Angular Generating access token

Troubleshooting
1

Hello guys,

I am playing with ionic and angular and I am stuck with http post. After sending post, an error come with
https://api.particle.io/oauth/token 400 (Bad Request)

data:  Object
 error: "invalid_request"
error_description :"Invalid or missing grant_type parameter"

but it is included.

$scope.getToken = function(){
     var config = {
         'method': 'POST',
         'url': 'https://api.particle.io/oauth/token',
         'data':{
            'username':'user@gmail.com',
            'password':'userpassword',
            'grant_type':'password'
          },
          'headers':{
             'Content-Type': 'application/x-www-form-urlencoded'
          }   
     }
        $http(config).then(function (response) {
            console.log(response);
            if (response.data)
            console.log(response.data);
        }, function (response) {
            console.log(response);
        });
}

Thank you for help.

2

@bryce