Rails 3 In-Place Editing

Question

I'm trying to implement in-place editing in a Rails 3 app that takes the edited value and revises a calculation based on that value. For example:

Before edit of the "credits to donate" field:
You have 10 credits remaining. Credits to donate: 0.

After edit of the "credits to donate" field:
You have 5 credits remaining. Credits to donate: 5.

I have looked into various options, and it looks like the jquery-in-place-editor does what I'm looking for. For reference:

• jQuery-in-place-editor code
• Sample Rails app
• Github Repo of Sample Rails app

The demo works. But I think what I need to do is use the callback function to call a ruby script, so I can do some more processing. I'm not entirely sure if that's what I need to do though, so I'm looking for some guidance.

Here is the jQuery javascript (from /public/javascripts/application.js in the Sample app) that I think is relevant:

// Using a callback function to update 2 divs
$("#editme4").editInPlace({
    callback: function(original_element, html, original){
        $("#updateDiv1").html("The original html was: " + original);
        $("#updateDiv2").html("The updated text is: " + html);
        return(html);
    }
});

It looks like what I need to do is take original and html and play around with them a bit, then feed them back to the appropriate divs. The question is, how do I do this? I'm thinking of two possibilities:

A. There is a facility in the jquery-in-place-editor to call a url. Could I use this to call a ruby script and get a result? How would I do this in rails? Here is code to call a url (again from /public/javascripts/application.js); but it calls a php script.

$("#editme1").editInPlace({
    // callback: function(unused, enteredText) { return enteredText; },
    url: 'server.php',
    show_buttons: true
});

B. Modify the updated text directly in javascript, and pass it to the appropriate divs. I'd prefer to use a ruby script, but maybe this would be easier.

Answer 1

The solution to this problem is quite complex, but I have found a way to do it. It is surprising to me that the solution is not readily available, since it does seem, as r-dub says, something that is quite common. I ended up not using any of the edit-in-place facilities of a jQuery plugin, and instead modified a text field directly with the help of jQuery on the basis of a form text field. I other words, I followed (B) above.

I have a view that looks like this:

Available: <span id="available_cr"><%= @available_credits %></span>
Remaining: <span id="remaining_cr"><%= @remaining_credits %></span>

<%= form_for(@page, :html => { :id => 'do_fvalue' }, :remote => true) do |f| %>
  <div class="field">
    How many to buy at <%= @cost %> credits per unit? <%= f.text_field :fvalue, :autocomplete => :off %>
  </div>
  <div class="field">
    How many to buy at <%= @cost_20 %> credits per unit? <%= f.text_field :gvalue, :autocomplete => :off %>
  </div>
  <div class="actions">
    <%= f.submit "Update" %>
  </div>
<% end %>

I then stuff the rails @-variables into a .html.erb partial (rendered at the beginning of my page .html.erb) so that javascript/jQuery can access them:

<script type="text/javascript">
  var cost = parseInt(<%= @cost %>)
  var cost_20 = parseInt(<%= @cost_20 %>)
  var available_credits = parseInt(<%= @available_credits %>)
  var remaining_credits = parseInt(<%= @remaining_credits %>)
</script>

Then, in public/javascripts/applications.js, I have the following code:

function checkFields(){
  var to_buy_f = $("#page_fvalue").val();
  var to_buy_g = $("#page_gvalue").val();
  var subtract_f = to_buy_f * cost;
  var subtract_g = to_buy_g * cost_20;
  var remain = available_credits - subtract_f - subtract_g;
  $("#remaining_cr").text(remain);
};

$("#page_fvalue").keyup(function () {
   checkFields();
}).keyup();

$("#page_gvalue").keyup(function () {
   checkFields();
}).keyup();

The checkFields function updates #remaining_cr based on the values found in #page_fvalue and #page_gvalue. Notice that it makes use of available_credits, cost, and cost_20, which we stuffed into the javascript variables above. The last two functions tell jQuery to monitor #page_fvalue and #page_gvalue for keyup events. When the user presses a key, it calls checkFields() to update #remaining_cr.

All of this aside, when the user clicks "submit" on the form, the whole form gets submitted with the current values. I don't know whether this is the most efficient way to do what I was trying to do, but it works!

Answer 2

What you're trying to do is quite common. What you want to do is make an AJAX request within that callback sending the original data to your rails app and returning the modified html to your page. Here's the jQuery AJAX manual page. Scroll way down to see some examples.