Fakey - foreign keys support for ActiveRecord migrations

Before resorting to write yet another foreign key plugin I tried foreign_key_migrations (no longer available) and foreigner, but they have annoying shortcomings. foreign_key_migrations assumes every column ending on _id to be a foreign key and tries to infer the table name, which in my case was not the right one. foreigner doesn't let you declare foreign key in create_table block, instead you have to call explicitly add_foreign_key(:comments, :posts) after it. Not quite helpful for tables containing a lot of foreign keys.

Fakey is fully tested by directly inspecting schema in the database and supports both MySQL and PostgreSQL.

Example

Fakey hooks foreign keys to the standard belongs_to and references methods in migrations.

# Standard usage
create_table :books do |t|
  t.belongs_to :author
end
# => CREATE TABLE "books" ("id" serial primary key, "author_id" integer REFERENCES "authors")

# Table name specified explicitly
create_table :poems do |t|
  t.belongs_to :author, :references => :poets
end
# => CREATE TABLE "poems" ("id" serial primary key, "author_id" integer REFERENCES "poets")

# Column name specified explicitly (if you don't want _id suffix)
create_table :books do |t|
  t.belongs_to :author, :column => :author
end
# => CREATE TABLE "books" ("id" serial primary key, "author" integer REFERENCES "books")

# Non-integer primary key (for those with legacy databases) - this only works in PostgreSQL now!
execute "CREATE TABLE authors( name VARCHAR(255) PRIMARY KEY)"
create_table :books do |t|
  t.belongs_to :author_name, :column => :author_name, :references => :authors, :type => :string
end
# => CREATE TABLE "books" ("id" serial primary key, "author_name" VARCHAR(255) REFERENCES "authors")

# Non-primary key (for those with legacy databases)
create_table :authors do |t|
  t.integer :ssid
end
execute("ALTER TABLE authors ADD UNIQUE(ssid)") # note that add_index doesn't create constraint!
create_table :books do |t|
  t.belongs_to :author_ssid, :column => :author_ssid, :references => :authors, :referenced_column => :ssid
end
# => CREATE TABLE "books" ("id" serial primary key, "author_ssid" integer REFERENCES "authors"(ssid))


# Changing table too
change_table :atuhors do |t|
  t.belongs_to :author
end

Compatibility

Rails: 3.2+

PostgreSQL 7.0+

MySQL 5.0+