Using Firebase about chartjs-plugin-streaming HOT 5 CLOSED

Is this a time-series dataset? Is the value field in child nodes of transactions updated periodically but they don't contain timestamps?

As the onRefresh callback in this plugin only allows pull-based ingestion but Firebase event listeners are push-based, you need a buffer array to connect between them.

To receive data from Firebase:

var buffer = [];

var admin = require("firebase-admin");
var db = admin.database();
var ref = db.ref("<path>");
ref.on("child_changed", function(snapshot) {
  var changedData = snapshot.val();
  buffer.push({
    x: Date.now(),
    y: changedData.value
  });
});

To update the dataset of the chart:

onRefresh: function(chart) {
  Array.prototype.push.apply(chart.data.datasets[0].data, buffer);
  buffer = [];
}

from chartjs-plugin-streaming.

Hi @nagix, I've tried your code but it doesn't work.
"Uncaught TypeError: buffer.append is not a function"

from chartjs-plugin-streaming.

Sorry, use buffer.push instead of buffer.append.

from chartjs-plugin-streaming.

v1.7.0 supports the push based data feed. You can rewrite the code above without onRefresh as follows:

var myChart = new Chart(ctx, config);

var admin = require("firebase-admin");
var db = admin.database();
var ref = db.ref("<path>");
ref.on("child_changed", function(snapshot) {
  var changedData = snapshot.val();
  myChart.data.datasets[0].data.push({
    x: Date.now(),
    y: changedData.value
  });
  myChart.update({
    preservation: true
  });
});

from chartjs-plugin-streaming.

Closing as answered.

from chartjs-plugin-streaming.