Calling an Api to get the values and putting them in the List but the list in data function is not being updated.

created() {
  // API CALL FOR BARCHAR
  var getStandardBarchart = async() => {
  //var currentarray =[]

  // API CALL TO KEIKAI for BARCGARTS
  var myHeaders = new Headers();
   myHeaders.append("Content-Type", "application/json");
   //var raw = JSON.stringify({"input_values": input_values, "output_values": output_values});
   var raw = JSON.stringify({"input_values": {},"output_values": [ "barchart1","barchart2","barchart3","barchart4","barchart5","barchart6","barchart7","barchart8"  ]});

   var requestOptions = {
     method: 'POST',
     headers: myHeaders,
     body: raw,
     redirect: 'follow'
   };


   await fetch("/api", requestOptions)
     .then(response => response.json())
     .then(result => {
        var barChart = [];

        //var value
        Object.keys(result).forEach(function(key) {
        let specificValue = parseInt(result[key])
          barChart.push(specificValue) 
        })
        console.log(barChart)
        console.log(this.Agricultural_production_Animal_production_Cattle[1].imagecontent.barchart1.values[0][2])
       // this.Agricultural_production_Animal_production_Cattle[1].imagecontent.barchart1.values[0][1]=15

        // this.Agricultural_production_Animal_production_Cattle[1].imagecontent.barchart1.values[0] = barChart.splice(0, 4);
        // this.Agricultural_production_Animal_production_Cattle[1].imagecontent.barchart1.values[1] = barChart.splice(0, 4);


      })
     .catch(error => console.log('error', error));



 }

getStandardBarchart()
}

What I want is that the values in the data function should be updated by the barchart[] list. But if I push something in list before api or give some default value to the list it is not undefined in Values : [barchart[0]] gives undefined.

data:function(){
  {imagecontent:
    
   {barchart1:{barid: "bar_Agricultural_production_Animal_production_Cattle",names:["sdjhfb", "derfgas", "Pdft", "dfdfs", "dfsdfat"],
   values:[[barchart[0], 10, 5, 150],[87, 80, 25, 35]],
   textxaxis:["future", "present"] }}
   }]
  }
}