如何在Doctrine MongoDB中更新嵌入式文档？

Question

I have a document that has a document embedded. When I create an object for the first time everything works fine, but when I try to update a document, the embedded document does not get updated.

/** @MongoDB\Document */
class DocumentA
{
    /** @MongoDB\EmbedOne(targetDocument="DocumentB") **/
    protected $docB;

    /** @MongoDB\String */
    protected $valueA;
}

/** @MongoDB\EmbeddedDocument */
class DocumentB
{
    /** @MongoDB\String */
    protected $valueB;
}

In my application I query for a document, update the values and persist them to the data store.

// Variant A – Does not work
$document = ... // find from data store
$document->setValueA('Hello World');
$document->getDocB()->setValueB('foo baz');

$om->persist($document);
$om->flush();

If I do not update the embedded document, but set a new one everything works fine:

// Variant B - Does work
$document = ... // find from data store
$document->setValueB('Hello World 2');
$document->setDocB(new DocumentB());
$document->getDocB()->setValueB('foo baz 2');

$om->persist($document);
$om->flush();

As I said, Variant B works fine. However, in my application the documents are more complex and it would be impractical for me to create a new object for the embedded document every time I have to update it. Is there a method to tell Doctrine ODM to look at the values of an embedded document to decide if it should be updated?

Answer 1

I faced exactly the same issue. It turns out the UnitOfWork seems to fail in computing the changesets of documents with other documents embedded, though I have not been able to figure out why... As a result, when when i compare the actual value and the original one, unit of work shows the same value for both. Speaking with your Variant A, when you

$document->getDocB()->setValueB('foo baz');

Unit of work shows "foo baz" for both the old and the new value and will not recognize it as aa change and will therefor not update it.

Anyway, this leeds to a workaround:

$document = ... // find from data store
$document->setValueA('Hello World');
$docB = $document->getDocB();
$docB->setValueB('foo baz');
$om->detach($docB);
$om->persist($document);
$om->flush();

This makes the unit of work recognize the docB of $document as a newly set document and will flush it as expected.

Answer 2

MongoDB has only atomic operations. You have options: 1. Query the document, find the apropriate subdocument, update the whole document or its part. Pros: easy logic Cons: non-atomic 2. Use positional $ operator is your subdocuments are in list.