Foreign Keys Plugin
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
Adding Foreign Keys
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
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 table
keys: the corresponding column name(s) in the referenced table
on_update: one of
name: 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.
Removing Foreign Keys
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
should all work as desired.
Max Lapshin -- PostgreSQL support