I'd like to ask if people have thoughts on clean ways of making behaviour in the model depend on attributes of the request.
Things I'm thinking of:
* per-user Time.zone (currently handled by setting a thread-local variable in the controller)
* created_by and updated_by fields. Googling around, the recommended way seems to be the same, set Thread.current['user'] = session[:user] in a before filter
* updated_ip (i.e. logging request.ip when a model is saved). Ditto.
* when I do a bulk update from a controller, I'd like all the updated_at timestamps to be *exactly* the same (when using millisecond- accurate timestamps), so as to allow the changes to be grouped in a query ("group by updated_at"). That means taking a snapshot of the current time, and using it in all the model updates for the duration of that request.
It seems to me that doing all this via Thread-local variables is a bit icky. For one thing, you have to remember to erase them before each new request. And if you take it to the extreme, you might be tempted to do Thread['session'] = session Thread['request'] = request etc, possibly burying things like access-control logic in the model.
I'd be interested to hear if anyone has implemented a cleaner way for the model layer to make limited callbacks to the controller layer, and how you designed it.
I think you'd want an object which exposes methods that are *not* made public on the controller itself (because you don't want them accessible from the outside world). Thinking aloud:
class FooController < ApplicationController class Callback def initialize(ctrl) @ctrl = ctrl end def time @time ||= Time.now end def zone @zone ||= @ctrl.instance_eval { session[:tz] } end def ip @ip ||= @ctrl.instance_eval { request.ip } end
before do Thread.current['callback'] = Callback.new(self) end end
Any better ideas?
