breaking classes up in to respective files

1 files changed, 76 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/associations/class_methods/join_dependency/join_part.rb b/activerecord/lib/active_record/associations/class_methods/join_dependency/join_part.rb
new file mode 100644
index 0000000000..64d751344d
--- /dev/null
+++ b/activerecord/lib/active_record/associations/class_methods/join_dependency/join_part.rb
@@ -0,0 +1,76 @@
+module ActiveRecord
+  module Associations
+    module ClassMethods
+      class JoinDependency # :nodoc:
+        # A JoinPart represents a part of a JoinDependency. It is an abstract class, inherited
+        # by JoinBase and JoinAssociation. A JoinBase represents the Active Record which
+        # everything else is being joined onto. A JoinAssociation represents an association which
+        # is joining to the base. A JoinAssociation may result in more than one actual join
+        # operations (for example a has_and_belongs_to_many JoinAssociation would result in
+        # two; one for the join table and one for the target table).
+        class JoinPart # :nodoc:
+          # The Active Record class which this join part is associated 'about'; for a JoinBase
+          # this is the actual base model, for a JoinAssociation this is the target model of the
+          # association.
+          attr_reader :active_record
+
+          delegate :table_name, :column_names, :primary_key, :reflections, :sanitize_sql, :arel_engine, :to => :active_record
+
+          def initialize(active_record)
+            @active_record = active_record
+            @cached_record = {}
+          end
+
+          def ==(other)
+            raise NotImplementedError
+          end
+
+          # An Arel::Table for the active_record
+          def table
+            raise NotImplementedError
+          end
+
+          # The prefix to be used when aliasing columns in the active_record's table
+          def aliased_prefix
+            raise NotImplementedError
+          end
+
+          # The alias for the active_record's table
+          def aliased_table_name
+            raise NotImplementedError
+          end
+
+          # The alias for the primary key of the active_record's table
+          def aliased_primary_key
+            "#{aliased_prefix}_r0"
+          end
+
+          # An array of [column_name, alias] pairs for the table
+          def column_names_with_alias
+            unless defined?(@column_names_with_alias)
+              @column_names_with_alias = []
+
+              ([primary_key] + (column_names - [primary_key])).each_with_index do |column_name, i|
+                @column_names_with_alias << [column_name, "#{aliased_prefix}_r#{i}"]
+              end
+            end
+
+            @column_names_with_alias
+          end
+
+          def extract_record(row)
+            Hash[column_names_with_alias.map{|cn, an| [cn, row[an]]}]
+          end
+
+          def record_id(row)
+            row[aliased_primary_key]
+          end
+
+          def instantiate(row)
+            @cached_record[record_id(row)] ||= active_record.send(:instantiate, extract_record(row))
+          end
+        end
+      end
+    end
+  end
+end