如何通过引用的文档查询嵌入的文档？

Question

I'm using Doctrine ODM and am having trouble querying embedded documents by a referenced document.

Consider the follow documents:

<?php

/** @Document */
class TopCategory 
{

    /** EmbedMany(targetDocument="SubCategory") */
    private $subCategories;

}

/** @EmbeddedDocument */
class SubCategory 
{

    /** ReferenceMany(targetDocument="Product") */
    private $products;

}


/** @Document */
class Product
{

    /** @String */
    private $name;

}

Now I am wondering how I could find a TopCategory (or SubCategory) by product, I've tried a few different ways to achieve this, one method works but is a bit hackish.

First way, doesn't work:

$category = $dm->createQueryBuilder('TopCategory')
    ->field('subCategories.products')->includesReferenceTo($someProduct)
    ->getQuery()->execute();
// ... gives Doctrine\ODM\MongoDB\MongoDBException: No mapping found for field 'subCategories.products' in class 'TopCategory'.'

Second way, doesn't work:

$category = $dm->createQueryBuilder('SubCategory')
    ->field('products')->includesReferenceTo($someProduct)
    ->getQuery()->execute();    
// ... returns null

Third, working workaround:

$category = $dm->createQueryBuilder('SubCategory')
    ->field('products.$id')->equals(new \MongoId($someProduct->getId()))
    ->getQuery()->execute();    
// .. works, but seems hackish

I am using the latest from GitHub and MognoDB v1.8.0 What's the go with this?

NOTE: Interesting how Doctrine ODM lets you return an embedded document directly.

Answer 1

If you using ReferenceMany or ReferenceOne you can't query by any reference document field, except reference document id, since in mongodb reference document storing like this:

{
  $id: 'id',
  $db: 'referenced_doc_db_name',
  $ref: 'referenced_doc_collection_name'
}

ReferenceOne, ReferenceMany done internally in driver and if need load some document that have references driver send additional requests to load referenced documents.

So, following query not hackish ;):

$category = $dm->createQueryBuilder('SubCategory')
    ->field('products.$id')->equals(new \MongoId($someProduct->getId()))
    ->getQuery()->execute();    
// .. works, but seems hackish

If you need query on some reference field (except id) you should use embedOne or embedMany instead of reference.