Simplify a number of object model methods

app/models/node.rb

@@ -196,13 +196,7 @@ class Node < ActiveRecord::Base
   end
 
   def tags
-    unless @tags
+    @tags ||= Hash[self.node_tags.collect { |t| [t.k, t.v] }]
-      @tags = {}
-      self.node_tags.each do |tag|
-        @tags[tag.k] = tag.v
-      end
-    end
-    @tags
   end
 
   def tags=(t)

app/models/old_node.rb

@@ -80,14 +80,7 @@ class OldNode < ActiveRecord::Base
   end
 
   def tags
-    unless @tags
+    @tags ||= Hash[self.old_tags.collect { |t| [t.k, t.v] }]
-      @tags = Hash.new
-      self.old_tags.each do |tag|
-        @tags[tag.k] = tag.v
-      end
-    end
-    @tags = Hash.new unless @tags
-    @tags
   end
 
   def tags=(t)

app/models/old_relation.rb

@@ -60,24 +60,13 @@ class OldRelation < ActiveRecord::Base
   end
 
   def members
-    unless @members
+    @members ||= self.old_members.collect do |member|
-      @members = Array.new
+      [member.member_type, member.member_id, member.member_role]
-      self.old_members.order(:sequence_id).each do |m|
-        @members += [[m.member_type,m.member_id,m.member_role]]
     end
   end
-    @members
-  end
 
   def tags
-    unless @tags
+    @tags ||= Hash[self.old_tags.collect { |t| [t.k, t.v] }]
-      @tags = Hash.new
-      self.old_tags.each do |tag|
-        @tags[tag.k] = tag.v
-      end
-    end
-    @tags = Hash.new unless @tags
-    @tags
   end
 
   def members=(s)

app/models/old_way.rb

@@ -65,24 +65,11 @@ class OldWay < ActiveRecord::Base
   end
 
   def nds
-    unless @nds
+    @nds ||= self.old_nodes.order(:sequence_id).collect { |n| n.node_id }
-      @nds = Array.new
-      self.old_nodes.order(:sequence_id).each do |nd|
-        @nds += [nd.node_id]
-      end
-    end
-    @nds
   end
 
   def tags
-    unless @tags
+    @tags ||= Hash[self.old_tags.collect { |t| [t.k, t.v] }]
-      @tags = Hash.new
-      self.old_tags.each do |tag|
-        @tags[tag.k] = tag.v
-      end
-    end
-    @tags = Hash.new unless @tags
-    @tags
   end
 
   def nds=(s)

app/models/relation.rb

@@ -147,13 +147,7 @@ class Relation < ActiveRecord::Base
   end
 
   def tags
-    unless @tags
+    @tags ||= Hash[self.relation_tags.collect { |t| [t.k, t.v] }]
-      @tags = Hash.new
-      self.relation_tags.each do |tag|
-        @tags[tag.k] = tag.v
-      end
-    end
-    @tags
   end
 
   def members=(m)

app/models/way.rb

@@ -136,23 +136,11 @@ class Way < ActiveRecord::Base
   end 
 
   def nds
-    unless @nds
+    @nds ||= self.way_nodes.collect { |n| n.node_id }
-      @nds = Array.new
-      self.way_nodes.each do |nd|
-        @nds += [nd.node_id]
-      end
-    end
-    @nds
   end
 
   def tags
-    unless @tags
+    @tags ||= Hash[self.way_tags.collect { |t| [t.k, t.v] }]
-      @tags = {}
-      self.way_tags.each do |tag|
-        @tags[tag.k] = tag.v
-      end
-    end
-    @tags
   end
 
   def nds=(s)