Blizzo :: The Morgan Blog » Technobabble

Rails gotcha using after_initialize hook and exists?

F. Morgan Whitney — Mon, 29 Nov 2010 18:49:10 +0000

While upgrading Ruby on Rails from 2.1 to 2.3, one of my models threw an ActiveRecord::MissingAttributeError exception when something used exists? to see if it was there. The issue turned out to be our after_initialize hook on the model. In our hook, we rely on looking up the value of one of the object attributes. This fails now because exists? only selects the primary key from the table, leaving the rest of the attributes undefined. Here is how we solved it:

def after_initialize
do_something if foo_attribute
rescue ActiveRecord::MissingAttributeError
reload
retry
end

This will cause all the attributes to be fleshed out the second time around.

Easy way to encrypt and decrypt files in OS X from command line

F. Morgan Whitney — Thu, 11 Nov 2010 18:44:43 +0000

I wanted an easy way to encrypt and decrypt files in OS X from the command line, so I added the following to my .profile file in my home directory:

enc() {
openssl des3 -salt -in $1 -out $1_enc
rm $1
}
dec() {
openssl des3 -d -salt -in $1_enc -out $1
rm $1_enc
}

Now I can quickly encrypt a file using ‘enc’:

$ cat secret.txt
this is a secret!
$ enc secret.txt
enter des-ede3-cbc encryption password: [password]
Verifying - enter des-ede3-cbc encryption password: [password]
$ cat secret.txt_enc
Salted__?

And decrypt it just as easily with ‘dec’:

$ dec secret.txt
enter des-ede3-cbc decryption password: [password]
$ cat secret.txt
this is a secret!

A couple of things to note. The encrypted file is saved using a _enc suffix, but when decrypting, it assumes you type the original filename, not the _enc version. I don’t mind this, but it could be altered to be a little smarter in this regard. Also, when encrypting it deletes the original file for you, and when decrypting it deletes the encrypted version. I prefer this automatic ‘cleanup’.

Using and testing the 303 response code in Ruby on Rails

F. Morgan Whitney — Fri, 15 Oct 2010 16:27:36 +0000

While building a Rest API call for our product, we needed the server to respond to a post with a “303 see other” response. Unfortunately, in Rails when you do a redirect_to, it always uses the 302 response code, even when you set the status explicitly:

redirect_to chunky_bacon_url(@bacon), :status => :see other
redirect_to chunky_bacon_url(@bacon), :status => :303

These don’t fail, but they dont do what you would expect. In my test I asserted that the response code was 303, and the test failed. After some digging I found that I could use the ‘head’ method to force rails to respond correctly:

head :see_other, :location=>chunky_bacon_url(@bacon)

My response assertion passed. Yay. But it was short lived, because this assertion failed after I made the change:

assert_redirected_to chunky_bacon_url(@bacon)

with an error deep inside response_assertions.rb. Inside the ‘assert_redirected_to’ method, the following line failed because @response.redirected_to returns nil, and then explodes when it tries to call dup.

original = { :expected => options, :actual => @response.redirected_to.is_a?(Symbol) ? @response.redirected_to : @response.redirected_to.dup }

I did some digging, and it turns out that when I used ‘head’ instead of ‘redirect_to’, the @response.redirected_to was never set. I fixed the test by asserting string equality directly in the response headers:

assert_equal chunky_bacon_url(@bacon), @response.headers["Location"]

OS X Tip, recover windows from external monitor

F. Morgan Whitney — Tue, 13 Oct 2009 02:27:20 +0000

So one latest OS X annoyance that I actually stumbled across the solution for. At work I hook up an external monitor to my MacBook Pro, and usually keep all my terminal windows on that one. When I leave, I try to remember to unplug the monitor before I close the lid, because last time I forgot to do that, I had to kill the applications over there and relaunch them to get access to them again.

I tried using expose, but that didn’t show the windows on the now disconnected monitor. I checked out the spaces dialogue as well, but that also didn’t work. I also went into the system preferences to the ‘displays’ screen, hoping to find the ‘gather windows’ button, but it was not present. I think you only get that button when an external display is connected.

The way I actually solved it was through app switching keyboard shortcuts. I used Cmd+Tab to switch to the inaccessible application, then used Cmd+~ to cycle through the windows. As each window received focus, a sliver of it appeared on the edge of my screen and I was able to drag it over.

Poor, poor snow leopard

F. Morgan Whitney — Wed, 26 Aug 2009 14:57:30 +0000

So Apple has released their new OS, Snow Leopard, and this is what the Apple homepage looks like:

Poor, poor Snow Leopard...

I imagine this leopard, chillin, enjoying a nice snowy day, when along comes an Apple photo crew.

*FWAP*, they nail him in the head with a snowball, and as he looks at them with annoyance, they snap his picture.

I can only hope that shortly after this picture was taken, the Leopard ate every single one of them.

Rails Gotcha Regarding Test Fixtures

F. Morgan Whitney — Fri, 06 Mar 2009 18:05:14 +0000

I wasted a chunk of time running in circles over this issue. I had assumed that when I loaded the fixtures into my database via ‘rake db:fixtures:load’ or ‘rake spec:db:fixtures:load’ in Ruby on Rails that it was blowing away all the data in all of my tables before creating records. It turns out that it only blows away data in tables for which you have fixtures, leaving any generated cruft in other tables behind.

Facebook Now Allowing Spam?

F. Morgan Whitney — Mon, 09 Feb 2009 15:44:40 +0000

You can’t turn around lately without hearing about the latest craze on facebook: 25 Random Things. The premise is, you put up 25 random and usually useless things about yourself, and then “tag” a bunch of people so that they can come read it and praise you for the witty and interesting things you have to say.

I am a bit p[icky when it comes to what shows up in my email box, so when a Facebook application sends me a message without my explicit approval, I report it for sending spam and then block it. The problem is, this isn’t an application. It’s a note, or something, and you can arbitrarily tag people.

The first time this happened it was my sister, and I scoured her 25 Random Things looking for where she mentioned me, even indirectly. There was no mention of me. Until now, “tagging” me usually meant I was in a photo, and I was happy to receive notification of a 3rd party putting information about me on the internet. Thats a good use of notification.

I went to my Facebook privacy settings and found that there was a setting to disable email notification when someone tags you in a note. That would be fine… until someone wrote something about me in a note and tagged me, and then I would have no idea.

So, users are violating the spirit of what tagging is supposed to be used for, which is hardly Facebook’s fault. But it still annoys me.I suppose I will not have to live with two flavors of chain letter style spam, one from traditional email, and one from facebook. Facebook should step up and find a way to solve this problem though, without forcing me to blanket deny all communications from them.

New Look for OLEX

F. Morgan Whitney — Wed, 17 Dec 2008 20:20:26 +0000

Today we deployed the latest version of our product OpenLogic Exchange (OLEX) and it includes a brand new look and feel. The design was truly done by concensus with our entire engineering department, and it came out better than anything I think I could have done in isolation.

I used a varierty of techniques I had not had the opportunity to play with before, like CSS sprites for repeating backgrounds, a CSS Reset stylesheet to get a better baseline for CSS behavior, and a more aggressive attempt at modularized widgets to simplify page construction.

Overall I am pleased with the results, but there are a few things that were difficult to overcome. We have a large pool of users still using IE6, so I had to use a patch to get alpha transparency support for PNGs. We are using a less traditional font for the site, which renders very differently in Linux, so I had to do a Linux specific stylesheet to make the site usable, and it still has a few issues. Future releases will tighten things up a bit, but it feels like a big step forward for now.

I’m going to be an Android

F. Morgan Whitney — Wed, 24 Sep 2008 00:50:58 +0000

After several hours of mashing the refresh button in Firefox, I was finally able to get to the G1 preorder form and place mine. On October 22nd, I will be the proud owner of a G1, the first Android powered smart phone. The phone has a touchscreen interface similar to the iPhone, but it also has a full qwerty keyboard that slides out. Not only that, but it is running Android, which is a very open development platform, which means all sorts of cool things will be developed for it.

Here are some links if you want to learn more:

Review: “I’m a PC” Commercial by Microsoft

F. Morgan Whitney — Mon, 22 Sep 2008 19:59:25 +0000

I saw this new Microsoft commercial the other day, and I have to say I think it’s brilliant for the following reasons:

It shines light on the fact that Apple is casting an unfair stereotype of PC users
It gives existing Microsoft costumers a group of people they can feel proud identifying with
It makes Apple look like elitist snobs (which, to be fair, they are)

Disclosure:

I am operating system agnostic. I use Linux at work, PC at home, have worked extensively with Mac’s. I consider them all fairly similar platforms for software development, with PCs lagging behind a little because of the lack of a real shell environment, but it still doesn’t slow me down all that much. I have an iPod, it was free. I don’t like it all that much more than the MP3 player it replaced, but it’s fine.

Conclusion:

Anyway, good job Microsoft (I don’t say that often). Also, Vista is a steaming pile of crap, and when I got my new PC with it preinstalled, all of my applications crashed so often I had to go revert to XP and download tons of hard to find drivers to get it all to work. Maybe they should hire the person who came up with that commercial to sort out their product development.