Redraw Google Chart after every Ajax call

Question

When the chart loads the first time with the initial default Ajax reply, it works fine. If I add in console.log(chart_data), I see my default data, then after my submit I see the new data. The only problem is the chart doesn't draw itself again. I know the drawChart function is not ran a second time, I just don't know why. I'm assuming if it is, the chart will redraw itself. Sorry if the answer is obvious; I am very new to jQuery/Ajax.

var chart_data;
var startdate = "default";
var enddate = "default";

function load_page_data(){
    $.ajax({
        url: 'get_data.php',
        data: {'startdate':startdate,'enddate':enddate},
        async: false,
        success: function(data){
            if(data){
                chart_data = $.parseJSON(data);
                google.load("visualization", "1", {packages:["corechart"]});
                google.setOnLoadCallback(function(){ drawChart(chart_data, "My Chart", "Data") })
            }
        },
    });
}

load_page_data();

function drawChart(chart_data, chart1_main_title, chart1_vaxis_title) {
    var chart1_data = new google.visualization.DataTable(chart_data);
    var chart1_options = {
        title: chart1_main_title,
        vAxis: {title: chart1_vaxis_title,  titleTextStyle: {color: 'red'}}
    };

    var chart1_chart = new google.visualization.BarChart(document.getElementById('chart1_div'));
    chart1_chart.draw(chart1_data, chart1_options);
}

Any help would be appreciated. Thanks!

Answer 1

you should only be doing google.load once in a page. The fact that you're loading data complicates things a little bit, but not by much. I would recommend that you do the google.load once at the top of your javascript, and have load_page_data set as the callback. Then, you would call drawChart from there. The modified code would look something like the following:

var chart_data;
var startdate = "default";
var enddate = "default";
google.load("visualization", "1", {packages:["corechart"]});
google.setOnLoadCallback(load_page_data);

function load_page_data(){
    $.ajax({
        url: 'get_data.php',
        data: {'startdate':startdate,'enddate':enddate},
        async: false,
        success: function(data){
            if(data){
                chart_data = $.parseJSON(data);
                drawChart(chart_data, "My Chart", "Data");
            }
        },
    });
}

function drawChart(chart_data, chart1_main_title, chart1_vaxis_title) {
    var chart1_data = new google.visualization.DataTable(chart_data);
    var chart1_options = {
        title: chart1_main_title,
        vAxis: {title: chart1_vaxis_title,  titleTextStyle: {color: 'red'}}
    };

    var chart1_chart = new google.visualization.BarChart(document.getElementById('chart1_div'));
    chart1_chart.draw(chart1_data, chart1_options);
}

Answer 2

If you've already determined that the function isn't firing the second time by a console.log or something then you might want to try taking the params off your function and call it how Google does in their examples:

google.setOnLoadCallback(drawChart);

Your code looks fine to me but I'm not sure how setOnLoadCallback preps params as I'm not very familiar with the charts libraries.

https://developers.google.com/chart/interactive/docs/basic_load_libs