[Vuejs]-Can't set select defaut value

omg, I fixed it

created(){

  var self = this; //add self link

  Bus.$on('setCardsList', function (cards) {
    self.cards = cards;
    self.selectedCard = cards[0].id; // before this.selectedCard = cards[0].id;
       //alert(this.selectedCard) shows 2 
   });
}