From 65871b5b8dfb85cadf25dfc6e55b8281b7f92b99 Mon Sep 17 00:00:00 2001
From: =?utf-8?q?Guillermo=20=C3=81lvarez=20Fern=C3=A1ndez?= <guillermo@cientifico.net>
Date: Tue, 9 Sep 2008 14:33:32 +0200
Subject: [PATCH] Added ActiveRecord.each (and collect and map)

---
 activerecord/lib/active_record.rb      |    2 +
 activerecord/lib/active_record/each.rb |   91 ++++++++++++++++++++++++++++++++
 activerecord/test/cases/each_test.rb   |   52 ++++++++++++++++++
 3 files changed, 145 insertions(+), 0 deletions(-)
 create mode 100644 activerecord/lib/active_record/each.rb
 create mode 100644 activerecord/test/cases/each_test.rb

diff --git a/activerecord/lib/active_record.rb b/activerecord/lib/active_record.rb
index a6bbd6f..2a59e08 100644
--- a/activerecord/lib/active_record.rb
+++ b/activerecord/lib/active_record.rb
@@ -52,6 +52,7 @@ require 'active_record/serialization'
 require 'active_record/attribute_methods'
 require 'active_record/dirty'
 require 'active_record/dynamic_finder_match'
+require 'active_record/each'
 
 ActiveRecord::Base.class_eval do
   extend ActiveRecord::QueryCache
@@ -71,6 +72,7 @@ ActiveRecord::Base.class_eval do
   include ActiveRecord::Reflection
   include ActiveRecord::Calculations
   include ActiveRecord::Serialization
+  include ActiveRecord::Each
 end
 
 require 'active_record/connection_adapters/abstract_adapter'
diff --git a/activerecord/lib/active_record/each.rb b/activerecord/lib/active_record/each.rb
new file mode 100644
index 0000000..979a489
--- /dev/null
+++ b/activerecord/lib/active_record/each.rb
@@ -0,0 +1,91 @@
+
+module ActiveRecord 
+  module Each #:nodoc:
+    def self.included(base)
+      base.extend(ClassMethods)
+    end
+
+    module ClassMethods
+
+      
+      # Each goes througt all entries in a model, without loading all
+      # You can pass to it any parameter like find. See find for options you can pass
+      # If you set an :order, you will get a slow query in tables with a lot of rows
+      #
+      # ==== Examples:
+      #
+      #   # Goes throught all users wich name starts by g
+      #   User.each (:conditions => "users.name LIKE 'g%'") do |u|
+      #     puts u.name
+      #   end
+      #
+      def each(*args,&block)
+        options = args.extract_options!
+        validate_find_options(options)
+        set_readonly_option!(options)
+
+        # if we're passed order then fast mode MAY not work, so we'll stick
+        # with the slow mode
+        if options[:order]
+          slow_each(options,&block)
+        else
+          fast_each(options, &block) # for unsorted querys
+        end
+      end
+
+      # Invokes block once for each element of self. Creates a new array containing the values returned by the block
+      #
+      # ==== Example:
+      #
+      #   #Get password from md5hash
+      #   clean_password = User.map { |u| magic_recover_password(u.md5) }
+      #
+      def map(*args)
+        options = args.extract_options!
+        validate_find_options(options)
+        set_readonly_option!(options)
+
+        results = Array.new
+        each(options) do |i|
+          results << yield(i)
+        end
+        results
+      end
+
+      # Collect is an alias for map
+      alias_method :collect, :map
+      
+    private
+      def slow_each(options)
+        count(options).times do |i|
+          yield(find_initial(options.merge({:offset => i})))
+        end      
+      end
+
+      # because :offset can be quite slow for large tables as really the DB
+      # still has to execute the query and then seek into the query to return 
+      # you the row you want.
+      # using the primary_key allows us to piggy back on the index
+      def fast_each(options)
+        i=minimum("#{table_name}.#{primary_key}", options)
+        
+        # not all the backends always sort primay_key columns so do it manuall
+        options.update(:order => "#{table_name}.#{primary_key} ASC")
+        
+        i=minimum("#{table_name}.#{primary_key}", options) or return
+        # first the first object by id
+        yield(o=find_one(i, {}))
+        # as long as we keep finding objects, keep going
+        while o
+          with_scope(:find => {:conditions => [ "#{table_name}.#{primary_key} > ?", i]} ) do
+            if o=find_initial(options)
+              i=o.send primary_key
+              yield(o) 
+            end
+          end
+        end
+      end
+    end
+  end
+end
+
diff --git a/activerecord/test/cases/each_test.rb b/activerecord/test/cases/each_test.rb
new file mode 100644
index 0000000..9355117
--- /dev/null
+++ b/activerecord/test/cases/each_test.rb
@@ -0,0 +1,52 @@
+require "cases/helper"
+require 'models/topic'
+require 'models/reply'
+require 'models/task'
+require 'models/course'
+require 'models/category'
+require 'models/post'
+
+class EachTest < ActiveRecord::TestCase
+  fixtures :tasks, :topics, :categories, :posts, :categories_posts
+  def setup
+    @posts = Post.all(:order => "id asc")
+    @total = Post.count
+  end
+  
+  def test_each_method
+    assert Post.respond_to?(:each)
+  end
+  
+  def test_map_method
+    assert Post.respond_to?(:map)
+    assert Post.respond_to?(:collect)
+    assert_equal @posts, Post.map {|p| p }
+  end
+
+  def test_each_with_conditions
+    i=0
+    Post.each(:conditions => {:title => "sti comments"} ) {|u| i+=1 }
+    assert_equal 1, i
+  end
+
+  def test_each_without_conditions
+    i=0
+    Post.each {|u| i+=1 }
+    assert_equal @total, i
+  end
+
+  def test_backwards_primary_key_map
+    assert_equal Post.find(:all, :order => "id desc"), Post.map(:order => "id desc") { |p| p }
+    assert_equal Post.find(:all, :order => "id desc"), Post.map(:order => "posts.id desc") { |p| p }
+  end
+
+  def test_map_method_with_conditions
+    assert_equal [4], Post.map(:conditions => {:title => "sti comments"}) {|u| u.id}
+  end
+
+  def test_empty_result_set_dont_throw_exception
+    assert_nothing_raised (ActiveRecord::RecordNotFound) do
+      Post.each(:conditions => "id = -1") { |u| u.name }
+    end
+  end
+end
-- 
1.5.6.3