= HasManyExclusiveConditions

Author::    Jason L Perry (http://ambethia.com, http://paint.itred.org)
Copyright:: Copyright (c) 2007 Jason L Perry
License::   MIT
URI::       http://subvert.itred.org/has_many_exclusive_conditions

== Description

This plugin adds an :exclusive_conditions option to ActiveRecord's has_many
association. This let's you express ideas that are otherwise impossible with
the default rails generated sql.

=== Caveat Emptor!

You need to becareful with how rails interpolates your string to create
the generated SQL. If you plan on using instance variables or methods in the
fragment, be sure to use an UNinterpolated ruby string (ie, %q or single
quotes). Also, be aware of boolean values and other things that are not always
database agnostic. ActiveRecord methods like +quote_value+ can be your friend.

== Example

In this example, we want to create an association for a User's record, or if
that user is an admin, all records will be included.

  User.has_many :accessible_records, :exclusive_conditions => %q(records.user_id = #{id} OR #{is_admin})

Will generate SQL like:

  SELECT * FROM things WHERE (`things`.user_id = 1 OR true)
  
Instead of the SQL from regular +:condition+ option:

  SELECT * FROM things WHERE (`things`.user_id = 1) AND (`things`.user_id = 1 OR true)