Add support for specifying comments for tables, columns, and indexes.

Comments are specified in migrations, stored in database itself (in its schema),
and dumped into db/schema.rb file.

This allows to generate good documentation and explain columns and tables' purpose
to everyone from new developers to database administrators.

For PostgreSQL and MySQL only. SQLite does not support comments at the moment.

See docs for PostgreSQL: http://www.postgresql.org/docs/current/static/sql-comment.html
See docs for MySQL: http://dev.mysql.com/doc/refman/5.7/en/create-table.html

1 files changed, 4 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/schema_dumper.rb b/activerecord/lib/active_record/schema_dumper.rb
index affcd9aed1..bc4adb4ed7 100644
--- a/activerecord/lib/active_record/schema_dumper.rb
+++ b/activerecord/lib/active_record/schema_dumper.rb
@@ -138,6 +138,9 @@ HEADER
           table_options = @connection.table_options(table)
           tbl.print ", options: #{table_options.inspect}" unless table_options.blank?
 
+          comment = @connection.table_comment(table)
+          tbl.print ", comment: #{comment.inspect}" if comment
+
           tbl.puts " do |t|"
 
           # then dump all non-primary key columns
@@ -209,6 +212,7 @@ HEADER
             statement_parts << "where: #{index.where.inspect}" if index.where
             statement_parts << "using: #{index.using.inspect}" if index.using
             statement_parts << "type: #{index.type.inspect}" if index.type
+            statement_parts << "comment: #{index.comment.inspect}" if index.comment
 
             "  #{statement_parts.join(', ')}"
           end