add a pg visitor for dealing with schema modification

1 files changed, 21 insertions, 4 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
index 3bc61c5e0c..766b5f07b1 100644
--- a/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb
@@ -1,6 +1,26 @@
 module ActiveRecord
   module ConnectionAdapters
     class PostgreSQLAdapter < AbstractAdapter
+      class SchemaCreation < AbstractAdapter::SchemaCreation
+        private
+
+        def visit_AlterTable(o)
+          sql = "ALTER TABLE #{quote_table_name(o.name)} "
+
+          if col = o.add
+            sql_type = type_to_sql(col.type.to_sym, col.limit, col.precision, col.scale)
+            sql << "ADD COLUMN #{quote_column_name(col.name)} #{sql_type}"
+            add_column_options!(sql, column_options(col))
+          end
+
+          sql
+        end
+      end
+
+      def schema_creation
+        SchemaCreation.new self
+      end
+
       module SchemaStatements
         # Drops the database specified on the +name+ attribute
         # and creates it again using the provided +options+.
@@ -337,10 +357,7 @@ module ActiveRecord
         # See TableDefinition#column for details of the options you can use.
         def add_column(table_name, column_name, type, options = {})
           clear_cache!
-          add_column_sql = "ALTER TABLE #{quote_table_name(table_name)} ADD COLUMN #{quote_column_name(column_name)} #{type_to_sql(type, options[:limit], options[:precision], options[:scale])}"
-          add_column_options!(add_column_sql, options)
-
-          execute add_column_sql
+          super
         end
 
         # Changes the column of a table.