From 0d2db8a7d112488c93680e88c9beecfdea0a9db5 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Mon, 24 Jan 2005 14:13:10 +0000
Subject: [PATCH] Added Base.update_collection that can update an array of
 id/attribute pairs, such as the ones produced by the recent added support for
 automatic id-based indexing for lists of items #526 [Duane Johnson]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@496 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
---
 activerecord/lib/active_record/base.rb | 43 +++++++++++++++++++++++++-
 activerecord/test/base_test.rb         | 17 ++++++++++
 2 files changed, 59 insertions(+), 1 deletion(-)

diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index 51ee251871..cb13f78f7d 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -372,7 +372,48 @@ def update_all(updates, conditions = nil)
         add_conditions!(sql, conditions)
         return connection.update(sql, "#{name} Update")
       end
-    
+
+      # Updates several records at a time using the pattern of a hash that contains id => {attributes} pairs as contained in +id_and_attributes_pairs+.
+      # If there are certain conditions that must be met in order for the update to occur, an optional block
+      # containing a conditional statement may be used.  Example:
+      #   Person.update_collection { 23 => { "first_name" => "John", "last_name" => "Peterson" },
+      #                        25 => { "first_name" => "Duane", "last_name" => "Johnson" } }
+      #
+      #   # Updates only those records whose first name begins with 'duane' or 'Duane'
+      #   Person.update_collection @params['people'] do |activerecord_object, new_attributes|
+      #     activerecord_object.first_name =~ /^[dD]uane.*/
+      #   end
+      #
+      # The conditional block may also be of use when you have more than one kind of key in the +id_and_attributes_pairs+ hash.
+      # For example, if you have a view that contains form elements of both existing and new records, you might end up with
+      # a hash that looks like this:
+      #   @params['people'] = { "1" => { "first_name" => "Bob", "last_name" => "Schilling" },
+      #                         "2" => { "first_name" => "Joe", "last_name" => "Tycoon" },
+      #                         "new_person" => { "first_name" => "Mary", "last_name" => "Smith" } }
+      # In such a case, you could discriminate against 'updating' the new_person record with the following code:
+      #   Person.update_collection(@params['people']) { |ar, attrs| ar.id.to_i > 0 }
+      #
+      # This works because the to_i method converts all non-integer strings to 0.
+      def update_collection(id_and_attributes_pairs)
+        updated_records = Array.new
+
+        transaction do
+          records = find(id_and_attributes_pairs.keys)          
+          id_and_attributes_pairs.each do |id, attrs|
+            record = records.select { |r| r.id.to_s == id }.first
+
+            # Update each record unless the closure is false
+            if (!block_given? || (block_given? && yield(record, attrs)))
+              record.update_attributes(attrs)
+              updated_records << record
+            end
+          end
+        end
+
+        return updated_records
+      end
+      
+          
       # Destroys the objects for all the records that matches the +condition+ by instantiating each object and calling
       # the destroy method. Example:
       #   Person.destroy_all "last_login < '2004-04-04'"
diff --git a/activerecord/test/base_test.rb b/activerecord/test/base_test.rb
index 02690b7396..2119785caf 100755
--- a/activerecord/test/base_test.rb
+++ b/activerecord/test/base_test.rb
@@ -292,6 +292,23 @@ def test_update_all
     assert_equal "bulk updated again!", Topic.find(2).content
   end
 
+  def test_update_collection
+    ids_and_attributes = { "1" => { "content" => "1 updated" }, "2" => { "content" => "2 updated" } }
+    updated = Topic.update_collection(ids_and_attributes)
+
+    assert_equal 2, updated.size
+    assert_equal "1 updated", Topic.find(1).content
+    assert_equal "2 updated", Topic.find(2).content
+
+    ids_and_attributes["1"]["content"] = "one updated"
+    ids_and_attributes["2"]["content"] = "two updated"
+    updated = Topic.update_collection(ids_and_attributes) { |ar, attrs| ar.id == 1 }
+
+    assert_equal 1, updated.size
+    assert_equal "one updated", Topic.find(1).content
+    assert_equal "2 updated", Topic.find(2).content
+  end
+
   def test_delete_all
     assert_equal 2, Topic.delete_all
   end
-- 
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