Rails tricks

gistfile1.txt

One that seems to surprise a lot of people is Hash.from_xml:

 > hash = {:foo => 'bar', :baz => 'qux'}
 => {:foo=>"bar", :baz=>"qux"}
 > hash.to_xml
 => "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<hash>\n
<foo>bar</foo>\n  <baz>qux</baz>\n</hash>\n"
 > Hash.from_xml(hash.to_xml)
 => {"hash"=>{"foo"=>"bar", "baz"=>"qux"}}

Hash instances also have some added methods that do handy things, like
#stringify_keys / #symbolize_keys and #slice:

 > Hash.from_xml(hash.to_xml)['hash'].symbolize_keys
 => {:foo=>"bar", :baz=>"qux"}
 > hash.stringify_keys
 => {"foo"=>"bar", "baz"=>"qux"}
 > hash.slice(:foo, :bar, :lol)
 => {:foo=>"bar"}

All of Ruby's assorted time classes (Time, Date, DateTime) have some
handy helpers like #beginning_of_month:

 > Time.now
 => 2012-09-09 03:19:45 -0700
 > Time.now.beginning_of_month
 => 2012-09-01 00:00:00 -0700

That one also works for "end_of_X" and replacing month with day, week,
quarter and year.

Also on ruby's time classes, #to_s will take a symbol argument that
tells which predefined format to render it in:

 > Time.now
 => 2012-09-09 03:22:24 -0700
 > Time.now.to_s(:db)
 => "2012-09-09 03:22:29"
 > Time.now.to_s(:long)
 => "September 9, 2012"
 > Date.today
 => Sun, 09 Sep 2012
 > Date.today.to_s(:db)
 => "2012-09-09"
 > Date.today.to_s(:long)
 => "September 9, 2012"

There are a few of these predefined, and you can even define your own
formats using #strftime strings or by passing a proc (example borrowed
from rails docs):

 > Date::DATE_FORMATS[:month_and_year] = "%B %Y"
 => "%B %Y"
 > Date::DATE_FORMATS[:short_ordinal] = lambda { |date|
date.strftime("%B #{date.day.ordinalize}") }
 => #<Proc:0x000000056284c8@(irb):25 (lambda)>
 > Date.today.to_s(:month_and_year)
 => "September 2012"
 > Date.today.to_s(:short_ordinal)
 => "September 9th"