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 3d689098b5907..a5cc3bf091b6b 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 @@ -9,6 +9,14 @@ def create!(attributes = {}) create_record(attributes) { |record| insert_record(record, true) } end + def columns + @reflection.columns(@reflection.options[:join_table], "#{@reflection.options[:join_table]} Columns") + end + + def reset_column_information + @reflection.reset_column_information + end + protected def construct_find_options!(options) options[:joins] = @join_sql @@ -32,8 +40,6 @@ def insert_record(record, force=true) if @reflection.options[:insert_sql] @owner.connection.insert(interpolate_sql(@reflection.options[:insert_sql], record)) else - columns = @owner.connection.columns(@reflection.options[:join_table], "#{@reflection.options[:join_table]} Columns") - attributes = columns.inject({}) do |attrs, column| case column.name.to_s when @reflection.primary_key_name.to_s @@ -103,7 +109,7 @@ def construct_scope # clause has been explicitly defined. Otherwise you can get broken records back, if, for example, the join column also has # an id column. This will then overwrite the id column of the records coming back. def finding_with_ambiguous_select?(select_clause) - !select_clause && @owner.connection.columns(@reflection.options[:join_table], "Join Table Columns").size != 2 + !select_clause && columns.size != 2 end private diff --git a/activerecord/lib/active_record/reflection.rb b/activerecord/lib/active_record/reflection.rb index dbff4f24d6d3c..1937abdc83b70 100644 --- a/activerecord/lib/active_record/reflection.rb +++ b/activerecord/lib/active_record/reflection.rb @@ -198,6 +198,14 @@ def counter_cache_column end end + def columns(tbl_name, log_msg) + @columns ||= klass.connection.columns(tbl_name, log_msg) + end + + def reset_column_information + @columns = nil + end + def check_validity! end diff --git a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb index b5bedf37044c7..c7458e109673e 100644 --- a/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb +++ b/activerecord/test/cases/associations/has_and_belongs_to_many_associations_test.rb @@ -770,4 +770,15 @@ def test_association_proxy_transaction_method_starts_transaction_in_association_ end end end + + def test_caching_of_columns + david = Developer.find(1) + # clear cache possibly created by other tests + david.projects.reset_column_information + assert_queries(1) { david.projects.columns; david.projects.columns } + # and again to verify that reset_column_information clears the cache correctly + david.projects.reset_column_information + assert_queries(1) { david.projects.columns; david.projects.columns } + end + end