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Swirrl Blog Roundup

Posted by Ric Mon, 28 Jul 2008 10:47:00 GMT

Bill and I have posted some articles on SwirrlSpeak recently, which may also be of interest to readers of this blog.

We’ve discussed:

• why the semantic web is important (and why it has as yet failed to take off),
• why wikis can often be a better fit than bespoke software solutions,
• how Software as a Service can save the planet,
• why choosing good urls is so important,
• and how forecasting the income of startups can be akin to examining chicken entrails.

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Rails Envy, MVC and Burt Reynolds

Posted by Ric Wed, 23 Jul 2008 20:12:00 GMT

I was overjoyed this afternoon to find that my Proto.Menu article received a mention in episode 39 of Gregg and Jason’s fantastic Rails Envy podcast.

At first I was puzzled as to why they referred to me as “Ric Mon” (sounds like my Patois alter ego). But then I realised that I’d posted that article on a Monday, so the header reads: “Posted By Ric Mon”. :-)

Anyway, their mention reminded me that I’d been meaning to link to their hilarious MVC public service announcement videos. They’re worth a watch, if only for the Burt Reynolds sections (check them out and you’ll see what I mean).

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Proto.Menu for context menus on Rails

Posted by Ric Mon, 14 Jul 2008 08:02:00 GMT

Last month, I posted a couple of articles about how to use various javascript libraries in your rails app. This is the latest in the series: using Proto.Menu for context menus.

Proto.Menu is a very lightweight (~3 KB) javascript library which allows you to add context menu functionality into your page. Without further ado, here’s how to use it with Ruby on Rails…

1. Download Proto.Menu from here (I’m using v0.6). All this gives you is a small javascript file.

2. Copy this javascript file into your rails project (in public/javascripts).

3. Create a new helper, proto_menu_helper.rb, and add the following code into it:

module ProtoMenuHelper

  # add a proto menu to the page.
  # element_id : the id of the element to which to attach the menu
  # menu_items : an array of hashes containing the menu items.  Each hash can contain:
  #   name: the string to show on the menu
  #   className: the class name to give the item on the menu
  #   callback: a function to call when the item is clicked
  # class_name : The css class name to give to the menu (optional, with default).
  def add_proto_menu( element_id, menu_items, class_name = 'menu desktop' )

    menu_items_js = "[" 

    menu_item_iterator = 0
    menu_items.each do |menu_item|    
      menu_item_js = options_for_javascript menu_item
      menu_item_js += "," unless(menu_items.length == (menu_item_iterator +1))
      menu_items_js += menu_item_js
      menu_item_iterator += 1
    end

    menu_items_js += "]" 

    # Add the javascript to the content for proto menus javascript.  
    # This is yielded in the app layout.
    content_for :register_proto_menus_js do
      "
        new Proto.Menu({
          selector: '#{"#" + element_id}', 
          className: '#{class_name}',
          menuItems: #{menu_items_js},
          fade: true,
          beforeShow: function() { 
            /* hide all other menus */
            menus = $$('.menu'); 
            menus.each(function(element) {
              element.hide();
              });
            }
        });
      " 
    end

    return "" # the helper itself returns nothing.

  end
end

• I’ve added a beforeShow callback which hides all other Proto.Menus on the page when a Proto.Menu is shown. If you omit this, you will be able to have many context menus on the page at once… Proto.Menu by default allows one context menu to be shown per element.
• The add_proto_menu method takes an optional class_name. This is the css class that the context menu will be given – change the default to whatever you want. The author of Proto.Menu provides an example CSS file here.
• You might notice that this helper returns nothing. Each time the add_proto_menu function is called, we’re accumulating some javascript code. This will be yielded in the head of the html (all will become clear as you read on). The reason I’ve done this is because Internet Explorer seemed to have a problem with the javascript when it was ‘inline’ (i.e. in the html body, in script tags).

4. Add a method in your application helper as below. Change the stylesheet_link_tag to point to whatever stylesheet you want to use to style your context menus.

  def use_proto_menu
    @content_for_proto_menu_css = ""
    @content_for_proto_menu_js = ""
    content_for :proto_menu_css do
      stylesheet_link_tag "proto.menu"
    end
    content_for :proto_menu_js do
      javascript_include_tag "proto.menu"
    end
  end

5. In the application layout, yield the appropriate contents, and add a bit of javascript which calls the register_proto_menus_js javascript when the dom is loaded. Obviously, if you add elements with ajax after the DOM is loaded, this function will not be called – you’ll need to call it manually.

<head> 
  <!-- ... -->
  <%= yield :proto_menu_css %>
  <%= javascript_include_tag "prototype" %>
  <%= javascript_include_tag "scriptaculous" %> 
  <%= javascript_include_tag "effects" %> 
  <%= javascript_include_tag "controls" %>
  <%= yield :proto_menu_js %> 
  <!-- ... -->
  <%= javascript_tag("
       function registerContextMenus() {
          #{yield(:register_proto_menus_js)} 
       }

       document.observe('dom:loaded', registerContextMenus );
       "   +
       (yield(:page_scripts) ? yield(:page_scripts) : "")
      )
    %>
</head>

6. Finally, to use the Proto.Menus in your views do something like the following (you might want to wrap this code up into your own relevant helper in the interest of keeping your views nice and tidy).

<% use_proto_menu -%>
<% 
  menu_item1 = 
    {
      :name => "menu item 1'",
      :callback => "function() { 
        alert('menu item 1');
        }
        "
    }

  menu_item2 = 
    {
      :name => "menu item 2'",
      :callback => "function() { 
        alert('menu item 2');
        }
        "
    }

  menu_items = [menu_item1, menu_item2]
  add_proto_menu('my_element_id', menu_items)    
%>

See the Proto.Menu site for more information. You might also want to take a look inside the proto.menu.js file itself, as there are some options which aren’t documented on the site.

Happy context menu-ing!

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proxy: error reading status line from remote server

Posted by Ric Fri, 04 Jul 2008 10:15:00 GMT

A few months ago, on Swirrl’s test server, we were seeing errors like this in the Apache error log, about once a day (normally when the server had been idle for a while – i.e. overnight)

proxy: error reading status line from remote server ...

The (ruby on rails) application would be non-responsive, and the only way to get it going again would be to restart its mongrels.

After a bit of head-scratching and Googling, we realized that it was because we didn’t have the MySQL gem installed on that server. The MySQL gem installs a MySQL API module for Ruby. It provides the same functions for Ruby programs that the MySQL C API provides for C programs.

(We also made a small change to our Apache config, but I don’t think that this made any difference.)

One small gotcha is that some of the ActiveRecord error messages produced with/without the MySQL gem are different, so if you’re doing any custom error handling (e.g. for database uniqueness violations etc), you might want to check this.

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Macports and Ruby 1.8.7

Posted by Ric Tue, 01 Jul 2008 19:26:00 GMT

Last month, I wrote about how Macports now gives you Ruby 1.8.7 by default (with which Rails has problems), and that I didn’t know how to get back to 1.8.6.

If you’re having the same problem, this post by Robby Russell might help you out.

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