This plugin adds basic support for foreign keys, by providing some additional schema statements as well as integration into the standard schema dumper.
Currently, mysql and postgresql connection adapters are supported.
Via standard git clone:
git clone git://github.com/dwalters/foreign_keys.git vendor/plugins/foreign_keys
Via rails plugin (requires 2.1):
script/plugin install git://github.com/dwalters/foreign_keys.git
Just place the appropriate statements in your migrations. The simplest example is:
add_foreign_key :orders, :user_id
The usual rails conventions are used to deduce that this should result in a
foreign key from the orders.user_id column to the users.id column
Of course, you may specify these values explicitly too, and will need to when the conventions don't match exactly:
add_foreign_key :articles, :author_id, :references => :users
Some other options of note:
references: the name of the referenced tablekeys: the corresponding column name(s) in the referenced tableon_delete/on_update: one of:restrict,:set_null,:cascadename: the name to assign to the foreign key constraint
Note that recent mysql versions will create an index on the referenced column(s) if one does not already exist.
You may wish to check the documentation for further options.
You can remove foreign keys by name:
remove_foreign_key :orders, :name => "index_orders_on_user_id"
Or the name can be deduced if you used standard conventions when you created it:
remove_foreign_key :orders, :user_id
This will not automatically remove any indexes.
The usual rake targets for db:schema:dump, db:schema:load, and db:reset
should all work as desired.
Dan Walters
http://github.com/dwalters/foreign_keys
Max Lapshin -- PostgreSQL support