chartjs如何从数据库动态更新数据（Chartjs无法获取数据）

Question

I am so much new to chartjs and doing this current project with laravel. Now, I need to create a chart which needs to update automatically with no refresh and the data comes from mysql database.I found this kind of code online: https://codepen.io/jordanwillis/pen/bqaGRR . I tried doing this code and the output always fails me.

   // used for example purposes
function getRandomIntInclusive(min, max) {
  min = Math.ceil(min);
  max = Math.floor(max);
  return Math.floor(Math.random() * (max - min + 1)) + min;
}

// create initial empty chart
var ctx_live = document.getElementById("mycanvas");
var myChart = new Chart(ctx_live, {
  type: 'line',
  data: {
    labels: readingID,
    datasets: [{
      data: moist,
      borderWidth: 1,
      borderColor:'#00c0ef',
      label: 'liveCount',
    }]
  },
  options: {
    responsive: true,
    title: {
      display: true,
      text: "Chart.js - Dynamically Update Chart Via Ajax Requests",
    },
    legend: {
      display: false
    },
    scales: {
      yAxes: [{
        ticks: {
          beginAtZero: true,
        }
      }]
    }
  }
});

// this post id drives the example data
var readingID = [];
var moist = [];

// logic to get new data
var getData = function() {
  $.ajax({
    url: "/soildata",
    type:"GET",
    success: function(data) {
         console.log(data);
        data = JSON.parse(data);


      // process your data to pull out what you plan to use to update the chart
      // e.g. new label and a new data point

      // add new label and data point to chart's underlying data structures
      myChart.data.labels.push("ReadingID " + readingID++);
      myChart.data.datasets[0].data.push(getRandomIntInclusive(1, 25)); <<<<<-----------I DONT KNOW HOW TO PLAY ON THIS PART I GUESS THIS PART CAN MAKE MY DATABASE WORKING

      // re-render the chart
      myChart.update();
    }
  });
};

// get new data every 3 seconds
setInterval(getData, 3000);

I guess I need to make something on this function so that my data coming from my database will work properly: Chart.data.datasets[0].data.push(getRandomIntInclusive(1, 25));

Anyone?..does anyone know about this?..I am a newbie on chartjs and truely I spent weeks in solving but I guess I cant.I hope someone out there could be a help, even a different code that will solve my problem is highly accepted. Thank you for any actions that will be taken..

Answer 1

Assuming the data you get back from that ajax call is good, you should be fine with just replacing the

  myChart.data.datasets[0].data.push(getRandomIntInclusive(1, 25));

with

  myChart.data.datasets[0].data.push(data);

Of course this is dependent on the format of that data when it gets back to you.

I recommend console.log-ing that data once it gets back from the ajax to make sure it's in a format suitable for chartjs

Answer 2

Let's say, moist = [50, 30] and the content of the JSON response is as follows:

data{"id":"1" , "val":"20"}

To update moist from [50,30] to [1, 20] :

myChart.data.datasets[0].data[0] = data.id;
myChart.data.datasets[1].data[1] = data.val;
myChart.update();