Question

I am not sure if what I want to do is wrong or just my implementation.

what I want to do is

have multiple “has 1” relationships between a person and addresses

my models are

class Person
  include DataMapper::Resource

  property id,serial
  property name,String

  has 1, :home, :model => 'Address'
  has 1, :office, :model => 'Address'
  has 1, :mail, :model => 'Address'
end

class Address
 include DataMapper::Resource
 property :id,Serial 
 property addr1, String
 property country, String
end

This works fine in code and I can assign and access country of a person

a_person.home.country

but when I save then retireve from DB it does not work. It mixes up home, office and mail addresses

I was hoping to get a structure like

CREATE TABLE `addresses` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `addr1` varchar(50) DEFAULT NULL,
  `country` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`id`)
)

CREATE TABLE `persons` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(50) DEFAULT NULL,
  'home' int(10) unsigned ,
  'office' int(10) unsigned ,
  'mail' int(10) unsigned ,
  PRIMARY KEY (`id`)
) 

what I got was

CREATE TABLE `addresses` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `addr1` varchar(50) DEFAULT NULL,
  `country` varchar(50) DEFAULT NULL,
  `person_id` int(10) unsigned NOT NULL,
  PRIMARY KEY (`id`),
  KEY `index_addresses_person` (`person`)
)

CREATE TABLE `persons` (
  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,
  `name` varchar(50) DEFAULT NULL,
  PRIMARY KEY (`id`)
)

the table structure is not important to me, what I want is that home,office and mail are all the same object type and perferrably are in the same table. It would be nice to be able assign the same Address instance to say, both home and mail and have it stored only once in addresses but referenced twice.

P.S. people and addresses are not the actual underlying object they are just used as a familiar example.

Edit: I may be able to do what I want by putting 4 has n assoc on Address. I will try and edit my answer with the results.

Answer 1

Actually you might want something like this:

class Person
  include DataMapper::Resource

  property :id, Serial
  property :name, String

  belongs_to :home,   :model => Address
  belongs_to :office, :model => Address, :required => false
  belongs_to :mail,   :model => Address, :required => false
end

class Address
  include DataMapper::Resource

  property :id,Serial 
  property :address, String
  property :country, String
end