NodeJs - Retrieve user information from JWT token?

Issue

Node and Angular. I have a MEAN stack authentication application where I am setting a JWT token on successful login as follows, and storing it in a session in the controller. Assigning the JWT token to config.headers through service interceptor:

var token = jwt.sign({id: user._id}, secret.secretToken, { expiresIn: tokenManager.TOKEN_EXPIRATION_SEC });
            return res.json({token:token});

authservice.js Interceptor(omitted requestError,response and responseError):

authServices.factory('TokenInterceptor', ['$q', '$window', '$location','AuthenticationService',function ($q, $window, $location, AuthenticationService) {
        return {
            request: function (config) {
                config.headers = config.headers || {};
                if ($window.sessionStorage.token) {
                    config.headers.Authorization = 'Bearer ' + $window.sessionStorage.token;
                }
                return config;
            }               
        };
    }]);

Now I wanted to get the logged in user details from the token, How can I do that? I tried as follows, not working. When I log the error from Users.js file it's saying "ReferenceError: headers is not defined"

authController.js:

$scope.me = function() {
    UserService.me(function(res) {
      $scope.myDetails = res;
    }, function() {
      console.log('Failed to fetch details');
      $rootScope.error = 'Failed to fetch details';
    })
  };

authService.js:

authServices.factory('UserService',['$http', function($http) {
  return {        
    me:function() {
    return $http.get(options.api.base_url + '/me');
    }
  }
}]);

Users.js (Node):

 exports.me = function(req,res){
    if (req.headers && req.headers.authorization) {
        var authorization =req.headers.authorization;
        var part = authorization.split(' ');
        //logic here to retrieve the user from database
    }
    return res.send(200);
}

Do i have to pass the token as a parameter too for retrieving the user details? Or save the user details in a separate session variable as well?

Solution

First of all, it is a good practice to use Passport middleware for user authorization handling. It takes all the dirty job of parsing your request and also provides many authorization options. Now for your Node.js code. You need to verify and parse the passed token with jwt methods and then find the user by id extracted from the token:

exports.me = function(req,res){
    if (req.headers && req.headers.authorization) {
        var authorization = req.headers.authorization.split(' ')[1],
            decoded;
        try {
            decoded = jwt.verify(authorization, secret.secretToken);
        } catch (e) {
            return res.status(401).send('unauthorized');
        }
        var userId = decoded.id;
        // Fetch the user by id 
        User.findOne({_id: userId}).then(function(user){
            // Do something with the user
            return res.send(200);
        });
    }
    return res.send(500);
}

Answered By - Constantine Poltyrev