如下filters如何调用method中的padDate并且传值呢？
filters: {

    formatDate: function(value) {
        let _this = this;
        let date = new Date(value);
        let year = date.getFullYear();
        let month = padDate(date.getMonth()+1);
        let day = padDate(date.getDate());
        let hour = padDate(date.getHours());
        let minutes = padDate(date.getMinutes());
        let seconds = padDate(date.getSeconds());
        return year +'-'+month +'-'+day+''+hour+':'+minutes+':'+seconds;
    }

},
methods: {

  padDate(value){
      return value <10?'0'+value :value;
  }

}