Extract Common Persistance Interfaces

Added the interfaces here https://github.com/doctrine/common/commit/59e6b8c6edcb271622923035b687a063c2b47ce8

I implemented them here in the mongodb-odm https://github.com/doctrine/mongodb-odm/commit/8d02e8439fb6737de1e23e1953a643858a8a6c68

and the ORM https://github.com/doctrine/doctrine2/commit/68a40996841b1dbec3b8de5c1038809e5db512b7

I think we can add a few more methods to ClassMetadata interface that are always gonna exist between the different persistence layers. Let me know what you think and what you want to add.

Jon is working on this.

CouchDB ODM also has DocumentRepositry::findMany(array $ids)
Should we add that to the interface?

No, that method is only on the repository because CouchDB doesn't need persisters (yet). Its not part of the interfaceable public methods.

Not sure I understand. The method is used in DocumentRepository::findBy() as well as in PersistentIdsCollection::load. Seems unnecessary for that method to be public just for this. At any rate imho the method seems convenient and also allows for more efficient access in many RDBMS compared to the generic findBy($criteria) method. So it seems worthwhile adding it.

It doesn't matter what CouchDB uses internally on the DocumentRepository, i don't think this method is particularly useful in another context than CouchDBs use of Collections. In any case the method is just a proxy for findBy(array("id" => array(1, 2, 3, 4, 5, 6))); and i am not sure we need such a method on an interface just for convenience, Repository::find() use-case is much broader.

Actually using findMany($ids) ias clearly more efficient in CouchDB than using findBy(array("id" => $ids));
The same applies to PHPCR, since going by the node path means you can go via the normal node API, rather than the search API.
So this is already 2 out of 3 examples and I do not know MongoDB enough to tell if they also have some specific API advantage.

Hm, you might be right. Ok, this should be included.

What i am still pondering with is adding array $orderBy and $firstResult, $maxResults to findOneBy() and findBy() and findAll().

@Jon: Would this be possible for MongoDB?

It would not be possible for all use-cases in CouchDB, but for some it can work.

Just a super trivial pull to add this to the interface:
https://github.com/doctrine/common/pull/11

also wondering if we want to include the idgenerator API in the interface?

Hm yes, i think that is necessary. At least the differentation between assigned and auto-generated ids is relevant for metadata queries.

Yes, findMany() is possible with MongoDB.

I think it would just be a proxy to:

public function findMany(array $ids)
{
    return $this->findBy(array('_id' => array('$in' => $ids)));
}

Hm, What is this syntax? This is not conforming to the EntityRepository interface.

The only two allowed methods are:

IN Query:

$ids = array(...);
findBy(array('_id' => $ids)); 

Equals = Query:

$ids = 1234;
findBy(array('_id' => $id)); 

Everything else is not portable accross implementations and should only be able through DocumentManager::CreateQuery* sort of apis.

To find by things in MongoDB you just give an array of key => value pairs. It gets passed straight through to MongoDB. The $in syntax is just soemthing mongodb supports. It's not anything specific to Doctrine.

i want to heat this topic back up:

• findMany()
• id generator API