API proof of concept: forums#show

[eostrom]

THIS IS NOT A REAL PULL REQUEST AND SHOULD NOT BE MERGED. It's just the easiest way for me to illustrate the approach I'm using so far and ask for feedback. This follows discussion in radar/forem#664.

• route is /api/forums/:id (may be slug)
• versioning is done via Accept header (roughly on the Pat Allan model)
• format is JSON API
• views are built with jbuilder
• authentication is done via session cookies (or whatever the host app is using)

@radar mentioned API keys for authentication, but I don't need them for my app, so I'm keeping it simple.

I'm writing request specs, and not feature or controller specs. It just seems like the natural level for testing this functionality.

I haven't thought about how to represent errors (or read about how JSON API does it). Nor have I started figuring out associations.

I created a separate controller hierarchy, rather than try to cram versioned API functionality into the regular controllers. I am not 100% sure about this.

I am also not sure it wouldn't be better to use JSONAPI::Resources instead of creating the views manually with jbuilder.

[eostrom]

Thanks, I'll make those changes next.

I've just pushed four new commits that contain tentative answers to questions I ran into:

• Can an API user create a Topic without a Post?
• How do we keep /api/ routes from colliding with a forum about APIs?
• How closely should API controllers be integrated with HTML UI controllers?
• How should we represent errors in API responses?

I'm pressing ahead with these tentative answers, but let me know if you have thoughts on them.