Passing a parameter from button in the view to jQuery and use Ajax to pass that to a the controller method?

Question

I am fairly new to Rails and Haml. I am trying to have a button in my view that holds a "key" parameter which will pass that same parameter and trigger a method in the controller using jQuery with Ajax.

Everything can be done behind the scenes in my other class (it's a POST REST request) and I don't need to view anything other than a success message. I have debugged all the variables and the routes, however, the Ajax is not catching the key: parameter for some reason. It keeps saying undefined . I tried to hardcode the key parameter in the controller method and everything else is confirmed working but just missing the parameter.

In my view I have this line:

%button#start{ key: @start_key }= start

In my process.js file:

$(document).ready(function(){
    $('button#start').on('click', function(){
        var start_key = $('button#start').attr('key');   <------------
         $.ajax({
            url: '/process/start_process',
            data: start_key
         })
         $('#started_msg').text('started !!!');
     });
});

In my controller.rb, I have this method:

def start_process
    Client.start_process(params[:key])
End

I wasn't sure if this is the correct way to do this. Please feel free to give me some comments or whether there is additional information needed.

Answer 1

You're missing a few bits, see inline comments.

$(document).ready(function(){
    $('button#start').on('click', function(){
        var start_key = $('button#start').attr('key');
         $.ajax({
            url: '/process/start_process',
            method: 'POST', // <-- POST instead of GET
            data: { // <-- POST an object instead of just the value
                key: start_key // <-- named param
            }
         })
         $('#started_msg').text('started !!!');
     });
});

Before when you were just sending back the key "bare", the params array would have looked like this:

{"my-key-value"=>nil}

Now that you post an object back to the rails app, the params hash should contain the key "key", and the right value, eg:

{key: "my-key-value"}

If you look at your rails server request logs you should be able to see the differences. It lists the request parameters (at least rails 4 does and I think rails 3 did too).