Add drop_join_table [#8267]

2 files changed, 17 insertions, 3 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index f1e42dfbbe..bf3155e4e2 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -214,6 +214,17 @@ module ActiveRecord
         end
       end
 
+      # Drops the join table specified by the given arguments.
+      # See create_join_table for details.
+      #
+      # Although this command ignores the block if one is given, it can be helpful
+      # to provide one in a migration's +change+ method so it can be reverted.
+      # In that case, the block will be used by create_join_table.
+      def drop_join_table(table_1, table_2, options = {})
+        join_table_name = find_join_table_name(table_1, table_2, options)
+        drop_table(join_table_name)
+      end
+
       # A block for changing columns in +table+.
       #
       #  # change_table() yields a Table instance
diff --git a/activerecord/lib/active_record/migration/command_recorder.rb b/activerecord/lib/active_record/migration/command_recorder.rb
index d0e54240d3..8dad1b123f 100644
--- a/activerecord/lib/active_record/migration/command_recorder.rb
+++ b/activerecord/lib/active_record/migration/command_recorder.rb
@@ -73,6 +73,7 @@ module ActiveRecord
       [:create_table, :create_join_table, :change_table, :rename_table, :add_column, :remove_column,
         :rename_index, :rename_column, :add_index, :remove_index, :add_timestamps, :remove_timestamps,
         :change_column, :change_column_default, :add_reference, :remove_reference, :transaction,
+        :drop_join_table,
       ].each do |method|
         class_eval <<-EOV, __FILE__, __LINE__ + 1
           def #{method}(*args, &block)          # def create_table(*args, &block)
@@ -93,10 +94,12 @@ module ActiveRecord
         [:drop_table, [args.first]]
       end
 
-      def invert_create_join_table(args)
-        table_name = find_join_table_name(*args)
+      def invert_create_join_table(args, &block)
+        [:drop_join_table, args, block]
+      end
 
-        [:drop_table, [table_name]]
+      def invert_drop_join_table(args, &block)
+        [:create_join_table, args, block]
       end
 
       def invert_rename_table(args)