Add attr_readonly to specify columns that are skipped during a normal ActiveRecord #save operation. Closes #6896 [dcmanges]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@7693 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

5 files changed, 85 insertions, 17 deletions

diff --git a/activerecord/CHANGELOG b/activerecord/CHANGELOG
index 9372adb583..f470fe7b84 100644
--- a/activerecord/CHANGELOG
+++ b/activerecord/CHANGELOG
@@ -1,5 +1,16 @@
 *2.0.0 [Preview Release]* (September 29th, 2007) [Includes duplicates of changes from 1.14.2 - 1.15.3]
 
+* Add attr_readonly to specify columns that are skipped during a normal ActiveRecord #save operation. Closes #6896 [dcmanges]
+
+  class Comment < ActiveRecord::Base
+    # Automatically sets Article#comments_count as readonly.
+    belongs_to :article, :counter_cache => :comments_count
+  end
+
+  class Article < ActiveRecord::Base
+    attr_readonly :approved_comments_count
+  end
+
 * Make size for has_many :through use counter cache if it exists.  Closes #9734 [xaviershay]
 
 * Remove DB2 adapter since IBM chooses to maintain their own adapter instead.  [Jeremy Kemper]
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index e269775fd5..1ec7d6021f 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -841,7 +841,11 @@ module ActiveRecord
           module_eval(
             "before_destroy '#{reflection.name}.class.decrement_counter(\"#{cache_column}\", #{reflection.primary_key_name})" +
             " unless #{reflection.name}.nil?'"
-          )          
+          )
+          
+          module_eval(
+            "#{reflection.class_name}.send(:attr_readonly,\"#{cache_column}\".intern) if defined?(#{reflection.class_name})"
+          )
         end
       end
 
diff --git a/activerecord/lib/active_record/base.rb b/activerecord/lib/active_record/base.rb
index a4ebaf4e93..34685a78e1 100755
--- a/activerecord/lib/active_record/base.rb
+++ b/activerecord/lib/active_record/base.rb
@@ -636,6 +636,15 @@ module ActiveRecord #:nodoc:
         read_inheritable_attribute("attr_accessible")
       end
 
+       # Attributes listed as readonly can be set for a new record, but will be ignored in database updates afterwards.
+       def attr_readonly(*attributes)
+         write_inheritable_array("attr_readonly", attributes - (readonly_attributes || []))
+       end
+
+       # Returns an array of all the attributes that have been specified as readonly.
+       def readonly_attributes
+         read_inheritable_attribute("attr_readonly")
+       end
 
       # If you have an attribute that needs to be saved to the database as an object, and retrieved as the same object, 
       # then specify the name of that attribute using this method and it will be handled automatically.  
@@ -1953,7 +1962,7 @@ module ActiveRecord #:nodoc:
       def update
         connection.update(
           "UPDATE #{self.class.table_name} " +
-          "SET #{quoted_comma_pair_list(connection, attributes_with_quotes(false))} " +
+          "SET #{quoted_comma_pair_list(connection, attributes_with_quotes(false, false))} " +
           "WHERE #{connection.quote_column_name(self.class.primary_key)} = #{quote_value(id)}",
           "#{self.class.name} Update"
         )
@@ -2008,6 +2017,15 @@ module ActiveRecord #:nodoc:
           raise "Declare either attr_protected or attr_accessible for #{self.class}, but not both."
         end
       end
+      
+      # Removes attributes which have been marked as readonly.
+      def remove_readonly_attributes(attributes)
+        unless self.class.readonly_attributes.nil?
+          attributes.delete_if { |key, value| self.class.readonly_attributes.include?(key.gsub(/\(.+/,"").intern) }
+        else
+          attributes
+        end
+      end
 
       # The primary key and inheritance column can never be set by mass-assignment for security reasons.
       def attributes_protected_by_default
@@ -2018,13 +2036,14 @@ module ActiveRecord #:nodoc:
 
       # Returns copy of the attributes hash where all the values have been safely quoted for use in
       # an SQL statement.
-      def attributes_with_quotes(include_primary_key = true)
-        attributes.inject({}) do |quoted, (name, value)|
+      def attributes_with_quotes(include_primary_key = true, include_readonly_attributes = true)
+        quoted = attributes.inject({}) do |quoted, (name, value)|
           if column = column_for_attribute(name)
             quoted[name] = quote_value(value, column) unless !include_primary_key && column.primary
           end
           quoted
         end
+        include_readonly_attributes ? quoted : remove_readonly_attributes(quoted)
       end
 
       # Quote strings appropriately for SQL statements.
diff --git a/activerecord/test/associations_test.rb b/activerecord/test/associations_test.rb
index 59951d47fb..85df401fb1 100755
--- a/activerecord/test/associations_test.rb
+++ b/activerecord/test/associations_test.rb
@@ -1175,6 +1175,24 @@ class BelongsToAssociationsTest < Test::Unit::TestCase
     topic.update_attributes(:title => "37signals")
     assert_equal 1, Topic.find(topic.id)[:replies_count]
   end
+  
+  def test_belongs_to_counter_after_save
+    topic = Topic.create("title" => "monday night")
+    topic.replies.create("title" => "re: monday night", "content" => "football")
+    assert_equal 1, Topic.find(topic.id).send(:read_attribute, "replies_count")
+
+    topic.save
+    assert_equal 1, Topic.find(topic.id).send(:read_attribute, "replies_count")
+  end
+
+  def test_belongs_to_counter_after_update_attributes
+    topic = Topic.create("title" => "37s")
+    topic.replies.create("title" => "re: 37s", "content" => "rails")
+    assert_equal 1, Topic.find(topic.id).send(:read_attribute, "replies_count")
+
+    topic.update_attributes("title" => "37signals")
+    assert_equal 1, Topic.find(topic.id).send(:read_attribute, "replies_count")
+  end
 
   def test_assignment_before_parent_saved
     client = Client.find(:first)
diff --git a/activerecord/test/base_test.rb b/activerecord/test/base_test.rb
index 1883f369c3..4418b8d9e6 100755
--- a/activerecord/test/base_test.rb
+++ b/activerecord/test/base_test.rb
@@ -47,6 +47,10 @@ class TightDescendant < TightPerson
   attr_accessible :phone_number
 end
 
+class ReadonlyTitlePost < Post
+  attr_readonly :title
+end
+
 class Booleantest < ActiveRecord::Base; end
 
 class Task < ActiveRecord::Base
@@ -840,6 +844,19 @@ class BasicsTest < Test::Unit::TestCase
     assert_nil TightDescendant.protected_attributes
     assert_equal [ :name, :address, :phone_number  ], TightDescendant.accessible_attributes
   end
+  
+  def test_readonly_attributes
+    assert_equal [ :title ], ReadonlyTitlePost.readonly_attributes
+    
+    post = ReadonlyTitlePost.create(:title => "cannot change this", :body => "changeable")
+    post.reload
+    assert_equal "cannot change this", post.title
+    
+    post.update_attributes(:title => "try to change", :body => "changed")
+    post.reload
+    assert_equal "cannot change this", post.title
+    assert_equal "changed", post.body
+  end
 
   def test_multiparameter_attributes_on_date
     attributes = { "last_read(1i)" => "2004", "last_read(2i)" => "6", "last_read(3i)" => "24" }
@@ -1222,12 +1239,12 @@ class BasicsTest < Test::Unit::TestCase
   end
 
   def test_increment_attribute
-    assert_equal 1, topics(:first).replies_count
-    topics(:first).increment! :replies_count
-    assert_equal 2, topics(:first, :reload).replies_count
-    
-    topics(:first).increment(:replies_count).increment!(:replies_count)
-    assert_equal 4, topics(:first, :reload).replies_count
+    assert_equal 50, accounts(:signals37).credit_limit
+    accounts(:signals37).increment! :credit_limit
+    assert_equal 51, accounts(:signals37, :reload).credit_limit    
+
+    accounts(:signals37).increment(:credit_limit).increment!(:credit_limit)
+    assert_equal 53, accounts(:signals37, :reload).credit_limit
   end
   
   def test_increment_nil_attribute
@@ -1237,14 +1254,13 @@ class BasicsTest < Test::Unit::TestCase
   end
   
   def test_decrement_attribute
-    topics(:first).increment(:replies_count).increment!(:replies_count)
-    assert_equal 3, topics(:first).replies_count
-    
-    topics(:first).decrement!(:replies_count)
-    assert_equal 2, topics(:first, :reload).replies_count
+    assert_equal 50, accounts(:signals37).credit_limit
 
-    topics(:first).decrement(:replies_count).decrement!(:replies_count)
-    assert_equal 0, topics(:first, :reload).replies_count
+    accounts(:signals37).decrement!(:credit_limit)
+    assert_equal 49, accounts(:signals37, :reload).credit_limit
+  
+    accounts(:signals37).decrement(:credit_limit).decrement!(:credit_limit)
+    assert_equal 47, accounts(:signals37, :reload).credit_limit
   end
   
   def test_toggle_attribute