Undoctrine doctrine specification

[peter-gribanov]

Reopen PR #82

This is not the final implementation. So far this is only a concept.

Benefits:

• Specifications do not know anything about Doctrine;
• You can implement your transformers of specifications;
• For example, I added transformers for Doctrine ODM MongoDB;
• You can write a transformer for a specific function of the database. For example for a map/reduce functions.

Doctrine ODM MongoDB docs.

Disadvantages:

• We break back compatibility;
• For each custom specification, you need to write your own transformer.

Usage

Join

Join condition can be used only from parameters of specification:

$spec = new SpecificationCollection([
    new Equals('published', false),
    new InnerJoin('user', 'u', InnerJoin::ON, new AndX(
        new Equals('banned', false),
        new LessOrEqualThan('birthday', new \DateTime('-18 year'))
    ))
]);

Map Reduce

Example specification:

class Foo implements Map, Reduce
{
    /**
     * @return string
     */
    public function getMap()
    {
        return 'function() {
            emit(this.userId, 1);
        }';
    }

    /**
     * @return string
     */
    public function getReduce()
    {
        return 'function(k, vals) {
            var sum = 0;
            for (var i in vals) {
                sum += vals[i];
            }
            return sum;
        }';
    }
}

[peter-gribanov]

If we want to divide the structure of the specifications and apply them to queries, then it is better to make additional repositories which, as plugins, expand the basic functionality.

There is a problem with the fact that the query interface for ORM and ODM is very different. Accordingly, the structure of the specifications will also differ. Perhaps, it is worth concentrating only on ORM.

@Nyholm are you interested in developing this idea?

[peter-gribanov]

Also, i think it's better to make this change as a separate repository.
I believe that this repository should remain connected with Doctrine.