FormData factory to transform your requests

formdata.ctrl.js

$scope.submit = function submit() {
  return $http({
    method: 'POST', 
    url: '/your/url',
    headers: {
      'Content-Type': 'multipart/form-data'
    },
    data: {
	file: $scope.file
    },
    transformRequest: formDataObject
  });
};

formdata.factory.js

var app = angular.module('myApp', []);

app.factory('formDataObject', function() {
  return function(data) {
    var fd = new FormData();
    angular.forEach(data, function(value, key) {
      fd.append(key, value);
    });
    return fd;
  };
});

See http://badwing.com/multipart-form-data-ajax-uploads-with-angularjs/ for more information