Added InitializeObject hook

[256dpi]

Hi there!

First of all thanks for this amazing library!

I'm working on a small very opinionated framework that uses struct tags to simplify the declaration of models. I first thought this might get very complicated with api2go as it uses reflect to create new objects internally. But in fact I learned that most actions go either through crud.Find() or crud.FindAll() which allows to setup the object before jsonapi.Marshal() or jsonapi.Unmarshal() is called. The situation that does not allow such access is on a PATCH request. An object gets created with reflect right before passing it to jsonapi.Unmarshal().

TL;DR:
This pull request adds an optional method that can be implemented to get access to the dynamically created object in a PATCH request before jsonapi.Unmarshal() is called. This is necessary to give context to the models in higher frameworks that abstract the jsonapi interfaces.

Please feel free to change the name of the interface and method. ;)

[coveralls]

Coverage increased (+5.5%) to 87.153% when pulling c9b73d5 on 256dpi:object-initializer into 0f0aba6 on manyminds:master.

[wwwdata]

Thanks for the PR. Yes what you are saying makes sense. Im just confused that you mentioned PATCH. You mean POST because you called the potential interface implementation in the Create api route, right? Which makes totally sense because in that, we create a new instance of a struct and then unmarshal into it, which would be the undesired behaviour you are describing.

I currently don't really understand why go 1.4 fails in travis, but I guess it's some golint issues.

I like the interface name, but please squash the fix typo commit into your first, I'll check that the test are working and then we can merge it :)

[wwwdata]

golang/lint#198

Per the README, golint nowadays requires Go 1.5 or later.

ok, hm, let's ditch that old version 1.4 then :D

[sharpner]

I would love if you could add a test using the newly introduced behaviour, and additionally shouldn't the interface be something like ObjectInitializer to keep golangs interface guidelines?

[256dpi]

Thanks for the fast responses.

@wwwdata Ups, yes I mean POST of course.
@sharpner You're right, that makes more sense. I will add a test in a moment.

[wwwdata]

once #248 is merged you can just rebase on it for the tests to work

[coveralls]

Coverage increased (+5.7%) to 87.299% when pulling af9c788 on 256dpi:object-initializer into 0f0aba6 on manyminds:master.

[wwwdata]

👍 just one more rebase before merge

[coveralls]

Coverage increased (+0.05%) to 87.299% when pulling 619ee96 on 256dpi:object-initializer into d6781fc on manyminds:master.

[256dpi]

Thanks!