Skip to content

devwout/foreign_key_migrations

master
Switch branches/tags

Name already in use

A tag already exists with the provided branch name. Many Git commands accept both tag and branch names, so creating this branch may cause unexpected behavior. Are you sure you want to create this branch?
Code
This branch is 1 commit ahead of azimux:master.

Latest commit

 

Git stats

Files

Permalink
Failed to load latest commit information.
Type
Name
Latest commit message
Commit time
lib
 
 
 
 
 
 
 
 
 
 
 
 
 
 
= Foreign Key Migrations

Foreign Key Migrations is a plugin that automatically generates foreign-key
constraints when creating tables. It uses SQL-92 syntax and as such should be
compatible with most databases that support foreign-key constraints.

In the simplest case, the plugin assumes that if you have a column named
+customer_id+ that you want a foreign-key constraint generated that references
the +id+ column in the +customers+ table:

  create_table :orders do |t|
    t.column :customer_id, :integer, :null => false
    ...
  end

If you have multiple columns referencing a table or for whatever reason, your
column name isn't the same as the referenced table name, you can use the
<code>:references</code> option:

  create_table :orders do |t|
    t.column :ordered_by_id, :integer, :null => false, :references => :customers
    ...
  end

If you have a column with a name ending in +_id+ for which you do not wish a
foreign-key to be generated, you can use <code>:references => nil</code>:

  create_table :orders do |t|
    t.column :external_id, :integer, :null => false, :references => nil
    ...
  end

Sometimes you may (for legacy reasons) need to reference a primary key column that is
named something other than +id+. In this case you can specify the name of the column:

  create_table :orders do |t|
    t.column :ordered_by_pk, :integer, :null => false, :references => [:customers, :pk]
    ...
  end

You also have the option of specifying what to do on delete/update using
<code>:on_delete</code>/<code>:on_update</code>, respectively to one of:
<code>:cascade</code>; <code>:restrict</code>; and <code>:set_null</code>:

  create_table :orders do |t|
    t.column :customer_id, :integer, :on_delete => :set_null, :on_update => :cascade
    ...
  end

If your database supports it (for example PostgreSQL) you can also mark the constraint as deferrable:

  create_table :orders do |t|
    t.column :customer_id, :integer, :deferrable => true
    ...
  end

By convention, if a column is named +parent_id+ it will be treated as a circular reference to
the table in which it is defined.

Sometimes you may (for legacy reasons) need to name your primary key column such that it
would be misinterpreted as a foreign-key (say for example if you named the primary key
+order_id+). In this case you can manually create the primary key as follows:

  create_table :orders, :id => false do |t|
    ...
    t.primary_key :order_id, :references => nil
  end

There is also a generator for creating foreign keys on a database that currently has none:

  ruby script/generate foreign_key_migration

The plugin fully supports and understands the following active-record
configuration properties:

* <code>config.active_record.pluralize_table_names</code>
* <code>config.active_record.table_name_prefix</code>
* <code>config.active_record.table_name_suffix</code>

=== Dependencies

* RedHill on Rails Core (redhillonrails_core).

=== See Also

* Foreign Key Associations (foreign_key_associations).

=== License

This plugin is copyright 2006 by RedHill Consulting, Pty. Ltd. and is released
under the MIT license.

About

Snapshot of the (no longer supported?) foreign_key_migrations plugin

Resources

License

Stars

Watchers

Forks

Releases

No releases published

Packages

No packages published

Languages

  • Ruby 100.0%