raises an exception on habtm join table inserts if join table contains a primary key. Caches this check to save time on subsequent inserts.

[#2086 state:committed]

Signed-off-by: Jeremy Kemper <jeremy@bitsweat.net>

1 files changed, 14 insertions, 2 deletions

diff --git a/activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb b/activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb
index b5d8de2544..d91c555dad 100644
--- a/activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb
+++ b/activerecord/lib/active_record/associations/has_and_belongs_to_many_association.rb
@@ -1,6 +1,11 @@
 module ActiveRecord
   module Associations
     class HasAndBelongsToManyAssociation < AssociationCollection #:nodoc:
+      def initialize(owner, reflection)
+        super
+        @primary_key_list = {}
+      end
+
       def create(attributes = {})
         create_record(attributes) { |record| insert_record(record) }
       end
@@ -17,6 +22,12 @@ module ActiveRecord
         @reflection.reset_column_information
       end
 
+      def has_primary_key?
+        return @has_primary_key unless @has_primary_key.nil?
+        @has_primary_key = (ActiveRecord::Base.connection.supports_primary_key? &&
+          ActiveRecord::Base.connection.primary_key(@reflection.options[:join_table]))
+      end
+
       protected
         def construct_find_options!(options)
           options[:joins]      = @join_sql
@@ -29,8 +40,9 @@ module ActiveRecord
         end
 
         def insert_record(record, force = true, validate = true)
-          if ActiveRecord::Base.connection.supports_primary_key? && ActiveRecord::Base.connection.primary_key(@reflection.options[:join_table])
-            raise ActiveRecord::ConfigurationError, "Primary key is not allowed in a has_and_belongs_to_many join table (#{@reflection.options[:join_table]})."
+          if has_primary_key?
+            raise ActiveRecord::ConfigurationError,
+              "Primary key is not allowed in a has_and_belongs_to_many join table (#{@reflection.options[:join_table]})."
           end
 
           if record.new_record?