Articles

Quick hack to enable attributes

I came across the need to have a user list with checkboxes for ‘admin’ and ‘fleet_commander’ to allow them to be set. Which works great- until you realise that your user model is protected from forms setting those fields!

This was using the ‘Toggle Attributes with Ajax’ recipe from ‘Advanced Rails Recipes’- an excellent book, and one I’d recommend.

Essentially, I had a remote update function using AJAX, which sent a user params hash with the appropriate value set. However, to let the form update the model, I had to use some class_eval magic:

  def update
    if current_user.admin?
      User.class_eval('attr_accessible (usual stuff), :admin, :fleet_commander')
    end
    # continue onwards with updating using update_attributes
  end

This temporarily adds the :admin and :fleet_commander attributes to the list of accessible attributes by calling attr_accessible in the context of the User class. Hope this helps someone in the same scenario!

Posted by James Harrison on Aug 11, 2008

Where'd that month go?

OK, so it’s been a while since I posted a blog update. I’ve been busy- Band of Brothers declared war against the Northern Coalition so I’ve gotten swept up in the fighting and commanding. EVE Metrics has progressed well with constant work, and my holiday in Scotland was a success on all counts. And now it’s August. Blimey.

Anyway, back to Rails I go. I’ve been pondering the usual problems. REST is great for doing stuff on publicly accessible models- news posts and the like, for example. And scaffolds/make_resourceful can do that really, really well. But what about when you want to cater for private resources?

Posted by James Harrison on Aug 03, 2008

Processing market data - ActiveMQ, ActiveMessaging and Stomp

For EVE Metrics we ran into some scalability and other issues right away with the market. Uploading market history data was causing some major problems, so we had to break out the big guns in terms of distributed workers right away.

Basically, whenever our upload client throws a chunk of data (Say, 100 different orders for a type and the price history for the last month), we’re running at a minimum 128 SQL insert queries- this all adds up, even with bulk inserts. Then you have to factor in delta calculations for histories, which adds another two SQL queries for each history value- again, more queries, more time. As the complexity increased, we ended up with around 3 seconds to run all the queries for larger logfiles, which is no good in reality- the uploader can sometimes be trying to push 3 to 5 files at a time up to the cluster, and this hangs half the app servers immediately for 3 seconds or so.

So, we now avoid MySQL entirely, and use some enterprise-grade messaging to handle our distributed processing of logs, entirely asynchronously from the upload controllers and Mongrel. Details after the break.

Posted by James Harrison on Jul 04, 2008

Call for testers

This is a quick post (I’m going to be busy today and tomorrow) to throw out a request for testers for the EVE Metrics desktop application.

We’re looking for industrialists and people out in 0.0/lowsec PvPing to use the beta client to collect price data for the development of the EVE Metrics market system.

If you’re interested, please send me an email- the details are on the about page – and I’ll send you a link to get the beta copy of the software from.

Please note that the current program is Windows-only, although we hope to provide Linux and Mac OS applications in the near future. This updater uses both logfile and cache reading methods, so simply browsing the market is all you need to do (Although pressing ‘export log’ in the market a few times wouldn’t hurt), with the program running in the background. This is to test the scalability of the EVE Metrics website’s upload API and to confirm that we can handle the amounts of data we’re looking at. More on that in another post I’m about to write…

Posted by James Harrison on Jul 04, 2008

EVE Metrics - An update

I’ll be honest- I’ve not done much on EVE Metrics in the past few weeks. I’ve been fairly busy out in the real world (Hence the lack of blog posts), but I’ve also been dragged onto other projects in my spare time.

However, I’ve put them all aside, and intend to have the first part of EVE Metrics released by the end of the month. That section will be the market section and hopefully the basic industry features, though I’m still working out the details on those.

This isn’t a full-fledged huge post, but just a response to those who keep sending me EVEmails, IRC queries and emails to inquire. The site’s currently offline because of a bug in one of the API handlers which caused the application server to lock up and eat memory- I’ve got it fixed on my development server but don’t plan to deploy for another few weeks.

However, this post does serve one other purpose: If you’d like to see a feature as trader or industrialist, if you’d like to see a tool, or a particular feature, or maybe just a particular view of things, then send me an EVEmail or an email, or just grab me on IRC. It’s getting towards crunch time for feature decisions, so it’s now or never!

Posted by James Harrison on Jun 15, 2008