ORM is Object-relational mapping
This is a broad term for a number of techniques that usually boil down to treating a row in a database table as an object.
ActiveRecord, part of Ruby on Rails, is probably the best-known ORM in the scripting language world right now. Hibernate and Torque are well-known and popular in the Java world.
Data Mapper is one of the patterns for doing ORM, or ORM-like-things.
With Data Mapper, Mapper objects sit between the database layer and domain objects and do the translation while keeping them separated.
Horde is one of the oldest open-source PHP projects, encompassing an application framework and over 50 applications.
Horde on the Rampage is a catchphrase for the rapid-application building focus of Horde 4.
This was initially called Catalyst when it started out in Chuck's head, but Catalyst (written in Perl) was released before anything got written down.
Rdo is Rampage Data Objects. It's not RDO.
Other PHP implementations require XML (Propel), overload objects for both the model and row instances (DB_DataObject), require defining the database schema with PHPDoc annotations (ezPDO), etc.
This is mixing objects with classes, and it's because PHP doesn't have late static binding:
$b = new Book; $books = $b->find(...);
Should be:
$books = Book::find(...);
Be as light as possible, but no lighter
Leave managing the database to the developer (DBA) or another tool (MDB2_Schema)
Smart usage of PHP 5 features and interfaces
Broad database support, with enough SQL abstraction for things that should be simple like LIMIT
Rdo is still beta software (like GMail!). The API is getting quite stable, but it is not frozen yet.
pear channel-discover pear.horde.org pear install horde/Rdo
CREATE TABLE users (
id bigserial NOT NULL,
name varchar(255),
phone varchar(20),
created int,
updated int,
PRIMARY KEY (id)
);
Two core concepts: Mappers and entity objects.
Mappers implement the DataMapper part of Rdo, and always extend Horde_Rdo_Mapper. They need to know how to connect to the database, and know about any relationships with other objects.
Entity objects are the "O" in ORM. They always extend Horde_Rdo_Base, and the most they know about the database is how to find a Mapper object.
You don't always want to load everything from the database in one go - blobs, large text fields, complicated and rarely used relationships (second cousins twice removed - they just need to show up at weddings and funerals).
SELECT pr.description, pr.id, pr.product_id, pr.brand_id, p.special, p.case_price, p.piece_price,
SUM(o.units) AS units, SUM(o.extra) AS extra, pr.units_per_case, o.locked, pr.min_ord_qty,
(SUM(o.units) + SUM(o.extra)) AS units_wanted, pr.piece_size, o.catalog_id,
floor((SUM(o.units) + SUM(o.extra)) / pr.units_per_case) AS cases_ordered
FROM coop_orders o INNER JOIN coop_prices p ON o.product_id = p.product_id
INNER JOIN coop_products pr ON o.product_id = pr.id
GROUP BY pr.id, o.locked
ORDER BY o.locked, pr.description;
Can't create a primary key on a view in MySQL; can't always have a primary key. Composite primary keys can help, but that doesn't help us with views.
Instead of inspecting the database for the Horde_Rdo_Model object:
# rdo-model.php coop_group_order
<?php
class Coop_group_order_Model extends Horde_Rdo_Model {
...
Compare the output to the output for the users table. Only thing missing is 'key':
If you need it, it's there: