Refactored docs to use adders/removers

[wouterj]

Q	A
Doc fix?	yes
New docs?	yes
Applies to	2.1+
Fixed tickets	#1057

This is the first draw to fix this document for 2.1. I have not tested the code yet, that's why I called it a WIP.

[wouterj]

The code is tested on 2.1 and it works.

I have one question though. There is a note that says:

First, unless you iterate over all of the new Tag objects and
call $em->persist($tag) on each, you'll receive an error from
Doctrine:

A new entity was found through the relationship
Acme\TaskBundle\Entity\Task#tags that was not configured to
cascade persist operations for entity...

I tested it with Doctrine 2.3.1 and I got no error.

[stof]

@wouterj Are you adding new elements in the collection or only editing exsting ones ?

[stof]

And are you cascading the persist on the relation ? If yes, it is indeed useless to persist explicitly each tag

[stof]

You need to define both addTag and removeTag. If one of them is missing, the setter for the collection will be used when using by_reference => false, not the adder and remover for each element

[wouterj]

fixed

[weaverryan]

Ping @wouterj! I'm waiting for answers on Stof's questions before moving on :)

[wouterj]

Sorry for my delay on this. I need to finish some PRs now! :)

@stof was correct, the entity I used was cascading the persist action. (I just used your entity, so I wasn't aware of that)

[wouterj]

@weaverryan I've updated the article, I think it's ready now

[weaverryan]

Nice work @wouter - I moved the new text further down in the article, but I have very few changes otherwise.

Tweaks at sha: ec49d58

Thanks!