From bfe6a759c25ad02b4bfcb2dd16999d8ba72e2df8 Mon Sep 17 00:00:00 2001
From: David Heinemeier Hansson <david@loudthinking.com>
Date: Thu, 16 Jun 2005 05:35:10 +0000
Subject: Added actual database-changing behavior to collection assigment for
 has_many and has_and_belongs_to_many #1425 [Sebastian Kanthak]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@1428 5ecf4fe2-1ee6-0310-87b1-e25e094e27de
---
 activerecord/lib/active_record/associations.rb         | 18 +++++++++++++++++-
 .../associations/association_collection.rb             | 16 +++++++++++++---
 2 files changed, 30 insertions(+), 4 deletions(-)

(limited to 'activerecord/lib')

diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index 93960f87e4..65549aca0c 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -200,6 +200,8 @@ module ActiveRecord
       # * <tt>collection<<(object, ...)</tt> - adds one or more objects to the collection by setting their foreign keys to the collection's primary key.
       # * <tt>collection.delete(object, ...)</tt> - removes one or more objects from the collection by setting their foreign keys to NULL.  
       #   This will also destroy the objects if they're declared as belongs_to and dependent on this model.
+      # * <tt>collection=objects</tt> - replaces the collections content by deleting and adding objects as appropriate.
+      # * <tt>collection_singular_ids=ids</tt> - replace the collection by the objects identified by the primary keys in +ids+
       # * <tt>collection.clear</tt> - removes every object from the collection. This does not destroy the objects.
       # * <tt>collection.empty?</tt> - returns true if there are no associated objects.
       # * <tt>collection.size</tt> - returns the number of associated objects.
@@ -215,6 +217,8 @@ module ActiveRecord
       # * <tt>Firm#clients</tt> (similar to <tt>Clients.find :all, :conditions => "firm_id = #{id}"</tt>)
       # * <tt>Firm#clients<<</tt>
       # * <tt>Firm#clients.delete</tt>
+      # * <tt>Firm#clients=</tt>
+      # * <tt>Firm#client_ids=</tt>
       # * <tt>Firm#clients.clear</tt>
       # * <tt>Firm#clients.empty?</tt> (similar to <tt>firm.clients.size == 0</tt>)
       # * <tt>Firm#clients.size</tt> (similar to <tt>Client.count "firm_id = #{id}"</tt>)
@@ -463,6 +467,8 @@ module ActiveRecord
       #   (collection.concat_with_attributes is an alias to this method).
       # * <tt>collection.delete(object, ...)</tt> - removes one or more objects from the collection by removing their associations from the join table.  
       #   This does not destroy the objects.
+      # * <tt>collection=objects</tt> - replaces the collections content by deleting and adding objects as appropriate.
+      # * <tt>collection_singular_ids=ids</tt> - replace the collection by the objects identified by the primary keys in +ids+
       # * <tt>collection.clear</tt> - removes every object from the collection. This does not destroy the objects.
       # * <tt>collection.empty?</tt> - returns true if there are no associated objects.
       # * <tt>collection.size</tt> - returns the number of associated objects.
@@ -474,6 +480,8 @@ module ActiveRecord
       # * <tt>Developer#projects<<</tt>
       # * <tt>Developer#projects.push_with_attributes</tt>
       # * <tt>Developer#projects.delete</tt>
+      # * <tt>Developer#projects=</tt>
+      # * <tt>Developer#project_ids=</tt>
       # * <tt>Developer#projects.clear</tt>
       # * <tt>Developer#projects.empty?</tt>
       # * <tt>Developer#projects.size</tt>
@@ -634,6 +642,10 @@ module ActiveRecord
             association.replace(new_value)
             association
           end
+
+          define_method("#{Inflector.singularize(association_name)}_ids=") do |new_value|
+            send("#{association_name}=", association_class_name.constantize.find(new_value))
+          end
         end
 
         def require_association_class(class_name)
@@ -687,7 +699,11 @@ module ActiveRecord
               instance_variable_set("@#{association_name}", association)
             end
 
-            association.send(constructor, attributees, replace_existing)
+            if association_proxy_class == HasOneAssociation
+              association.send(constructor, attributees, replace_existing)
+            else
+              association.send(constructor, attributees)
+            end
           end
         end
 
diff --git a/activerecord/lib/active_record/associations/association_collection.rb b/activerecord/lib/active_record/associations/association_collection.rb
index 1eac8a2a0b..4495d92151 100644
--- a/activerecord/lib/active_record/associations/association_collection.rb
+++ b/activerecord/lib/active_record/associations/association_collection.rb
@@ -1,3 +1,5 @@
+require 'set'
+
 module ActiveRecord
   module Associations
     class AssociationCollection < AssociationProxy #:nodoc:
@@ -83,11 +85,19 @@ module ActiveRecord
         collection.inject([]) { |uniq_records, record| uniq_records << record unless uniq_records.include?(record); uniq_records }
       end
 
+      # Replace this collection with +other_array+
+      # This will perform a diff and delete/add only records that have changed.
       def replace(other_array)
-        other_array.each{ |val| raise_on_type_mismatch(val) }
+        other_array.each { |val| raise_on_type_mismatch(val) }
+
+        load_target
+        other   = other_array.size < 100 ? other_array : other_array.to_set
+        current = @target.size < 100 ? @target : @target.to_set
 
-        @target = other_array
-        @loaded = true
+        @owner.transaction do
+          delete(@target.select { |v| !other.include?(v) })
+          concat(other_array.select { |v| !current.include?(v) })
+        end
       end
 
       private
-- 
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