"Cannot find a differ supporting object '[object Object]' of type 'object'. NgFor only supports binding to Iterables such as Arrays."

I have a problem in my GET route. As the title says. Html code:

<ion-card *ngFor="let room of rooms">

Component:

rooms : any;
this.rooms = this.roomsService.getRooms();

Provider:

  getRooms(){
return new Promise(resolve => {
  this.http.get('http://localhost:8080/api/rooms/')
    .map(res => res.json())
    .subscribe(data => {
      resolve(data);
    });
});

}

And server side:

exports.getRooms = function (req, res) {
Room.find({}, function (err, rooms) {
    if (err) {
        res.send(err);
    } else {
        res.json(rooms);
    }
});

}

What am I doing wrong?

via Chris K.