A better optimisation, as suggested by TomH.

[rails.git] / app / models / relation_member.rb

diff --git a/app/models/relation_member.rb b/app/models/relation_member.rb
index 79102853e9c218a362a52eedd5acf30b52233e19..fbaf89dafd937d30871f30fed7c3bb5ab87e1d20 100644 (file)
--- a/app/models/relation_member.rb
+++ b/app/models/relation_member.rb
@@ -1,30 +1,24 @@
 class RelationMember < ActiveRecord::Base
   set_table_name 'current_relation_members'
-
-  # problem with RelationMember is that it may link to any one 
-  # object (a node, a way, another relation), and belongs_to is
-  # not flexible enough for that. So we do this, which is ugly,
-  # but fortunately rails won't actually run the SQL behind that
-  # unless someone really accesses .node, .way, or
-  # .relation - which is what we do below based on member_type.
-  # (and no: the :condition on belongs_to doesn't work here as
-  # it is a condition on the *referenced* object not the 
-  # *referencing* object!)
   
-  belongs_to :node, :foreign_key => "member_id"
-  belongs_to :way, :foreign_key => "member_id"
-  belongs_to :relation, :foreign_key => "member_id"
+  set_primary_keys :id, :sequence_id
+  belongs_to :member, :polymorphic => true
+  belongs_to :relation, :foreign_key => :id
+
+  def after_find
+    self[:member_class] = self.member_type.classify
+  end
 
-  # so we define this "member" function that returns whatever it
-  # is.
- 
-  def member()
-    return (member_type == "node") ? node : (member_type == "way") ? way : relation
+  def after_initialize
+    self[:member_class] = self.member_type.classify unless self.member_type.nil?
   end
 
-  # NOTE - relations are SUBJECTS of memberships. The fact that nodes, 
-  # ways, and relations can be the OBJECT of a membership,
-  # i.e. a node/way/relation can be referenced throgh a
-  # RelationMember object, is NOT modelled in rails, i.e. these links
-  # have to be resolved manually, on demand. 
+  def before_save
+    self.member_type = self[:member_class].classify
+  end
+
+  def member_type=(type)
+    self[:member_type] = type
+    self[:member_class] = type.capitalize
+  end
 end