draw google charts with JSON

How can I retrieve and use a dataset for google charts if it was a separate JSON file?? I tried jQuery getJSON but couldn't get it worked.. Google Viz should use the JSON to draw a bar chart Is there a native google API way? or can I find a way using jQuery and how? Thanks

      // Load the Visualization API and the piechart package.
  google.load('visualization', '1.0', {'packages':['corechart']});

  // Set a callback to run when the Google Visualization API is loaded.
  google.setOnLoadCallback(drawChart);

  // Callback that creates and populates a data table, 
  // instantiates the pie chart, passes in the data and
  // draws it.
  function drawChart() {

      // Create the data table.
      var data = new google.visualization.DataTabl开发者_如何学编程e();
      data.addColumn('string', 'Products');
      data.addColumn('number', 'Automated');
      data.addRows([
        ['Product 1', 85],
        ['Product 2', 75],
        ['Product 3', 90], 
        ['Product 4', 40],
        ['Product 5', 40]
      ]);

      // Set chart options
      var pie_options = {'title':'How Much Automated our Products are?',
                     'width':520,'height':300
                    };
      var bar_options ={'width': 620, 'height': 300, 
                        'title': 'Products',
                        'hAxis': {'title': '% Automated', 'titleTextStyle': {'color': 'red', 'fontSize': 16}}
                      }
      // Instantiate and draw our chart, passing in some options.
      var chart = new google.visualization.PieChart(document.getElementById('piechart_div'));
      chart.draw(data, pie_options);

     var chart = new google.visualization.ColumnChart(document.getElementById('barchart_div'));
     chart.draw(data, bar_options);
}

new google.visualization.DataTable(json) works.

Look the output of dataTable.toJSON() for the correct structure to use.

So, if you have a getjson.php script on your server that returns correctly formatted json, you could do that:

$.getJSON('/getjson.php', function(json) {
    var dataTable = new google.visualization.DataTable(json);
});