Ambition
An Ambitious ActiveRecord Adapter
I could tell you all about how awesome the internals are, or how fun it was to write, or how it’ll make you rich and famous, but instead I’m just going to show you some examples.
Get It
$ sudo gem install ambitious-activerecord
This will suck in the adapter and its dependencies (ActiveRecord & Ambition). It’s fully usable outside of Rails (I use it in a Camping app or two), as long as you’re riding ActiveRecord.
Now require it in your app:
require 'rubygems' require 'ambition/adapters/active_record'
Examples
Basically, you write your SQL in Ruby. No, not in Ruby. As Ruby.
User.select { |u| u.city == 'San Francisco' }.each do |user| puts user.name end
And that’s it.
The key is that queries aren’t actually run until the data they represent is requested. Usually this is done with what I call a kicker method. You can call them that, too.
Kicker methods are guys like detect
, each
, each_with_index
, map
, entries
,
to_a
, and first
(with no argument). Methods like select
, sort_by
, and first
(with an argument) are not kicker methods and return a Context
object without running any SQL.
Our Context
object has two useful methods: to_s
and to_hash
. With these,
we can check out what exactly we’re building. Not everyone has to_s
,
though. Mostly ignore these methods and treat everything like you normally
would.
See, to_s
:
>> User.select { |m| m.name == 'jon' }.to_s => "SELECT * FROM users WHERE users.name = 'jon'"
See, to_hash
:
>> User.select { |m| m.name == 'jon' }.to_hash => { :conditions => "users.name = 'jon'" }
Equality – select { |u| u.field 'bob' }
User.select { |m| m.name == 'jon' } "SELECT * FROM users WHERE users.name = 'jon'" User.select { |m| m.created_at > 2.days.ago } "SELECT * FROM users WHERE users.created_at > '2007-09-26 20:37:47'" User.select { |m| m.name == 'jon' } "SELECT * FROM users WHERE users.name = 'jon'" User.select { |m| m.name != 'jon' } "SELECT * FROM users WHERE users.name <> 'jon'" User.select { |m| m.name == 'jon' && m.age == 21 } "SELECT * FROM users WHERE (users.name = 'jon' AND users.age = 21)" User.select { |m| m.name == 'jon' || m.age == 21 } "SELECT * FROM users WHERE (users.name = 'jon' OR users.age = 21)" User.select { |m| m.name == 'jon' || m.age == 21 && m.password == 'pass' } "SELECT * FROM users WHERE (users.name = 'jon' OR (users.age = 21 AND users.password = 'pass'))" User.select { |m| (m.name == 'jon' || m.name == 'rick') && m.age == 21 } "SELECT * FROM users WHERE ((users.name = 'jon' OR users.name = 'rick') AND users.age = 21)"
Associations – select { |u| u.field ‘bob’ && u.association.field == ‘bob@bob.com’ }
The to_s
method doesn’t work on associations yet, but that’s okay: they can
still query through ActiveRecord just fine.
User.select do |u| u.email == 'chris@ozmm.org' && u.profile.name == 'chris wanstrath' end.map(&:title) "SELECT users.id AS t0_r0, ... FROM users LEFT OUTER JOIN profiles ON profiles.user_id = users.id WHERE ((users.email = 'chris@ozmm.org' AND profiles.name = 'chris wanstrath'))"
Comparisons – select { |u| u.age > 21 }
User.select { |m| m.age > 21 } "SELECT * FROM users WHERE users.age > 21" User.select { |m| m.age < 21 }.to_s "SELECT * FROM users WHERE users.age < 21" User.select { |m| [1, 2, 3, 4].include? m.id } "SELECT * FROM users WHERE users.id IN (1, 2, 3, 4)"
LIKE and REGEXP (RLIKE) – select { |m| m.name =~ ‘chris’ }
User.select { |m| m.name =~ 'chris' } "SELECT * FROM users WHERE users.name LIKE 'chris'" User.select { |m| m.name =~ 'chri%' } "SELECT * FROM users WHERE users.name LIKE 'chri%'" User.select { |m| m.name !~ 'chris' } "SELECT * FROM users WHERE users.name NOT LIKE 'chris'" User.select { |m| !(m.name =~ 'chris') } "SELECT * FROM users WHERE users.name NOT LIKE 'chris'" User.select { |m| m.name =~ /chris/ } "SELECT * FROM users WHERE users.name REGEXP 'chris'"
#detect
User.detect { |m| m.name == 'chris' } "SELECT * FROM users WHERE users.name = 'chris' LIMIT 1"
LIMITs – first, first(x), [offset, limit], [range], slice
User.select { |m| m.name == 'jon' }.first "SELECT * FROM users WHERE users.name = 'jon' LIMIT 1" User.select { |m| m.name == 'jon' }.first(5) "SELECT * FROM users WHERE users.name = 'jon' LIMIT 5" User.select { |m| m.name == 'jon' }[10, 20] "SELECT * FROM users WHERE users.name = 'jon' LIMIT 10, 20" User.select { |m| m.name == 'jon' }[10..20] "SELECT * FROM users WHERE users.name = 'jon' LIMIT 10, 10"
ORDER – sort_by { |u| u.field }
User.select { |m| m.name == 'jon' }.sort_by { |m| m.name } "SELECT * FROM users WHERE users.name = 'jon' ORDER BY users.name" User.select { |m| m.name == 'jon' }.sort_by { |m| [ m.name, m.age ] } "SELECT * FROM users WHERE users.name = 'jon' ORDER BY users.name, users.age" User.select { |m| m.name == 'jon' }.sort_by { |m| [ m.name, -m.age ] } "SELECT * FROM users WHERE users.name = 'jon' ORDER BY users.name, users.age DESC" User.select { |m| m.name == 'jon' }.sort_by { |m| [ -m.name, -m.age ] } "SELECT * FROM users WHERE users.name = 'jon' ORDER BY users.name DESC, users.age DESC" User.select { |m| m.name == 'jon' }.sort_by { |m| -m.age } "SELECT * FROM users WHERE users.name = 'jon' ORDER BY users.age DESC" User.select { |m| m.name == 'jon' }.sort_by { |m| -m.profiles.title } "SELECT users.id AS t0_r0, ... FROM users LEFT OUTER JOIN profiles ON profiles.user_id = users.id WHERE (users.name = 'jon') ORDER BY profiles.title DESC" User.select { |m| m.name == 'jon' }.sort_by { rand } "SELECT * FROM users WHERE users.name = 'jon' ORDER BY RAND()"
COUNT – select { |u| u.name == ‘jon’ }.size
User.select { |m| m.name == 'jon' }.size "SELECT count(*) AS count_all FROM users WHERE (users.name = 'jon')" >> User.select { |m| m.name == 'jon' }.size => 21
Other Enumerables
These methods perform COUNT operations rather than loading your array into memory. They’re all kickers.
User.any? { |m| m.name == 'jon' } User.all? { |m| m.name == 'jon' } User.select { |m| m.name == 'jon' }.empty?
More Sugar
The downcase
and upcase
methods will map to LOWER and UPPER, respectively.
>> User.select { |m| m.name.downcase =~ 'jon%' }.to_s => "SELECT * FROM users WHERE LOWER(users.name) LIKE 'jon%'"
Quoting
Columns and values will be quoted using ActiveRecord’s quote_column_name and quote methods, if possible.
SELECT * FROM bugs
Found a bug? Sweet. Add it at the Lighthouse.
More information on Ambition:
- Chris Wanstrath [ chris@ozmm.org ]