Rails. How to Pass values from an array to the google chart script.

Question

Rails App. I have a Project and a Task Model. Tasks have a column project_id to set the project they belong to, and several completeness columns to indicate completeness of the task over the time (so I have a column 'completeness_at_3hours', 'completeness_at_6hours' etc), to indicate from 1 to 5 the level of completeness of the task.

I now need to graph, with google charts the completeness over the time of the tasks that belong to a project.

In my Projects controller I have

@tasks = Tasks.where("project_id = ?", params[:id])

So, now that I have the tasks of the selected project, in @tasks, how would I include the data in the google chart script?

function drawChart() {

        var data = google.visualization.arrayToDataTable([
          ['Time', '<%= @task.name %>', '????????'],
          ['<%= @task.created_at %>',  <%= @task.zerohours %>, '?????????'],
          ['<%= @task.created_at + 3.hours %>',  <%= @task.threehours %>, '????????'],
          ['<%= @task.created_at + 6.hours %>',  <%= @task.sixhours %>, '????????'],
          ['<%= @task.created_at + 9.hours %>',  <%= @task.ninehours %>, '????????'],
          ['<%= @task.created_at + 12.hours %>',  <%= @task.twelvehours %>, '????????']
        ]);

this works for only one task (the one that has just been created), but how do I pass to the script all the data contained in @tasks?

I mean, to retrieve the data in a simple table I would use:

<% @tasks.each do |task| %>
<%= @task.threehours %>
<%= @task.sixhours %>
<%= @task.ninehours %>
<%= @task.twelvehours %>
<% end %>

But how do I do the same thing but inside the google chart script?

Thanks a lot!!

Answer 1

As far as I can tell you want to pass additional tasks in place of question marks, right? If so, I have a solution. First you might want to wrap code in a function:

var data = google.visualization.arrayToDataTable(<%= make_a_chart %>);

and place it somewhere in a corresponding helper:

def make_a_chart
  result = []
  result.push make_labels, 
              make_data( 0, "zerohour" ), 
              make_data( 3, "threehours" ),
              make_data( 6, "sixhours" ),
              make_data( 9, "ninehours" ),
              make_data( 12, "twelvehours" )
  return result
end

def make_labels
  y = ["Time"]
  for task in Task.all do
    y.append task.name
  end
  return y
end

def make_data( time, completeness )
  y = Task.first.created_at + time
  for task in Task.all do
    y.append task[completeness]
  end
  return y
end

This code assumes that all tasks are started simultaneously and that your database is called "Task". Also it's most likely quite crude and can use some improvements.