CODEWITHSUNDEEP
javascriptarraysangularchart.js
Garrett
Garrett

Reputation: 1792

Using data from API with Chart JS

I am getting data from an api and then reformatting part of it into an array using .map(), I am successfully able to do this, but when it comes time to pass it into Chart JS as data it does work. I am able to pass in a normal, hard coded, array but not my own data...

I tried using an Angular directive (NG2-Charts) to help out thinking maybe that was the problem, but that doesn't work either...

Component.ts: ... Other variable and stuff up here...

getStockData() {
    this.stocksService.getStockData()
      .subscribe(
        (response) => {
          for(var i = 0; i < response.length; i++) {
            this.stockOpen.push(response[i]['open']);
          }
          console.log('after loop: ', this.stockOpen);
        },
        (error) => console.error(error)
      );
      console.log('real: ', this.stockOpen);
      console.log('test: ', this.testData);
  }

  // Chart JS version
  buildStockChart() {
    var ctx = document.querySelector("#chart");
    this.chart = new Chart(ctx, {
      type: 'bar',
      data: {
        labels: [1,2,3,4,5],
        datasets: [
          { 
            data: this.stockOpen,
            borderColor: "#3cba9f",
            fill: false
          }
        ]
      },
      options: {
        legend: {
          display: false
        },
        scales: {
          xAxes: [{
            display: true
          }],
          yAxes: [{
            display: true
          }],
        }
      }
    });
  }

  // NG2-Charts version
  public lineChartData:Array<any> = [
    {data: this.testData},
  ];
  public lineChartLabels:Array<any> = ['January', 'February', 'March', 'April', 'May', 'June', 'July'];
  public lineChartOptions:any = {
    responsive: true
  };

Result from console.log(): enter image description here

Upvotes: 3

Views: 17795

Answers (3)

Pipo
Pipo

Reputation: 5073

As @Joseph Agbing, I was unable to get it work with angular 7. I'm now using chart.js only 

npm install chart.js --save

with into my someChart.component.html

<div style="display: block"><!--Mandatory div including chart--> <canvas id="canvas">{{chart}}</canvas> </div>

into my someChart.component.ts

called from my httpClient.post(...).subscribe(lData => (setChartDataFromEntities(lDataProcessed), ...)

import { Chart } from 'chart.js';

export class someClass {

/**
* 
* @param aDate 
* @param aChargeUnitArray 
*/
setChartDataFromEntities( aDate: Date, aChargeUnitArray: ChargeUnit[] ){
    console.debug('setChartDataFromEntities->', aChargeUnitArray)
    let lChartDataArray = []
    let lChartDataLineDataArray: Array<Number> = []
    let lChartLabelsArray: string[] = []
    let l_s: string
    aChargeUnitArray.forEach(element => {
        lChartDataLineDataArray.push(element.charge)
        lChartLabelsArray.push(MiscHelper.dateTimeHMSForChart(element.timestamp))
    });
    lChartDataArray.push(
        {
            data: lChartDataLineDataArray,
            label: MiscHelper.dateForGui(aDate),
        }
    )

    this.chart = new Chart('canvas', {
    type: 'line',
    data: {
        labels: lChartLabelsArray,
        datasets: lChartDataArray
    },
    options: {
        legend: {
            display: false
        },
        scales: {
        xAxes: [{
            display: true
        }],
        yAxes: [{
            display: true
        }],
        }
    }
    });    

    this.statusMessage = 'Chart loaded'
}

hope it helps somebody more than the day I wasted trying to get it work...

Upvotes: 0

Joseph Agbing
Joseph Agbing

Reputation: 81

i also have same problem with chart JS on angular so i force to use another chart. im now using angular 2 chart js.

i think the problem here is the delay of data fetch by API, the CHART component is already render on html view but the data is still not fetch by the API service.

try to add this code on your code block. This will handle the data if API service data is available. ()=>{this.buildStockChart();}

 this.stocksService.getStockData()
      .subscribe(
        (response) => {
          for(var i = 0; i < response.length; i++) {
            this.stockOpen.push(response[i]['open']);
          }
          console.log('after loop: ', this.stockOpen);
        },
        ()=>{
        this.buildStockChart();
        }
      );
      console.log('real: ', this.stockOpen);
      console.log('test: ', this.testData);
  }

This chart is easy to manage for dynamic instances.

Hope this chart will work on you.

https://www.npmjs.com/package/angular2-chartjs

Upvotes: 3

Bruno
Bruno

Reputation: 389

When are you calling the buildStockChart() method?

You should call it right after the for loop into the callback you pass to the subscribe method, since that's the moment when this.stockOpen is populated (before that moment it will be empty as you are seeing in the console).

Upvotes: 0

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