push alter table add column sql in to the schema modification visitor

2 files changed, 30 insertions, 9 deletions

diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
index 922a544e81..7f0be28080 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_definitions.rb
@@ -262,12 +262,7 @@ module ActiveRecord
       end
       alias :belongs_to :references
 
-      private
-      def create_column_definition(name, type)
-        ColumnDefinition.new name, type
-      end
-
-      def new_column_definition(name, type, options)
+      def new_column_definition(name, type, options) # :nodoc:
         column = create_column_definition name, type
         limit = options.fetch(:limit) do
           native[type][:limit] if native[type].is_a?(Hash)
@@ -281,6 +276,11 @@ module ActiveRecord
         column
       end
 
+      private
+      def create_column_definition(name, type)
+        ColumnDefinition.new name, type
+      end
+
       def primary_key_column_name
         primary_key_column = columns.detect { |c| c.primary_key? }
         primary_key_column && primary_key_column.name
@@ -291,6 +291,23 @@ module ActiveRecord
       end
     end
 
+    class AlterTable # :nodoc:
+      attr_reader :add
+
+      def initialize(td)
+        @td  = td
+        @add = nil
+      end
+
+      def name; @td.name; end
+
+      def add_column(name, type, options)
+        name = name.to_s
+        type = type.to_sym
+        @add = @td.new_column_definition(name, type, options)
+      end
+    end
+
     # Represents an SQL table in an abstract way for updating a table.
     # Also see TableDefinition and SchemaStatements#create_table
     #
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 08e8d3ca20..6631a278ab 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -355,9 +355,9 @@ module ActiveRecord
       # Adds a new column to the named table.
       # See TableDefinition#column for details of the options you can use.
       def add_column(table_name, column_name, type, options = {})
-        add_column_sql = "ALTER TABLE #{quote_table_name(table_name)} ADD #{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)
+        at = create_alter_table table_name
+        at.add_column(column_name, type, options)
+        execute schema_creation.accept at
       end
 
       # Removes the given columns from the table definition.
@@ -829,6 +829,10 @@ module ActiveRecord
         TableDefinition.new native_database_types, name, temporary, options
       end
 
+      def create_alter_table(name)
+        AlterTable.new create_table_definition(name, false, {})
+      end
+
       def update_table_definition(table_name, base)
         Table.new(table_name, base)
       end