#2 Dynamic find_by Methods

Mar 06, 2007 | 1 minute | Active Record

Shorten simple finds considerably and improve readability by using the dynamic find_all_by and find_by methods.

Click to Play Video ▶

Download:
mp4Full Size H.264 Video (2.55 MB)
m4vSmaller H.264 Video (1.88 MB)
webmFull Size VP8 Video (5.08 MB)
ogvFull Size Theora Video (3.06 MB)

This is a really useful way to do a Find in Rails. Below is a Task model that searches for tasks that haven’t been completed (i.e. the complete column is false).

          ruby
        
class TaskController < ApplicationController
  def incomplete
    @tasks = Task.find(:all, :conditions => ['complete = ?', false])
  end

  def last_incomplete 
    @task = Task.find(:first, :conditions => ['complete =?', false], :order => 'created_at DESC')
  end
end

There is a better way to achieve this with find_by_all. Just replace

          ruby
        
@tasks = Task.find(:all, :conditions => ['complete = ?', false])

with

          ruby
        
@tasks = Task.find_all_by_complete(false)

If you just want to find one Task then use find_by, so to find the latest incomplete task the line

          ruby
        
@task = Task.find(:first, :conditions => ['complete =?', false], :order => 'created_at DESC')

becomes

          ruby
        
@task = Task.find_by_complete(false, :order => 'created_at DESC')

The find_by method takes the order parameter just like the find method does.