description.md

WildcardSearch is a module from Ennova's Envision application used with permission. The purpose of this module is to allow users to search fields of all records of a model for certain keywords.

The usage example is in usage.rb for this gist and the code uses ARel extensively.

The includes method is from ARel and does a LEFT OUTER JOIN on the association specified's table, providing we fetch fields from that table in the where. For more information see this post: http://ruby.ryanbigg.com/post/1468788928/left-outer-join-with-arel

usage.rb

class Event < ActiveRecord::Base
  include WildcardSearch
  belongs_to :originator, :class_name => "User"
end

Event.includes(:originator).wildcard_search(:name, :description, :originator => [:username], text)

wildcard_search.rb

module WildcardSearch
  def wildcard_search(*fields)
    # Get what we're looking for
    text_parts = fields.pop.split(/\s/).map { |part| "%#{part}%" }

    cnds = nil
    fields.each do |field|
      field = { self.table_name => [field] } if field.is_a? Symbol
      field.each do |table, columns|
        assoc = reflect_on_association table
        table = if assoc && assoc.macro == :belongs_to
          Table assoc.table_name, :as => "#{assoc.name.to_s.tableize}_#{assoc.table_name}"
        else
          Table table
        end
        columns.each do |column|
          text_parts.each do |part|
            cnd = table[column].matches(part)
            cnds = cnds ? cnds.or(cnd) : cnd
          end
        end
      end
    end

    where(cnds)
  end
end