Add implementation of Countable for CachingIterator

[Branlute]

Q	A
Type	bug
BC Break	no
Fixed issues

Summary

Hi,

I currently use MongoDB with Doctrine, as well as ElasticSearch through FOSElascitaBundle.
When trying to use EnqueueBundle to speed up the populate command https://github.com/FriendsOfSymfony/FOSElasticaBundle/blob/master/doc/cookbook/speed-up-populate-command.md, I encountered an error.

The enqueue command for elastica makes a count of getCurrentPageResults:
https://github.com/php-enqueue/enqueue-elastica-bundle/blob/master/Queue/PopulateProcessor.php#L61

Unfortunately, Doctrine's CachingIterator does not implement countable unlike Mongo's https://github.com/mongodb/mongo-php-library/blob/master/src/Model/CachingIterator.php which generates an error.

So I added the implementation of countable in CachingIterator in order to be able to use Enqueue with FOSElastica and MongoDB via Doctrine.

Thank you very much for the library 😉

[malarzm]

@Branlute thanks for the PR! Could you please add a test to https://github.com/doctrine/mongodb-odm/blob/2.4.x/tests/Doctrine/ODM/MongoDB/Tests/Functional/Iterator/CachingIteratorTest.php so the ability to call \count on an iterator won't be lost? Please squash the test addition into original commit.

Thank you very much for the library wink

🍻

[malarzm]

@Branlute thanks for the updates! We'll need to take care of CI first before merging as something is really off with it. I'll merge this whenever I'll have a chance :)

[malarzm]

@Branlute we've managed to get checks back to shape (sorry for the long time wait :( ). May I ask you to rebase your PR atop newly created 2.5.x branch?

[Branlute]

@malarzm I rebase my branch with 2.5.x and change the target branch to 2.5.x

[IonBazan]

Thanks @Branlute! 🚀