Reactjs - How to automatically update chart data in React components?

Darkside
September 18, 2023
185 views
1 vote
2 Answers

How can we achieve automatic updating of chart data in a chart component wrapped with React?

For example, the data I requested from backend will change and I want to update it whever it changes.

I tried to look up the documents of some chart library, but didn’t find the answer.

Answers

If you are passing a state with data to a line chart or any other chart from react-chartjs-2, it gets automatically updated.
Here is a basic example, hopefully, it makes sense for you.

import React, { useState, useEffect } from 'react';
import { Line } from 'react-chartjs-2';

function ChartComponent() {
  const [chartData, setChartData] = useState({
    labels: [],
    datasets: [
      {
        label: 'Data Series',
        data: [],
        borderColor: 'rgba(75,192,192,1)',
        borderWidth: 1,
        fill: false,
      },
    ],
  });

  useEffect(() => {
    // Function to fetch data from your backend
    const fetchData = async () => {
      try {
        const response = await fetch('your-backend-endpoint');
        const data = await response.json();

        // Extract relevant data from the response and update the chartData
        const newLabels = data.map(entry => entry.label);
        const newDataPoints = data.map(entry => entry.value);

        setChartData({
          labels: newLabels,
          datasets: [
            {
              ...chartData.datasets[0], // Keep other properties as they are
              data: newDataPoints,
            },
          ],
        });
      } catch (error) {
        console.error('Error fetching data:', error);
      }
    };

    fetchData();
  }, []);

  return (
    <div>
      <Line data={chartData} />
    </div>
  );
}

export default ChartComponent;

- xuanhun
- September 7, 2023 at 5:14 am
- 0 votes
0
Solution

In VChart, you can update the chart by calling either updateSpec or updateData.

To update the chart data, you can save the chart instance using ref when initializing the chart instance in a React component. Then, use useEffect to set the dependencies to the data that needs to be updated, and call the chart instance’s updateData method in the callback function.

VChart also provides a React-VChart wrapper:

https://www.visactor.io/vchart/guide/tutorial_docs/Cross-terminal_and_Developer_Ecology/react

You can refer to the code example below to update the chart data using React-VChart.

Code Example

Clicking the "Update the data of bar chart" button allows for the updating of the chart’s data.
```
import "./styles.css";
import { BarChart } from "./BarChart";
import { LineChart } from "./LineChart";
import { AreaChart } from "./AreaChart";
import { getBarData } from "./bar-data";
import { useState } from "react";

const colorMaps = {
  default: [
    "#6690F2",
    "#70D6A3",
    "#B4E6E2",
    "#63B5FC",
    "#FF8F62",
    "#FFDC83",
    "#BCC5FD",
    "#A29BFE",
    "#63C4C7",
    "#F68484"
  ],
  red: [
    "#c12e34",
    "#e6b600",
    "#0098d9",
    "#2b821d",
    "#005eaa",
    "#339ca8",
    "#cda819",
    "#32a487"
  ]
};

export default function App() {
  const [barData, setBarData] = useState<any[]>(getBarData());
  const [colors, setColors] = useState<string[]>(colorMaps.default);
  const handleUpdateBarData = () => {
    setBarData(getBarData());
  };

  const handleUpdateColors = () => {
    if (colors === colorMaps.default) {
      setColors(colorMaps.red);
    } else {
      setColors(colorMaps.default);
    }
  };

  return (
    <div className="App">
      <div>
        <img src="https://lf9-dp-fe-cms-tos.byteorg.com/obj/bit-cloud/logo_500_200_light.png" />
      </div>
      <button onClick={handleUpdateBarData}>
        Update the data of bar chart
      </button>

      <button onClick={handleUpdateColors}>update colors</button>

      <h2>A Bar Chart</h2>

      <BarChart data={barData} colors={colors} />

      <h2>A Line Chart</h2>
      <LineChart colors={colors} />

      <h2>A Area Chart</h2>
      <AreaChart colors={colors} />
    </div>
  );
}
```
Results

Online demo：https://codesandbox.io/s/visactor-vchart-react-demo-forked-jsqqjj

Related Documentation

react-vchart Tutorial：https://www.visactor.io/vchart/guide/tutorial_docs/Cross-terminal_and_Developer_Ecology/react

github：https://github.com/VisActor/VChart
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