diff options
Diffstat (limited to 'guides/source/migrations.textile')
| -rw-r--r-- | guides/source/migrations.textile | 15 |
1 files changed, 13 insertions, 2 deletions
diff --git a/guides/source/migrations.textile b/guides/source/migrations.textile index f663496854..f855072fd8 100644 --- a/guides/source/migrations.textile +++ b/guides/source/migrations.textile @@ -82,6 +82,8 @@ it to default to +false+ for new users, but existing users are considered to have already opted in, so we use the User model to set the flag to +true+ for existing users. +h4. Using the change method + Rails 3.1 makes migrations smarter by providing a new <tt>change</tt> method. This method is preferred for writing constructive migrations (adding columns or tables). The migration knows how to migrate your database and reverse it when @@ -475,7 +477,16 @@ end </ruby> will add an +attachment_id+ column and a string +attachment_type+ column with -a default value of 'Photo'. +a default value of 'Photo'. +references+ also allows you to define an +index directly, instead of using +add_index+ after the +create_table+ call: + +<ruby> +create_table :products do |t| + t.references :category, :index => true +end +</ruby> + +will create an index identical to calling `add_index :products, :category_id`. NOTE: The +references+ helper does not actually create foreign key constraints for you. You will need to use +execute+ or a plugin that adds "foreign key @@ -770,7 +781,7 @@ Both migrations work for Alice. Bob comes back from vacation and: -# Updates the source - which contains both migrations and the latests version of +# Updates the source - which contains both migrations and the latest version of the Product model. # Runs outstanding migrations with +rake db:migrate+, which includes the one that updates the +Product+ model. |