Working on Wednesday #4 : Rails for Zombies

(I finally managed to update Ubuntu to the 10.10 version, configure Unity to make it more usable, and I'm not ready to start the RoR tutorial I wanted to start last week.)

I used vim this week (instead of nano) for very simple file editing. I will force myself to use only vim on wednesday to really learn it. I plan to completly drop Komodo Edit once I'll be familar enough with vim to gain more time than I lose.

Rails for Zombies

Anyway. I finally get to start the Rails for Zombies tutorial. And here is what I learned.

There are two distinct things I'm going to learn here : Ruby and Rails. I discovered that I was already familiar with a lot of basic concepts of Rails, thanks to cakePHP. Model and table convention, model relationships (belongs to, has many, etc) were exactly the same.

Ruby on the other hand was new. But also very interesting. No need to add () after a method to call it when no args are passed, possibility to chain method of the same object (much like jQuery) and the use of dynamic (yet strongly typed) vars.

The first part of the tutorial (basic CRUD) was easy. I didn't find how to make a complex SQL query like this (cake) one :

$Zombie->find('all', array(
'order' => array('Zombie.graveyard' => 'ASC', 'Zombie.name' => 'DESC'
));

I guess it's just a matter of time before I learn how to to do in Rails anyway. I saw that there was more "advanced" method (much like the cake find method) that would surely allow such finding.

Part 2 : Validation and Relationships

The second part of the tutorial was more about models. Validation rules were pretty much the same as those of cakePHP. But the Ruby syntax makes it more concise.

I couldn't find how to retrieve the validation errors when saving an object using the create method (no problem when manually calling save, though).

I enjoyed being able to create binded instances by simply adding the binded element to the model. Not very clear isn't it ? Here some code to explain it better. The last two lines have exactly the same effect :

class Zombie < ActiveRecord::Base
end
class Weapon < ActiveRecord::Base
belongs_to :zombie
end
Weapon.create(:name => "Rocket Launcher", :zombie_id => 2)
Weapon.create(:name => "Rocket Launcher", :zombie => Zombie.find(2))

Later on, I had to select all weapons binded to a specific Zombie. I was able to find the a specific zombie using any of the two following commands :

z = Zombie.where(:name => "Ash").first
z = Zombie.find(:first, :conditions => { :name => "Ash" })

Then, I wanted to find the weapons binded to this zombie. First I tried the following command :

Weapon.where(:zombie_id => z.id)

Obviously, this worked. But I wanted to test some more of the Rails magic. So I tried something along the lines of what I did in the previous chapter and tried to use my z var directly instead of z.id.

Weapon.where(:zombie => z)

This didn't worked. Well, I guess I'll also learn why later on. But one even more weird thing is that the following command did work even I'm not really sur why ?

Weapon.where(:zombie_id => z)

That's all I did today (well I also did some more Mercurial and Dingux testing, but that wasn't really work)


Tags : #wednesday #ruby-on-rails #ror

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