using google chart api in rails app - how specify a null (missing) value in a series when using arrayToDataTable

Question

My app charts 4 data series using the google chart api. The controller loads an array, the view has the google chart javascript to draw the cart.

It works if the array

Answer 1

Answer turns out to be trivially simple...

a) on the ruby side, use nil

b) in the javascript, when passing in the array, instead of @typed_array, use @typed_array.to_json

In my controller, I load an array with data (fully populated array example):

@typed_array = [["Month", "Apples", "Bananas", "Cherries", "Oranges"], 
  ["Jan", 5.0, 4.0, 3.0, 7.0], 
  ["Feb", nil, 3, 3.0, 7.0], 
  ["Mar", nil, 5.0, 4.0, 6.0], 
  ["Apr", 8.0, nil, 4.0, 5.0], 
  ["May", 9.0, 6.0, nil, 4.0]]

The view contains:

%script{:src => "https://www.google.com/jsapi", :type => "text/javascript"}
:javascript
  google.load('visualization', '1.0', {'packages':['corechart']});

  google.setOnLoadCallback(drawChart);

  function drawChart() {

    // Create the data table.
    var data = new google.visualization.arrayToDataTable(#{@typed_array.to_json});

    // Set chart options
    var options = {'title':'Report 1: ',
         backgroundColor: { fill: "#fee", stroke: "#246", strokeWidth: 2 },
         'width':800,
                   'height':300,
                   'interpolateNulls':true};
    var chart = new google.visualization.LineChart(document.getElementById('chart_div_line1'));
    chart.draw(data, options);
  }

#chart_container
  %p  
  #chart_div_line1{:style=>"padding:20px;"}
  %p