#update_column(s) skips callbacks (which is useful), but it doesn't change the updated_at field on the record by default (which we should be doing in these cases).
This change is made in Spree 2.2 here: b367c629ce
Whatever fee adjustments there are on other line items should be left alone (not recreated), and whatever fee adjustments are already on the order should just be updated.
This method is named "update distribution charge". What this method actually does is delete all of the fee adjustments on an order and all it's line items, then recreate them all from scratch. We call this from lots of different places all the time, and it's incredibly expensive. It even gets called from inside of transactions being run inside callbacks. Renaming it hopefully will add a bit of clarity.
This needs to be a lot more granular!
This method returns the same thing as the Spree::Order#line_items_adjustments scope, but in a slightly less useful format (an array instead of a relation). The method's name is also totally inaccurate, as currently the only adjustments that appear on line items are tax adjustments for inclusive tax rates, which by definition have no effect on the price whatsoever...
We rely now on the exhaustive list of states an order can be in after
checkout. What made this all a bit more messy is that I made up the
"checkout" order state, likely mixing it from the payment model states.
This simplifies things quite a bit and gives meaningful names to things.
Instead of relying on Spree::Order#outstanding_balance we make us of the
result set `balance_value` computed column. So, we ask PostgreSQL to
compute it instead of Ruby and then serialize it from that computed
column. That's a bit faster to compute that way and let's reuse logic.
We hide this new implementation under this features' toggle so it's only
used when enabled. We want hit the old behaviour by default.
:amount is a database field in these cases, as opposed to a method that returns a computed result. Calling `.sum(:amount)` is much more efficient here as it computes the sum at database level, as opposed to `.map(&:amount).sum`, which would fetch and instanciate all the objects first, and then sum the amounts after.
DEPRECATION WARNING: `#deliver` is deprecated and will be removed in Rails 5. Use `#deliver_now` to deliver immediately or `#deliver_later` to deliver through Active Job.
