// fetching datas
  methods: {
    getDataAgents : function(){
      let items = this
      let url = 'http://localhost:3000/stokiest'
      axios.get(url)
      .then(function(res){
        items.agents = res.data

        console.log(res.data)
      })
      .catch(function(err) {
        console.log(err)
      })
    }
  },
  getByid : function(id){
    let item = this;
    let url = 'http://localhost:3000/stokiest/' + id
    axios.get(url)
    then(function(res) {
      console.log(res)
    })
  }
};

component

  <v-btn color="success" v-on:click="getByid">Get data Agent</v-btn>