Pacecar adds named_scope methods and other common functionality to ActiveRecord classes via database column introspection.

Pacecar automatically includes the Pacecar::Helpers module into all ActiveRecord::Base classes.

To get all Pacecar functionality, you need to “include Pacecar” in your class.

To get some subset (for example, only the state functionality), you can do something like “include Pacecar::State” to get only the module(s) you want.

Assuming a database schema…

class CreateSchema < ActiveRecord::Migration
  def self.up
    create_table :users, :force => true do |t|
      t.boolean :admin, :default => false, :null => false
      t.datetime :approved_at
      t.datetime :rejected_at
      t.string :first_name
      t.string :last_name
      t.text :description
      t.timestamps
    end
    create_table :posts, :force => true do |t|
      t.string :owner_type
      t.integer :owner_id
      t.string :publication_state
      t.string :post_type
      t.timestamps
    end
    create_table :comments, :force => true do |t|
      t.integer :user_id
      t.text :description
      t.timestamps
    end
  end
end

And some basic model declarations…

class User < ActiveRecord::Base
  include Pacecar
  has_many :posts, :as => :owner
  has_many :comments
  has_many :articles
  has_ranking :comments
  has_recent_records :comments
  has_recent_records :articles, :comments
end

class Post < ActiveRecord::Base
  include Pacecar
  PUBLICATION_STATES = %w(Draft Submitted Rejected Accepted)
  TYPES = %w(Free Open Private Anonymous PostModern)
  belongs_to :owner, :polymorphic => true
  has_state :publication_state
  has_state :post_type, :with => TYPES
  has_polymorph :owner
end

class Comment < ActiveRecord::Base
  include Pacecar
  belongs_to :user
end

class Article < ActiveRecord::Base
  belongs_to :user
end

Records where approved_at is not null, or where it is null…

User.approved_at_present
User.approved_at_missing

Records where first_name is not null, or where it is null…

User.first_name_present
User.first_name_missing

Records ordered by first_name (default to ‘asc’, can specify to override)…

User.by_first_name
User.by_first_name(:asc)
User.by_first_name(:desc)

Records where an attribute matches a search term (column LIKE “%term%”)…

User.first_name_matches('John')

Records where an attribute starts or ends with a search term…

User.first_name_starts_with('A')
User.first_name_ends_with('a')

Records where any non-state text or string column matches term…

User.search_for('test')

Records where any of a list of columns match the term…

User.search_for 'test', :on => [:first_name, :last_name]

Records where all of a list of columns match the term…

User.search_for 'test', :on => [:first_name, :last_name], :require => :all

Records that are all admins or non-admins…

User.admin
User.not_admin

The “balance” (count of true minus false for column in question)…

User.admin_balance

Records approved before or after certain times…

User.approved_at_before(5.days.ago)
User.approved_at_after(4.weeks.ago)

Records with approved_at in the past or future…

User.approved_at_in_past
User.approved_at_in_future

Records with approved_at inside or outside of two times…

User.approved_at_inside(10.days.ago, 1.day.ago)
User.approved_at_outside(2.days.ago, 1.day.ago)

Records with certain year, month or day…

User.approved_at_in_year(2000)
User.approved_at_in_month(01)
User.approved_at_in_day(01)

Records with a duration (time delta between two columns) of, over or under a certain number of days…

User.with_duration_of(14, :approved_at, :rejected_at)
User.with_duration_over(14, :approved_at, :rejected_at)
User.with_duration_under(14, :approved_at, :rejected_at)

Records which have an owner_type of User…

Post.for_owner_type(User)

Records with the most and least associated records…

User.maximum_comments
User.minimum_comments

Records with associated records since a certain time…

User.recent_comments_since(2.days.ago)
User.recent_comments_and_posts_since(3.days.ago)
User.recent_comments_or_posts_since(4.days.ago)

Records which are in a particular state, or not in a state…

Post.publication_state_draft
Post.post_type_not_open

Query methods on instances to check state…

Post.first.publication_state_draft?
Post.last.post_type_not_open?

First x records…

User.limited(10)

Because these are all named_scope, you can combine them.

To get all users that have a first_name set, who are admins and approved more than 2 weeks ago, ordered by their first name…

User.first_name_present.admin.approved_at_before(2.weeks.ago).by_first_name

To get the top 10 commenters…

User.maximim_comments.limited(10)

Pacecar is free software, and may be redistributed under the terms specified in the MIT-LICENSE file.