JSON + Ajax + Ruby on Rails

While I would love to be using E4X, it isn't viable yet. So JSON it is. Here is how I got a simple JSON example working with Ruby on Rails over Ajax^[1].

I'll assume you have a Rails project up and running with at least one model, controller, views etc.

First you want to install the JSON gem; gem install ruby-json

Then go into your model's code and put in the following require; require 'json/objects'. While still in the model add a to_json method with the following code:

result = Hash.new
self.class.content_columns.each do |column|
    result[column.name.to_sym] = self.send(column.name)
end

result.to_json

Now off to the controller file you go. For this daft example I create the following method:

def jsonbit
    @link = Link.find(params[:id])
    @headers["Content-Type"] = "text/plain; charset=utf-8" 
    render_text @link.to_json
end

Then in your view you want to use prototype to fire off an Ajax call e.g. <%= remote_function(:complete => "var x = eval('(' + request.responseText + ')'); alert(x.title);", :url => { :action => :jsonbit, :id => link.id }) %>

So in that what we do is fire off a call to the jsonbit method with a model id and it returns JSON which is evaluated by JavaScript and one of the properties is alerted out.

Naturally you can return a collection of data and then loop through it using JavaScript too.

[1] Technically it should be Ajaj (Asynchronous JavaScript and JSON.) But really, nobody cares. So Ajax it is.