Philipp Schmid

I just bought the song.

Because the 1.1.3 firmware seems to take up more space on the system partition than 1.1.2, you quickly start running into disk space problems.

To solve these problems (like the Installer jumping to Springboard while installing a package) you can move your applications folder to the media partition, here is how:

Connect to your iPhone using SSH and issue the following commands.

cp -r /Applications /private/var/

chmod +s /Applications/Installer.app/Installer

Close your SSH session.

You should now be able to run all applications and install new ones.

By accident I just found out that if you type the ActiveRecord model name in your Rails console session (script/console), it prints out all the attributes of your model.

Now more trips to your database, to find out how attributes are named!

Delayed:netmonic schmidp$ script/console 
Loading development environment (Rails 1.99.0)
>> XenServer
=> XenServer(id: integer, hostname: string,
created_at: datetime, updated_at: datetime, slots: integer,
created_by: integer, updated_by: integer)
>> XenVm
=> XenVm(id: integer, customer_id: integer,
xen_server_id: integer, name: string, memory_size: integer,
swap_size: integer, disk_size: integer, architecture: string,
distribution: string, filesystem: string,
created_at: datetime, updated_at: datetime, internal_name: string,
state_id: integer, created_by: integer,
updated_by: integer)
>>

UPDATE:

I didn't know about the ARCHFLAGS environment variable, this is a less intrusive way (thanks to Sebastian for pointing this out):

sudo su -
ARCHFLAGS='-arch i386' gem install mysql -- --with-mysql-config=/usr/local/mysql/bin/mysql_config

(sudo su - asks you for your normal password not the root password)

I'm using the stock ruby environment on Leopard and the MySQL Package from http://www.mysql.com. Unfortunately installing the mysql driver as a gem doesn't work out of the box and the default mysql driver that comes with rails seems to be quite buggy.

cd /usr/lib/ruby/1.8/universal-darwin9.0/
sudo mv rbconfig.rb rbconfig.rb.orig
sudo sed "s/-arch ppc//g" rbconfig.rb.orig > rbconfig.rb
sudo gem install mysql -- --with-mysql-config=/usr/local/mysql/bin/mysql_config

(if you use a PPC Mac replace ppc with i386 on line 2)

Google just released their new offline-webapp Firefox and Internet Explorer plugin called Google Gears.

It's basically offers a persistent relational database that you can access from Javascript, as well as way to run Javascript code asynchronous, which is important if you have run expensive code.

We now have Firefox itself, Google, Adobe and Microsoft offering ways to take web applications offline. Google's offer is quite easy to integrate into your site and I guess as soon Google starts to use it in their own applications many people will have it installed in their browser.

As they have released it under the BSD license I wonder if they can get Mozilla to integrate it in their browsers, but it seems unlikely because Firefox 3.0 will feature a similar feature on it's own. But they could still distribute it with other applications Google offers.

Videos of the complete Steve Jobs and Bill Gates interview:

• Steve Jobs and Bill Gates Prologue
• Steve Jobs and Bill Gates Part 1
• Steve Jobs and Bill Gates Part 2
• Steve Jobs and Bill Gates Part 3
• Steve Jobs and Bill Gates Part 4
• Steve Jobs and Bill Gates Part 5
• Steve Jobs and Bill Gates Part 6
• Steve Jobs and Bill Gates Part 7
• Steve Jobs and Bill Gates Highlight Reel
• Steve Jobs and Bill Gates Session Transcript

"Businessweek profiles "Metro" -- a prototype laptop designed by Intel and Ziba Design. The 0.7 inch thick laptop is the world's thinnest notebook and weighs only 2.25 pounds."

"Other design-oriented features include different color choices, one side featuring an E Ink screen, and the addition of a shoulder strap (image)."

Source: Macrumors

I'm currently working on project involving a J2ME client on a mobile phone connecting to a Rails RESTful web service. As you might know, a RESTful web services utilizes the four HTTP verbs GET, POST, PUT and DELETE.

So yesterday we started to write unit tests, running on a J2ME device, which test if the Rails web service conforms to our specification, then suddenly we got this:

IOException: "unsupported method: PUT"

Huh?

We had the web service specification finished, the Rails Application was nearly finished, the J2ME web service adapter was finished, the J2ME GUI was underway - over 500 hours of work and suddenly this!

You can imagine our faces as we looked at the screen, reading the exception on the tiny display of the Nokia mobile phone emulator.

We went to the Sun site to get the sources of the J2ME MIDP2.0 reference implementation and found this:

public void setRequestMethod(String method) throws IOException {
    if (!method.equals(HEAD) && 
        !method.equals(GET) && 
        !method.equals(POST)) {
        throw new IOException("unsupported method: " + method);
    }
    this.method = method;
}

Why the hell did they do that? Why are they restricting the HTTP verbs to HEAD, GET and POST? Security? Fun?

To our luck, there is also another widely deployed platform/application that only supports GET and POST: the browser!

So when Rails started to support RESTful controllers and routing, they had to invent a mechanism to piggy-back PUT and DELETE requests on the POST method.

Rails solves this by using a hidden field in HTML forms named _method, but you can also specify _method as an URL parameter (given that you send a POST request):

http://localhost:3000/submarks/1?_method=put

Rails certainly intended this for the browser, but it also works with XML requests if you specify the method as URL parameter and can save your life if you use J2ME - at least it saved us from a serious headache.

Thank you Rails! And to you J2ME guys: please, remove those five idiotic lines - there are more verbs than those three.

The Rails application I'm currently working on accepts URLs like:

GET /submarks
GET /submarks?lat=:latitude&lng=:longitude
GET /submarks?lat=:latitude&lng=:longitude&user=:user_id
GET /submarks?lat=:latitude&lng=:longitude&channel=:channel_id
GET /submarks?lat=:latitude&lng=:longitude&channel=:channel_id&user=:user_id

All query parameters are optional, only lat and lng have to appear together. On the Rails end, I have a Submark model with the attributes: lat, lng, user_id and channel_id.

So how do you implement find call on the Submark model without a long, ugly if-elsif-else statements? First of all if you only have = as comparators you can use a Hash for the :conditions parameter of the find method:

conditions = {}
conditions[:user_id] => params[:user] if params[:user]
conditions[:channel_id] => params[:channel] if params[:channel]
Submark.find(:all, :conditions => conditions)

But what if you want OR instead of AND in the WHERE clause? Or what if you want do something like lat < 16? Currently, you have revert back to ugly if-elsif-else statements like:

if params[:user] and params[:channel].nil?
  Submark.find(:all, :conditions => ["user_id = ?", params[:user]])
elsif params[:user].nil? and params[:channel]
  Submark.find(:all, :conditions => ["user_id = ?", params[:user]])
elsif params[:user] and params[:channel]
  Submark.find(:all, :conditions => ["user_id = ? AND channel_id = ?", params[:user], params[:channel]])
else
  Submark.find(:all)
end

A good solution for this problem is the ez_where plugin by Ezra Zygmuntowicz and Fabien Franzen. It includes new find_where method in your ActiveRecord models which takes a code block building the conditions with a quite nifty syntax.

But I didn't want to depend on a external plugin, mainly because we are working with edge Rails, so it's not unlikely that ez_where breaks sometime during development.

Instead I've implemented a little helper, create_conditions, which is able to construct a conditions array, in the format the usualfind method likes. It also works by utilizing a code block. You get a Conditions class as parameter to your code block, which has the methods and and or.

This is how you would use create_conditions in your controller:

conditions = create_conditions do | c |
  c.and ["channel_id = ?", params[:channel]] if params[:channel]
  c.and ["user_id = ?", params[:user]] if params[:user]
  c.or "distance < 10"
end
Submark.find(:all, :conditions => conditions)

The result of create_conditions looks like:

["channel_id = ? AND user_id = ? OR distance < 10", 1, 42]

As you can see, you can use both, String or Array based conditions. Hash based conditions are not supported.

Get the code here.

Although I've been using Rails for some time now, I somehow missed out on DHH's speach during lasts RailsConf.

If you are working on CRUD or RESTful Rails applications (if you don't, you should), and haven't seen it yet, you are definitely missing out too!

The new NIN Year Zero album CD has a really cool a thermal secret. It changes from black to white as it heats up in the CD player and reveals some binary code.