Fill in reference document about overriding each part of a bundle

[weaverryan]

See the new entry introduced in sha: 8c97795

I think much of it will just be a reference (links to to other places), while some topics (because it's hard or impossible to override), should be discussed

[weaverryan]

I've made some progress on this issue (as you can see, each section is short, and just points elsewhere), but there are several other areas that we can still cover. Many of those are sitting in the document and are waiting for your contribution :)

[userfriendly]

If I may I would like to ping you guys regarding the "Entities & Entity mapping" section in that document. Got lots and lots of questions about this - it doesn't seem to be covered in the documentation, and in the IRC channel I get confusing and contradicting suggestions about it.

[wouterj]

Related PR: #2333

[xabbuh]

Doctrine added support to override attributes and so on in one of the latest version. Maybe we can use that?

[wouterj]

Doctrine 2.3.x is used since Symfony 2.1, so we can use it.

[stof]

AttributeOverride can be used to overwrite the mapping of an inherited field. So it makes it easier when a bundle provides a mapped superclass.
But overriding an entity of a bundle is still impossible.

[xabbuh]

That's right, but do you think that's a reason not to mention the already existing possibilities? Even if it's only one sentence like

It is not possible to override an entity of bundle. However, if a bundle provides a mapped superclass one can override attributes and associations.

and link it to the Doctrine documentation.

[wouterj]

@xabbuh I'm 👍 for that, not finished documentation is worse.

[stof]

@xabbuh sure it can be mentionned, but not as a way to overwrite entities

[DHorchler]

Hello everybody,
why not mention that Sympatch can be an alternative to override any part of a bundle, including entities, and is not even limited to PHP code?
https://github.com/DHorchler/SympatchBundle

[wouterj]

I didn't look at the Sympatch bundle yet, but if it can be the solution for overriden bundle parts, I'm 👍 for it. I think including relevant and great bundles in the documentation is a usefull evolution.

[stof]

This bundle is a hack IMO. It modifies the content of the vendor bundles, which does not play well with vendor updates