[Vuejs]-How to populate nested select options with values from database one after another

This solves the problem

  beforeMount: function() {
    fetch("https://www.example.com/loc/instant")
      .then(result => result.json())
      .then(result => {
       this.result=result;

        this.selected = this.result[0].cityid,

        this.ilceleriGetir();
        this.selected2 = this.result[0].countyid

      })
  },