Rails Validation Syntax

Tonight while working through Agile Web Development with Rails, I was finishing up Chapter 7 and doing some of the extra stuff at the end. One of the exercises was adding validation to the Product model that checks the length of product titles is at least 10 characters.

No big deal! I fired up Rails API and found what I was looking for.

validates_length_of :title, :minimum => 10, :message => 'must be at least 10 characters.'

Ahh, perfect! Plus, editing the default message is the second optional exercise. Easy enough. But wait, what's this?

The book had me write validation like so:

validates :price, :numericality => {:greater_than_or_equal_to => 0.01}, :message => 'must be a number.'

This is a slightly different syntax than the validation I found on the Rails API and I don't like it as much. First, it's not as immediately obvious what this validation is doing. Second, it just feels clunkier. So since I'd already written a validation method in a different syntax, I figured this would do the same thing and be in a more readable format:

validates_numericality_of :price, :greater_than_or_equal_to => 0.01, :message => 'must be a number.'

And what do you know? It works! Is there anything I should be aware of when writing validation like this? Any ideas why Agile Web Development with Rails wrote it the other way? Personal preference of the programmer, perhaps? I'm assuming this is a standard way of writing validation, both because it's the same syntax I found on the Rails API, and because it's more readable. (It's also 5 characters shorter, but who's counting? A piece of Javascript I found online, that's who!)

Ahh, feels good to be making progress. I got hung up for a bit writing tests in the last chapter, until I realized I'd added a stray period and it was holding everything up. Anyone else try running test:unites by mistake? I've probably done it 3 or 5 times in the last 18 hours.

More about Ruby, Databases and Syntax

So I was extremely lazy this weekend and only spent a couple hours working with Ruby. Awful! However, I think a little time away from actively learning caused a few things to click in my head. Imagine a pair of gears, left to their own devices after hours of meddling and tinkering, that suddenly come together and begin to move. Not smoothly, perhaps, but real motion!

It's hard to describe what clicked for me. The syntax seems to make more sense the more I work with it. While working through Beginning Ruby, I've been typing every bit of code out, then attempting to run it. It's good practice, both to get used to how Ruby is written as well as learning what will cause Ruby to throw up AND how to fix those little problems. How often do you guys do something stupid like this?

class Person
  attr_accessor :name, :age
end

fred = Preson.new
fred.name = "Fred"
fred.age = 35

puts fred.name
puts fred.age

Only to have Ruby throw up everywhere because of two little letters that got switched?

I'm guessing this transposition kind of crap is something that will haunt me FOREVER, but I'll get better at spotting it as I go along.

Also I would like to say that I wrote this bit of example code almost ENTIRELY from memory. So things are sticking. I still have a hard time believing how easy some of this is, but there's still plenty I don't really understand yet. Still, let's not get ahead of ourselves here.

Still working through Chapter 9. I just installed my_sql. How do you pronounce this, anyway? I heard a guy at the meetup a couple weeks ago call it "My Sequel" which seems better than "MY SQL" but I don't know.

Syntax Issues in Ruby

Still working through Chapter 3 of Beginning Ruby. It's slow going because every time I get to an example (and there are lots of examples) I have to stop and do it, then run it to see what it does. Then I try to change the code around using what I already know. Sometimes this works. I'm actually surprised at how often I can predict what will work in Ruby.

Sometimes it doesn't work. Take this bit of code for example. All it does is check a string for vowels and returns a result.

This code is valid:

x = "The quick brown fox jumped over the lazy dogs."
puts "This string has vowels" if x =~ /[aeiou]/

This code is not valid:

x = "The quick brown fox jumped over the lazy dogs."
if x =~ /[aeiou]/ puts "This string has vowels"

I don't get why this doesn't work. All I've done is rearranged the bits of code. It's possible I need a bit more code to make this work this way and it's possible it just doesn't work this way. It's also possible I'm just getting ahead of myself (again) but I've never been able to learn something, even the basics of something, without wanting to mess around with it and see what else it could do.

Either way, the example from the book didn't use a variable. In place of x the book had "Test string" which still returns the same result, "This string has vowels" but is less useful because a variable is more useful. If this was a bit of code I was actually going to use for something, I could pull that variable from anywhere - a file, user input, etc. So I don't have a problem understanding variables, at least.