Vuefire with Chart on Vue.js

I am trying to sync my chart' array data with my firebase value. Chart getting arrays for label and data. I would like to bind this Chart data value to my firebase object. Here is normal chart creation with hard coded static values:

data()
{
return {appChart: {data: {labels: ["A"], series: [[3]]}},}
},

Now, I would like to bind this value (3) with my firebase object.. Normally I can use firebase object like this with no problem:

new Vue({
   data: () => ({ myObjA: null }),
   firebase: {
      myObjA: db.ref('myObjA'),
      asObject:true
   },
  })

But I cant bind and dynamic update this myObjA with Chart array series ‘a’ like;

data()
{
return {appChart: {data: {labels: ["A"], series: [[myObjA]]}},}
},

How can I do that ?

You can change appChart to be computed properties:

export default {
  data: () => ({ myObjA: null }),
  firebase: {
    myObjA: db.ref('myObjA'),
    asObject:true
  },
  computed: {
    appChart() {
      return {
        data: {
          labels: ["A"], 
          series: [[this.myObjA]]
        }
      }
    }
  }
}
</script>