angular js post request to nodejs json. key undefined express 4

Your Angular code is sending JSON data, but your Express app is parsing it as URL encoded data.

You probably have something like this in your Express app:

var bodyParser = require('body-parser');
...
app.use(bodyParser.urlencoded());

That last line should be:

app.use(bodyParser.json());

You did not well explain the problem , please next time try to post a bigger part of your code so we could understand what you wanted to do / to say .

To answer your question i will copy/paste a part of my code that enable you to receive a post request from your frontend application(angularJS) to your backend application (NodeJS), and another function that enable you to do the inverse send a post request from nodeJS to another application (that might consume it):

1) receive a request send from angularJS or whatever inside your nodeJS app

    //Import the necessary libraries/declare the necessary objects
var express = require("express");
var myParser = require("body-parser");
var app = express();
// we will need the following imports for the inverse operation
var https = require('https')
var querystring = require('querystring')

      // we need these variables for the post request:


      var Vorname ;
      var Name ;
      var e_mail ;
      var Strasse ;


  app.use(myParser.urlencoded({extended : true}));
  // the post request is send from http://localhost:8080/yourpath
  app.post("/yourpath", function(request, response ) {
      // test the post request
      if (!request.body) return res.sendStatus(400);

      // fill the variables with the user data
       Vorname =request.body.Vorname;
       Name =request.body.Name;
       e_mail =request.body.e_mail;
       Strasse =request.body.Strasse;      
      response.status(200).send(request.body.title);

});

2) Do the inverse send a POST request from a nodeJS application to another application

    function sendPostRequest()
    {
        // prepare the data that we are going to send to anymotion  
        var jsonData = querystring.stringify({
                "Land": "Land",
                "Vorname": "Vorname",
                "Name": "Name",
                "Strasse": Strasse,
            });
        var post_options = {
            host: 'achref.gassoumi.de',
            port: '443',
            method: 'POST',
            path: '/api/mAPI',
            headers: {
                'Content-Type': 'application/x-www-form-urlencoded',
                'Content-Length': jsonData.length
            }
        };
        // request object
            var post_req = https.request(post_options, function(res) {
            var result = '';
            res.on('data', function (chunk) {
                result += chunk;
                console.log(result);
            });
            res.on('end', function () {
            // show the result in the console : the thrown result in response of our post request
            console.log(result);
        });
        res.on('error', function (err) {
            // show possible error while receiving the result of our post request
            console.log(err);
        })
        });
        post_req.on('error', function (err) {
            // show error if the post request is not succeed
            console.log(err);
        });
        // post the data
        post_req.write(jsonData);
        post_req.end(); 
// ps : I used a https post request , you could use http if you want but you have to change the imported library and some stuffs in the code
    }

So finally , I hope this answer will helps anyone who is looking on how to get a post request in node JS and how to send a Post request from nodeJS application.

For further details about how to receive a post request please read the npm documentation for body-parser library : npm official website documentation

I hope you enjoyed this and Viel spaß(have fun in german language).