LARubyConf 2009 - Jeremy Evans - "Sequel"

The next session at the 2009 Los Angeles Ruby Conference (LARubyConf) was Jeremy Evans presenting Sequel, which is a very powerful database toolkit for Ruby.

Ruby originally had adapters for each database. The problem was that each was very database specific. This was a problem due to both SQL differences, as well as API differences.

no behavior

1997 - ruby-postgres was first created.

2000 - DBI

2004 - Active Record
Although AR made things easier, it had strong opinions. These opinions did not always map perfectly to any particular database.

2007 - Sequel

Completely DB independent API.

Example is concatanating strings, which requires a completely different syntax in each flavor of SQL database.

Concise

Optional Behavior

Opinions?

Ruby should be like clay in a child's hands - Matz

Sequel advantages:
- Simple - as possible but no simpler
- Flexible - opinions, not dogma
- Powerful
- Lightweight - 1/2 memory usage as active record
- Well maintained
- Easy to Contribute
- Easy to Understand
- More Fun

Show me the *** code!

require 'seq'
DB = Sequal.sqlite('larun')
DB[:attendees].count
# => 1

DB[:attendees].first
# => {:name ='', :address =>}

Transactions

DB.trans do
  DB[:entry],insert(:account_id => 1)

  ...

end

SQL Loggers

DB.loggers << Logger.new($stdout)

Each DB has its own connection pool

DB[:table].all # or .each

.update(:column => 'value)

.delete

DB[:table] # this is a dataset... like query cursor

Sequel is a functional API, where object methods return copies of themselves.

.select - while columns
.filter
.order

This means you can easily chain function calls, like jQuery. Awesome!

Sequel represents its internal objects using SQL's own internal representations

Sequel has 'core' and 'model'

class Attendee < Sequel::Model
  many_to_one
  one_to_many
  
  
end

Hooks & Validations - got 'em

Sequel it built entirely out of plugins. That sounds interesting, but experience with DataMapper has shown me that too many plugins may not be a good thing. However, I do not have any direct experience with Sequel yet, so this may be a non-issue.

13 - # of database adapters that Sequel supports today

Database graphing

Everything was going so well up to this point. However, Jeremy then tried to do his demo on Windows, just to show that if you are one of the poor souls using Windows, it can still work for you. He failed to account for the quirkiness of conference display adapters, and what that can do to a machine. Oh well, no demo.

That said, I was really impressed by what I heard about Sequel. I think I will have to try it out on something, just to see how it does.