Question

Does rails make any guarantees about the order that before filters get executed with either of the following usages:

before_filter [:fn1, :fn2]

or

before_filter :fn1
before_filter :fn2

I’d appreciate any help.

Answer 1

If you refer http://api.rubyonrails.org/v2.3.8/classes/ActionController/Filters/ClassMethods.html, there is a subheading called “Filter chain ordering”, here is the example code from that:

class ShoppingController < ActionController::Base
    before_filter :verify_open_shop

class CheckoutController < ShoppingController
    prepend_before_filter :ensure_items_in_cart, :ensure_items_in_stock

According to the explanation:

The filter chain for the CheckoutController is now
:ensure_items_in_cart, :ensure_items_in_stock,
:verify_open_shop.

So you can explicitly give the order of the filter chain like that.