[#437] dynamic value generation of option parseReqBody

README.md

@@ -407,6 +407,19 @@ app.use('/proxy', proxy('www.google.com', {
   parseReqBody: false
 }));
 ```
+You can use function instead of boolean value for dynamic value generation based on request
+
+```js
+app.use('/proxy', proxy('www.google.com', {
+  parseReqBody: function (proxyReq) {
+    if (proxyReq.headers["content-type"] === "application/json") {
+      return true;
+    } else {
+      return false;
+    }
+  }
+}));
+``` 
 
 #### reqAsBuffer
 

app/steps/buildProxyReq.js

@@ -9,7 +9,8 @@ function buildProxyReq(Container) {
   var options = Container.options;
   var host = Container.proxy.host;
 
-  var parseBody = (!options.parseReqBody) ? Promise.resolve(null) : requestOptions.bodyContent(req, res, options);
+  var parseReqBody = (typeof options.parseReqBody === 'function') ? options.parseReqBody(req) : options.parseReqBody;
+  var parseBody = (!parseReqBody) ? Promise.resolve(null) : requestOptions.bodyContent(req, res, options);
   var createReqOptions = requestOptions.create(req, res, options, host);
 
   return Promise

app/steps/sendProxyRequest.js

@@ -36,8 +36,9 @@ function sendProxyRequest(Container) {
 
     proxyReq.on('error', reject);
 
+    var parseReqBody = (typeof options.parseReqBody === 'function') ? options.parseReqBody(req) : options.parseReqBody;
     // this guy should go elsewhere, down the chain
-    if (options.parseReqBody) {
+    if (parseReqBody) {
     // We are parsing the body ourselves so we need to write the body content
     // and then manually end the request.
 

lib/requestOptions.js

@@ -86,6 +86,7 @@ function createRequestOptions(req, res, options) {
 
 function bodyContent(req, res, options) {
   var parseReqBody = isUnset(options.parseReqBody) ? true : options.parseReqBody;
+  parseReqBody = (typeof parseReqBody === 'function') ? parseReqBody(req) : options.parseReqBody;
 
   function maybeParseBody(req, limit) {
     if (req.body) {

test/bodyEncoding.js

@@ -64,7 +64,7 @@ describe('body encoding', function () {
 
   });
 
-  describe('when user sets parseReqBody', function () {
+  describe('when user sets parseReqBody as bool', function () {
     it('should not parse body', function (done) {
       var filename = os.tmpdir() + '/express-http-proxy-test-' + (new Date()).getTime() + '-png-transparent.png';
       var app = express();
@@ -140,6 +140,50 @@ describe('body encoding', function () {
   });
 
 
+  describe('when user sets parseReqBody as function', function () {
+    it('should not parse body with form-data content', function (done) {
+      var filename = os.tmpdir() + '/express-http-proxy-test-' + (new Date()).getTime() + '-png-transparent.png';
+      var app = express();
+      app.use(proxy('localhost:8109', {
+        parseReqBody: (proxyReq) => proxyReq.headers['content-type'].includes('application/json'),
+        proxyReqBodyDecorator: function (bodyContent) {
+          assert(!bodyContent, 'body content should not be parsed.');
+          return bodyContent;
+        }
+      }));
+
+      fs.writeFile(filename, pngData, function (err) {
+        if (err) { throw err; }
+        request(app)
+          .post('/post')
+          .attach('image', filename)
+          .end(function (err) {
+            fs.unlinkSync(filename);
+
+            done(err);
+          });
+      });
+    });
+    it('should parse body with json content', function (done) {
+      var app = express();
+      app.use(proxy('localhost:8109', {
+        parseReqBody: (proxyReq) => proxyReq.headers['content-type'].includes('application/json'),
+        proxyReqBodyDecorator: function (bodyContent) {
+          assert(bodyContent, 'body content should be parsed.');
+          return bodyContent;
+        }
+      }));
+
+      request(app)
+        .post('/post')
+        .send({ some: 'json' })
+        .end(function (err) {
+          done(err);
+        });
+    });
+  });
+
+
   describe('when user sets reqBodyEncoding', function () {
     it('should set the accepts-charset header', function (done) {
       var app = express();