From 3ac5229f32433405628dbca0ec190f7df5013841 Mon Sep 17 00:00:00 2001
From: Nerian <siotopo@gmail.com>
Date: Thu, 18 May 2017 18:55:50 +0200
Subject: Document support for composite primary keys
---
.../connection_adapters/abstract/schema_statements.rb | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
(limited to 'activerecord/lib')
diff --git a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
index 13629dee7f..6015c38ab5 100644
--- a/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
+++ b/activerecord/lib/active_record/connection_adapters/abstract/schema_statements.rb
@@ -188,6 +188,8 @@ module ActiveRecord
# The name of the primary key, if one is to be added automatically.
# Defaults to +id+. If <tt>:id</tt> is false, then this option is ignored.
#
+ # If an array is passed, a composite primary key will created.
+ #
# Note that Active Record models will automatically detect their
# primary key. This can be avoided by using
# {self.primary_key=}[rdoc-ref:AttributeMethods::PrimaryKey::ClassMethods#primary_key=] on the model
@@ -241,6 +243,23 @@ module ActiveRecord
# label varchar
# )
#
+ # ====== Create a composite primary key
+ #
+ # create_table(:orders, primary_key: [:product_id, :client_id]) do |t|
+ # t.belongs_to :product
+ # t.belongs_to :client
+ # end
+ #
+ # generates:
+ #
+ # CREATE TABLE order (
+ # product_id integer NOT NULL,
+ # client_id integer NOT NULL
+ # );
+ #
+ # ALTER TABLE ONLY "orders"
+ # ADD CONSTRAINT orders_pkey PRIMARY KEY (product_id, client_id);
+ #
# ====== Do not add a primary key column
#
# create_table(:categories_suppliers, id: false) do |t|
--
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