Comments on: migrating to datamapper 0.9 – unique indexes http://odwks.com/2008/06/migrating-to-datamapper-09-unique-indexes/ > old dudes who know startups Fri, 28 Oct 2011 23:10:42 +0000 hourly 1 http://wordpress.org/?v=3.3 By: jhancock http://odwks.com/2008/06/migrating-to-datamapper-09-unique-indexes/comment-page-1/#comment-2 jhancock Sat, 13 Sep 2008 09:00:41 +0000 http://odwks.com/?p=14#comment-2 comment by John W Higgins: There’s another little trick to the :unique_index concept - if you use a symbol as opposed to true then you can create multiple named indexes with multiple fields. Extending your example slightly (but not realistically)…. <code>class User include DataMapper::Resource property :id, Integer, :serial => true property :email, String, :unique_index => true property :display_name, String, :unique_index => :names property :full_name, String, :unique_index => :names property :address String, :unique_index => :bob </code> Will get indexes generated along the lines of… <code>Indexes: “users_pkey” PRIMARY KEY, btree (id) “unique_index_users_names” UNIQUE, btree (display_name, full_name) “unique_index_users_email” UNIQUE, btree (email) “unique_index_users_bob” UNIQUE, btree (address)</code> comment by John W Higgins:
There’s another little trick to the :unique_index concept – if you use a symbol as opposed to true then you can create multiple named indexes with multiple fields.

Extending your example slightly (but not realistically)….

class User
include DataMapper::Resource
property :id, Integer, :serial => true
property :email, String, :unique_index => true
property :display_name, String, :unique_index => :names
property :full_name, String, :unique_index => :names
property :address String, :unique_index => :bob

Will get indexes generated along the lines of…

Indexes:
“users_pkey” PRIMARY KEY, btree (id)
“unique_index_users_names” UNIQUE, btree (display_name, full_name)
“unique_index_users_email” UNIQUE, btree (email) “unique_index_users_bob” UNIQUE, btree (address)

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