Google Charts API rails plugin

09 Dec 2007

I bundled the code from the previous post into a plugin, called Chartr. This makes it easy to create graphs within rails.

Here's how to use it.

First, install the plugin. (It's probably a good idea to install it with '-x' since it's likely to be updated. Also, I should mention that this is my first plugin.)

    ruby script/plugin install -x svn://syvera.com/plugins/chartr

Right, so now we need to graph something. You can put a graph into any page, but let's create a page that definitely deserves a graph:

    ruby script/generate controller graphs index

This gives you an index.html.erb page where you can put your graph. In that page, we're going to use Chartr to give us a random graph. This is the code:

    <%= Chartr.make_simple_line_chart Array.new(5) {|i| rand(10)}, 
                                      ['one', 'two', 'three', 'four', 'five'],
                                      'stuff to graph' %> 

So that's going to give you a graph like this:

stuff to graph

Sure, that's cool. But what the heck were those arguments?

The first one is for your values:

    Array.new(5) {|i| rand(10)}  # returns an array of 5 random values between 0 and 9

The second, also an array, is for the legend. No explanation needed for that. The last is for the html 'alt' tag.

You could provide a fourth one for the size of the graph. If not, the default is 200x100.