Now the RailsConf aftermath has calmed down, I wanted to let you know a little about a tool we announced at the conference that I’ve been working on for a while. We’ve bundled up an Engine Yard gentoo slice from our clusters and put it into a VMWare image.
All the information you’ll need is on that page and there’s more to come.
So the end of the conference has come, and I’m absolutely exhausted. In their wisdom O’Reilly only filmed the keynote this year, so I’ve uploaded my slides with some added notes (so you can get a better idea of what I said) if you missed the talk or were one of the 30+ that got kicked out due to the room being full. I’ll put more up later.
Here’s the presentation:
Oh, and if you liked my talk, feel free to recommend me on Working With Rails:
So, my talk proposal “Hosting and the Woes” just got accepted, in a nutshell it’s all about hosting Rails and the problems you come across. It will also have a questions and answers section at the end which will be hosted by a few Engine Yard members (Ezra Zygmuntowicz, Tom Mornini, Taylor Weibley, Corey Donohoe if he wants, and more).
Keep your eye out for updates, I’ll let you know confirmed attendee’s at a later date.
In case any of you are going to the Irish Web Technology Conference in Dublin which starts today and lasts until the end of the week, I’ll see you there! I’m doing a Ruby on Rails intro talk tomorrow (Wed 27th Feb) at 15:15.
Also note, it could be awful, I’m trying a new presentation style…lots of short, extremely large words, I believe it’s called the “Takahashi Method”. Here’s to falling flat on your face!
<update>
The new presentation method worked well, although I didn’t follow the pattern strictly, my slides are available in various formats here:
Most of you will know by now, that ActiveRecord isn’t the fastest ORM on the planet, so why use it for storing session data in your database? Plan A would be to flip over to SqlSession, which bypasses the ActiveRecord method and goes straight to the database. That’s fine for most sites, but what about those really high traffic sites?
Alexey Kovyrin (for scribd.com) has written the ultimate solution, FastSessions. FastSessions uses some clever MySQL (no, it’s not agnostic) tricks to make for real speedy session storing and lookup. Now I’m no database guru, but this plugin is by one of the MySQL Performance Blog fella’s so you can be sure that it does exactly what it says on the tin.
Installation and use is easy as pie:
piston import http://rails-fast-sessions.googlecode.com/svn/trunk/ vendor/plugins/fast_sessions
Rails environment configuration:
config.action_controller.session_store = :active_record_store
Set up your migration to create the table:
./script/generate fast_session_migration AddFastSessions
Run the migration:
rake db:migrate
Little tricks like not saving the session data back to the database unless it changes, or is not empty, make for a huge saving over time.
Read more about it here: http://code.google.com/p/rails-fast-sessions/.
I’ve noticed a lot of people asking questions about ajax, rjs, scriptaculous and other whizzy cool effects lately. So I thought I’d document a couple here so there’s less confusion about some of the simpler effects. I’ve included an element toggle on a hyper link, a simple div that updates with data from an action using linktoremote, and others. Enjoy.
This article is re-posted, from my old blog which will be removed in time.
You’ll learn effects like these: Video of ajax effects. Let’s continue…in the style of Gordon Ramsey:
All of these examples assume you have included the default javascript files in your application.rhtml file:
<head> <%= javascript_include_tag :defaults %> </head>
The first of our simple effects is going to have to be the simple toggle (hide/show) of a div element. There is no remote call used in this, it simply uses javascript (generated by our ruby code) to show and hide a element of our choice.
<%= link_to_function "toggle with my div", "Element.toggle('to_toggle')" %>
<div id="to_toggle">
Now you see me, now you don't!
</div>Next we’re going to fire an action from a linktoremote and then update a list of items on the page, this involves multiple code pieces in different files, keep up.
<!-- app/views/words/index.rhtml -->
<ul id="sentence">
<li id="word_1">baby</li>
<li id="word_2">unzip</li>
<li id="word_3">my</li>
</ul>
<%= link_to_remote "WHAT?!?", :url => { :controller => 'words',
:action => 'update' },
:loading => "Element.show('loading')" %>
<div id="loading" style="display:none;">Loading...</div>
<!-- app/controllers/words_controller -->
def update
@word = "laptop bag!"
return if request.xhr?
end<!-- app/views/words/update.rjs --> # hide the loading text page.hide 'loading' # insert a new li into the element with an id of sentence page.insert_html :bottom, 'sentence', "<li id='word_4'>#{@word}</li>"
Notice how we use the same name for our rjs file as we did for the action we called, and then we ask the controller to return if the request was an xml http request (which is what ajax uses). This way if we want to do both rjs and standard requests with the update action we can.
I also demonstrated the use of a loading div here, but you could use a loading image as well, like a spinny circular thing or dots…or whatever takes your fancy.
Let’s modify the above example to highlight the new element when it arrives, this one’s far too easy. Add this to the bottom of update.rjs:
page.visual_effect :highlight, 'word_4', :duration => 3
Now when the element is added, you’ll have your attention drawn to it. The duration can be left off because it’s optional and defaults to 2 seconds, I just wanted to make you aware that it’s there.
Again, modify our existing call and make it slide down instead of just appear, change the update.rjs to this:
# hide the loading text page.hide 'loading' # insert a new li into the element with an id of sentence page.insert_html :bottom, 'sentence', "<li id='word_4' style='display:none;'>#{@word}</li>" page.visual_effect :blind_down, 'word_4', :duration => 2
We added to our li item a style of display, and set it to none. This is standard inline css markup, so when the item is added to our page it’s hidden. Then we use the blind_down visual effect to slide it down with a duration of 2 seconds.
I hope this helps all the ajax beginners get started with effects you can play with, be sure to check out the Rails api documentation for more scriptaculous effects.
Any questions boys and girls?
Just in case any of you wonder why when you use REXML’s write method on ruby 1.8.6 (2007-09-24 patchlevel 111) [universal-darwin9.0] and possibly other versions, you get errors, it’s a bug in Apple’s REXML library. See this:
def write(writer=$stdout, indent=-1, transitive=false, ie_hack=false) Kernel.warn("#{self.class.name}.write is deprecated. See REXML::Formatters") formatter = if indent > -1 if transitive REXML::Formatters::Transitive.new( indent, ie_hack ) else REXML::Formatters::Pretty.new( indent, ie_hack ) end else REXML::Formatters::Default.new( ie_hack ) end formatter.write( self, output ) end
As you can see, the method sets a local variable of ‘writer’ in the method arguments, however at the bottom it uses ‘output’. A simple change of the bottom line fixes it:
formatter.write( self, writer )
For those who requested it, here’s how to use the formatter:
# I want to create a REXML document to output require "rexml/document" # Make a pretty formatter formatter = REXML::Formatters::Pretty.new( 2 ) # Create some silly xml example xml = REXML::Document.new '<moo>RAR!</moo>' # Write to STDOUT formatter.write( xml, $stdout ) # Write to file xml_file = File.open( "some_file.xml", "a+" ) formatter.write( xml, xml_file )
Recent Comments