| Re: Repository pattern implementation that knows nothing (Jon Snow) about the database table and column names [message #186372 is a reply to message #186366] |
Wed, 09 July 2014 06:36  |
Goran
Messages: 38
Registered: January 2011
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On 8.7.2014. 17:47, qissolol(at)gmail(dot)com wrote:
> I've seen around the Internet and Github, implementations for the design pattern Repository that knows about database table and column names. I was think, if I want to work with the database as a plugin, that I can unplug and plug another respecting Open/Closed for the rest of my code, my repository should not know about the column names of the database I'm using. So how to implement this pattern in a way that it can transform the result from the database into a Entity of my domain, without knowing about the database table and column names?
>
> As my main language is PHP, I saw that in Doctrine\ORM you can easily pass different yamls or xmls config files, mapping the column names to property names on the Entity, but... I cant be a hostage of a library implementation, if I want to implement raw PDO, or any other library for my repositories that doesn't make this hydration out-of-the-box, my implementation should do, so how?
>
Yes, it's possible.
Firstly, you need to make a technology-agnostic model (no Doctrine
annotations, etc.), then repository interface.
Later, you can plug in whatever you want. That plugs are implementations...
Let's say, one implementation could be made using Doctrine 2 ORM.
Because your model is tech-agnostic, you can't use annotations to map
it, but nothing stop you to use external XML maps. Beside mapping, you
need to create a repository implementation using Doctrin 2 ORM. Here is
the skeleton of such implementation:
class DoctrineUserRepository implements UserRepository
{
private $doctrineRepository;
public function __construct(EntityRepository $doctrineRepository)
{
$this->doctrineRepository = $doctrineRepository;
}
// ...
}
Only things you should keep in mind are technology limitations - you
can't make naive model (without investigating Doctrine ORM limitations)
because you will encounter those limitations later (inheritance quirks,
compostite primary keys, value objects...)
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