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Ajax Refresh

Viewing 2 posts - 1 through 2 (of 2 total)
  • June 17, 2019 at 10:25 pm #25544

    danwel

    Hello,

    I am using your line graph to graph data from a database. As more data is added to the database, I want to that data on the graph. To do this, I need to run the query on the database again. I want to use:

    <script src="http://code.jquery.com/jquery-2.1.3.min.js"></script>

<div id="responds1"></div>

<script>
 $(document).ready(function() {
   var refreshId = setInterval(function() {
      $("#responds1").load("dynamicgraph.php");
   }, 1000);
   $.ajaxSetup({ cache: true });
});
</script>

    This will be on my page where the graphs are displayed. The graphs themselves are in a different file, and by using this Ajax method, I can refresh the graphs without ending the session.

    Here’s my problem: when I run the program, the graphs will not show up, just my search bar. If I don’t use that code they show up fine.

    How can I make the graphs show up? Is there an easier way to get the php up update and send the new data points to the graph?

    Here’s my code:

    <html>
<head>
<script>
window.onload = function() {
var dataPoints = <?php echo json_encode($dataPoints, JSON_NUMERIC_CHECK); ?>;
var chart = new CanvasJS.Chart("chartContainer", {
	theme: "light2",
	title: {
		text: "Live Internet Speed"
	},
	axisX:{
		title: "Time in millisecond"
	},
	axisY:{
		includeZero: false,
		suffix: " Mbps"
	},
	data: [{
		type: "line",
		yValueFormatString: "#,##0.0#",
		toolTipContent: "{y} Mbps",
		dataPoints: dataPoints
	}]
});
setInterval(function(){

var xValue = dataPoints.length;
var yValue = dataPoints[dataPoints.length - 2].y;
 
dataPoints.push({ x: xValue, y: yValue });
xValue++;
chart.render();
},1000);
}
</script>
</head>
<body>
<div id="chartContainer" style="height: 370px; width: 100%;"></div>
<script src="https://canvasjs.com/assets/script/canvasjs.min.js"></script>
</body>

</div>

</html>
    June 18, 2019 at 9:49 pm #25556

    Shashi Ranjan

    @danwel,

    As we do not have a working sample project that we can run locally to understand the issue better, we can suggest a few modifications you can make to your files for creating a dynamic chart in PHP using data from MySQL database. We will first start with php service dynamicgraph.php which will provide data from the database. Please take a look at below code snippet for dynamicgraph.php service:

    $username = "root";
$password = "";
$dbname = "test";

// Create connection
$conn = new mysqli('',$username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
} 

$sql = "SELECT Label, y_value FROM chart_table";
$result = $conn->query($sql);

if ($result->num_rows > 0) {
    // output data of each row
	$obj = array();
    while($row = $result->fetch_assoc()) {
		$element = array($row["Label"],$row["y_value"]);
       	array_push($obj,$element);
	}
	echo json_encode($obj);
} else {
    echo "0 results";
}
$conn->close();

    You can call dynamicgraph.php service at certain interval using AJAX call and render the chart with data received from the service. Please take a look the below code snippet for the same:

    window.onload = function () {
	var chart = new CanvasJS.Chart("chartContainer",{
		title:{
			text:"Rendering Chart from database"
		},
		data: [{
			type: "line",
			dataPoints : [],
		}
		]
	});
		
	$.getJSON("dynamicgraph.php", function(data) {  
		$.each((data), function(key, value){
			chart.options.data[0].dataPoints.push({label: value[0], y: parseInt(value[1])});		
		});
		chart.render();
		updateChart();
	});

	function updateChart() {
		$.getJSON("dynamicgraph.php", function(data) {		
			chart.options.data[0].dataPoints = [];
			$.each((data), function(key, value){
				chart.options.data[0].dataPoints.push({label: value[0], y: parseInt(value[1])});		
			});
			
			chart.render();
		});
	}
	
	setInterval(function(){updateChart()}, 1000);
}

    Please check this sample project for a working example with sample code for creating dynamic charts using data from MySQL database in PHP.

    Also, please refer to this documentation page for step to step tutorial to create a Live Updating Charts from JSON API & AJAX.
    Live chart with dataPoints from external JSON

    —
    Shashi Ranjan
    Team CanvasJS

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