ruby script/plugin install http://svn.protocool.com/public/plugins/values_of

USAGE:

values_of(colspec, options = {}, &block)

* colspec can be a:

Symbol - in which case you are selecting that column and (unless you pass a block) you want the in-built rails type-casting to turn the raw text sql result into the relevant type.

String - an sql expression you want to use for the :select portion of your query. Note that if you pass a String then values_of won't try to automatically type_cast your returned values. See the info about &block below.

* options are anything normally accepted by ActiveRecord::Base#find.

* &block is an optional block that will be collect()ed on your returned string
values.

Note that &block overrides any implicit type_cast()ing that would be done if you pass a Symbol as a colspec.

EXAMPLES:

Project.values_of(:created_on, :limit => 10) 
# SELECT projects.`created_on` FROM projects LIMIT 10
# [Date, Date, Date, ... ]

Project.values_of('created_on', :limit => 10)
# SELECT created_on FROM projects LIMIT 10
# ["2006-01-24", "2006-02-21", ....]

Project.values_of("distinct DATE_FORMAT(created_on,'%Y-%m-1')", :limit => 10)
# SELECT distinct DATE_FORMAT(created_on,'%Y-%m-1') FROM projects LIMIT 10
# ["2006-01-1", "2006-02-1", "2006-03-1", ....]

Project.values_of("distinct DATE_FORMAT(created_on,'%Y-%m-1')", :limit => 10) do |raw_val|
  raw_val.to_date
end
# SELECT distinct DATE_FORMAT(created_on,'%Y-%m-1') FROM projects LIMIT 10
# [Date, Date, Date, ... ]

User.find(1).projects.values_of(:id)
# SELECT projects.`id` FROM projects WHERE (projects.user_id = 1)
[1, 8, 16, ...]

There is currently no advanced documentation for this plugin.