Auto populate text_fields based on selected item from another collection_select

Hello people

I'm trying to figured this out, but I still can't do it.

I have a rails 3 app, I'm working with invoices and payments. In the
form for payments I have a collection_select where I display all the
invoices number (extracted from a postgres database), and what I'm
trying to do is when i select an invoice autopopulate others
text_fields (provider, address, etc.) without reloading the page, in
the same form.

I know I should use ajax, js, jquery, but I'm a beginner in these
languages, so i don't know how or where to start

hope you can help me... thanks

I would do it as follows:

+ Set a jquery event on your select in some .js file:

$("#your_select_id").on("change", function(){
  $.ajax({
    url, data, etc... checj jquery docs
  });
});

I suggest .on() assuming you are using jquery 1.7. Alternatively you
can check .delegate() or .bind() if you are using older versions.

+ Controller:
def updating_action
  [...]
  respond_to do |format|
    format.js
  end
end

+ View updating_action.js:
Updating jquery and rails code such as

   $(id).val("<%=escape_javascript(@value)%>")

Check .val(), .replaceWith(), .text() and other similar jquery methods
to help you update your view.

Alternatively you can handle response on your ajax call, but I'm used
to do it like this, which seems to me easier and more flexible. Maybe
someone else can simplify it even more...

Anyway, hope it helps.