Avoid N+1 queries: add default_scope to Refinery::Page to include :translations

[LouisStAmour]

Installed Bullet and besides a few bugs of my own, one of the first things it began complaining about was some of the Refinery::Page.by_slug lookups I was doing, since they'd generate a query followed by a second query for the translation lookup from Globalize.

While I was able to resolve this sometimes, it proved nearly impossible when looking up .children to also do the include. In fact, the extra query seemed to happen every time I looked up a page.

So I found an answer on StackOverflow I figured I'd report this as a pull request. I don't expect this to get automatically merged, as I haven't the time to consider any implications of this. But it works for my project as follows, in a decorator:

Refinery::Page.class_eval do
  default_scope { includes(:translations) }
end

[parndt]

CI is now failing for pages.

As a rule, I'm pretty uncomfortable with default_scope.. couldn't we just add the includes(:translations) to the APIs that are issuing too many queries?

[LouisStAmour]

Given the StackOverflow report, it appears to be part of the magic that is Globalize, so it's quite possible this is an upstream bug. Those infinite redirects in the failing tests look painful, so let's hold off until I can take a second look I guess. :)

[bricesanchez]

This hotfix :

Refinery::Page.class_eval do
  default_scope { includes(:translations, :children) }
end

helps me to avoid the warning of bullet but not the load time, which stay to ~24.00s for 30 pages.

I'm still facing a performance problem on dev : #2950