaHandler = ApiGatewayHandler(router);
 
     let request = {}
     Object.assign(request, proxyRequest)

src/response.js

@@ -33,10 +33,12 @@ class Response extends EventEmitter {
     if (this.writableEnded) throw new Error('write after end')
     this.writableEnded = true
     this.emit('finished')
+    const body = this[AWS_RES_BODY]
+    const bodyStr = typeof body === 'string' ? body : JSON.stringify(body)
     const apiGatewayResult = {
       statusCode: this.statusCode,
       headers: this[AWS_RES_HEADERS],
-      body: this[AWS_RES_BODY]
+      body: bodyStr
     }
     this[ON_FINISHED](apiGatewayResult)
   }