Error "Cannot read property 'DataTable' of undefined" in code working since years

RBTCGP

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Aug 6, 2020, 3:25:43 AM8/6/20

to Google Visualization API

<html>
  <head>
	<title>xxxxxxxxxxxxxxxxx</title>
	
	<link rel="stylesheet" type="text/css" href="./css/style.css" />
	<link rel="stylesheet" href="mystyle.css">
        <meta http-equiv="refresh" content="80; URL=http://xxxx">
	
  <!--Load the AJAX API-->
    <script type="text/javascript" src="https://www.google.com/jsapi"></script>
    <script type="text/javascript" src="//ajax.googleapis.com/ajax/libs/jquery/1.10.2/jquery.min.js"></script>
    
 <script type="text/javascript">

    // Load the Visualization API and the piechart package.
    google.load('visualization', '1', {'packages':['corechart']});
      
    // Set a callback to run when the Google Visualization API is loaded.
    google.setOnLoadCallback(drawChart);

	var ticksArray = [{v: 1, f: '26.11.15'}, {v: 2, f: '09.12.15'}, {v: 3, f: '22.12.15'}, {v: 4, f: '13.01.16'}, {v: 5, f: '27.01.16'}, {v: 6, f: '17.02.16'}, {v: 7, f: '02.03.16'}, {v: 8, f: '16.03.16'}, {v: 9, f: '14.04.16'}, {v: 10, f: '11.05.16'}, {v: 11, f: '04.08.16'}, {v: 12, f: '07.09.16'}, {v: 13, f: '08.12.16'}, {v: 14, f: '19.12.16'}, {v: 15, f: '22.12.16'}, {v: 16, f: '05.04.17'}, {v: 17, f: '11.05.17'}, {v: 18, f: '08.06.17'}, {v: 19, f: '13.07.17'}, {v: 20, f: '28.07.17'}, {v: 21, f: '26.07.18'}, {v: 22, f: '08.08.18'}, {v: 23, f: '29.08.18'}];

	var Eingabe = "";
	var Zaehler = 1;
	while (Zaehler <= 3) {

	Zaehler++;

	function drawChart() {
          var jsonData = $.ajax({
          url: "Antwortzeiten_XXX.php?",
          dataType:"json",
          async: false
          }).responseText;
       
      // Create our data table out of JSON data loaded from server.
      var data = new google.visualization.DataTable(jsonData);

      // Instantiate and draw our chart, passing in some options.
      var chart = new google.visualization.LineChart(document.getElementById('chart_div'));
      chart.draw(data, {width: 800, height: 240});
    }
	window.setTimeout(drawChart(), 10000);	
}	

    </script>
	
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
  
  </head>


<body>
       
    <!--Div that will hold the pie chart-->
	
	<div id="chart_start_div">
	
	<script>
	function drawChart() {
      var jsonData = $.ajax({
          url: "XXXXXXX.php?seite=Start",
          dataType:"json",
          async: false
          }).responseText;
       
      // Create our data table out of JSON data loaded from server.
      var data = new google.visualization.DataTable(jsonData);

      // Instantiate and draw our chart, passing in some options.
      var chart = new google.visualization.LineChart(document.getElementById('chart_start_div'));

      chart.draw(data, {explorer:{axis: 'horizontal'}, width: 800, height: 240, hAxis: {ticks: ticksArray}});
    }
	window.setTimeout(drawChart(), 10000);	
	</script>
	
	</div>
	
  </body>
</html>

The above code worked for years.

Now I get no graph anymore without any change by myself.

Maybe there was a change in Google graphs, which makes it necessary to change the code?

In the line "var data = new google.visualization.DataTable(jsonData);" I get the error "Uncaught TypeError: Cannot read property 'DataTable' of undefined".

The php works fine to provide the JSON-Data.

The goal is, that the graph updates itself automatically every 10 seconds.

RBTCGP

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Aug 6, 2020, 5:38:50 AM8/6/20

to Google Visualization API

Also the error remains, when I exchange

with the line

<script src="https://www.gstatic.com/charts/loader.js"></script>

Daniel LaLiberte

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Aug 6, 2020, 12:02:02 PM8/6/20

to Google Visualization API

The problem is due to your window.setTimeout(drawChart(), 10000); This actually calls drawChart immediately, since you wrote drawChart() rather than just drawChart. What it does after 10 seconds is try to call the undefined result of calling drawChart.

You should wait for google.setOnLoadCallback(drawChart); to call drawChart after the library has finished loading, at which time google.visualization.DataTable should be defined. Then, *within* your drawChart function, you could call drawChart again after a timeout.

But you have other problems. You have 2 drawChart functions, one in the head, which references chart_div, which doesn't appear to exist (this first script appears to have a syntax error, an extra '}' at the end, so maybe it is ignored), and one in the body, which references the chart_start_div which *contains* the script that defines drawChart. So assuming only the second drawChart is used, when the chart is drawn, the script element will be deleted. What that does to the drawChart function may be undefined, or it might still exist if it is attached to some other place in the document. In any event, this is probably not what you want to do.

Finally, you should follow the instructions at https://developers.google.com/chart/interactive/docs/basic_load_libs#update-library-loader-code

to update how you load the Google Charts library. Why the behavior of your page has changed might be due to the jsapi loader redirecting to the new loader. Difficult to say without seeing how this is working in your actual web page. If you can point us at that page, we might be able to help more.

I hope this helps, though I know I am not giving you a solution, but mostly just pointing out problems.

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Daniel LaLiberte

dlaliberte@Google.com Cambridge MA

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RBTCGP

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Sep 5, 2020, 6:31:37 AM9/5/20

to Google Visualization API

Dear Daniel,
thank you very much for your hints.

I think the main problem is the obsolete load of the google charts library, as I have the same problem with all my html, where I use it.

So I already tried to follow the instructions at https://developers.google.com/chart/interactive/docs/basic_load_libs#update-library-loader-code.

But with no effect. Maybe you can have a look at another example, which is the actual code and which is a little bit smaller (sorry, but I did not find a way to mark it as code this time):

<html>

<head>

<!-- OBSOLETE: <script type="text/javascript">

// Load the Visualization API and the piechart package.

google.load('visualization', '1', {'packages':['corechart']});

// Set a callback to run when the Google Visualization API is loaded.

google.setOnLoadCallback(drawChart);-->

google.charts.load('current', {packages: ['corechart']});

google.charts.setOnLoadCallback(drawChart);

var Eingabe = "";

var Zaehler = 1;

while (Zaehler <= 3) {

Zaehler++;

function drawChart() {

var jsonData = $.ajax({

url: "Antwortzeiten_Nbg.php?",

dataType:"json",

async: false

}).responseText;

// Create our data table out of JSON data loaded from server.

var data = new google.visualization.DataTable(jsonData);

// Instantiate and draw our chart, passing in some options.

var chart = new google.visualization.LineChart(document.getElementById('chart_div'));

chart.draw(data, {width: 400, height: 240});

}

window.setTimeout(drawChart(), 5000);

}

</script>

</head>

<body>

function drawChart() {

var jsonData = $.ajax({

url: "Antwortzeiten_Nbg.php",

dataType:"json",

async: false

}).responseText;

// Create our data table out of JSON data loaded from server.

var data = new google.visualization.DataTable(jsonData);

// Instantiate and draw our chart, passing in some options.

var chart = new google.visualization.LineChart(document.getElementById('chart_div'));

chart.draw(data, {width: 400, height: 240});

}

window.setTimeout(drawChart(), 5000);

</script>

</div>

</body>

</html>

Daniel LaLiberte

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Sep 5, 2020, 2:13:26 PM9/5/20

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I still see: window.setTimeout(drawChart(), 5000);

Which calls drawChart immediately, not after a timeout. I expect you want to wait until after the timeout, so you should instead do:

window.setTimeout(drawChart, 5000);

The value of the expression drawChart is a function, and setTimeout expects a function as its first argument (or a string, but don't use it that way). The function given to setTimeout is called by setTimeout after the amount of time you specify. So you don't want to call the function before the timeout occurs.

To view this discussion on the web visit https://groups.google.com/d/msgid/google-visualization-api/ea8134e0-9be0-4ff2-9885-96c82cd216f2n%40googlegroups.com.

RBTCGP

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Sep 9, 2020, 10:24:10 AM9/9/20

to Google Visualization API

Hello Daniel,

I changed this line in the head and in the body as you suggested. But I still do not get the graph as I got it with this old line.

RBTCGP

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Sep 19, 2020, 6:10:09 AM9/19/20

to Google Visualization API

Thanks a lot! Somehow after the Google source has been updated the window.setTimeout(drawChart(), 5000) really had to be changed to window.setTimeout(drawChart, 5000); I looked through the code again and now I get my graph updated again.

Additionally do you know, where in the code I have to add something to get a 2nd line in this graph for data also comming from a PHP script, which just gets the data from another DB-table?

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