i've got a specific problem here and I'm not sure how to handle it. what i need to do is sort a has_many association in a very specific way. class Foo < AR::Base has_many :things end class Thing < AR::Base belongs_to :foo end class Order < Thing end class BInCheck < Thing end class Problem < Thing end class Special < Thing end class CycleCount < Thing end class Notification < AR::Base PRIORITIES = [:order, :bin_check, :problem, :special, :cycle_count] end now, what i need to do when when a foo goes into an 'available' state, i need to create a notification for whatever needs foo next, based on the notification priorities. the problem is the sorting. what i want to do is sort the things for foo according to the Notification::PRIORITIES array. so that all i have to do is pass the first element in to generate the notification. note, that date also plays a part in that if there are 2+ of any type, they are sorted by date (:created_on attribute). one thing i thought of using was an association extension on Foo has_many :things do def for_notification .. end end bug again, i'm still blocked on the sorting. any ideas?
on 2007-03-12 13:40
on 2007-03-12 13:49
Chris Hall wrote: > end > class Special < Thing > now, what i need to do when when a foo goes into an 'available' state, > has_many :things do > def for_notification > .. > end > end > > bug again, i'm still blocked on the sorting. > > > any ideas? How do you decide which priority to pick? I'm assuming that :order is not the one that's always called every time. -- Michael Wang
on 2007-03-12 14:08
yes, that's the priority. per the requirements. when a 'foo' becomes available a notification should be generated based on the following priorities, highest to lowest order, bin check, problem, special, cycle count if there are multiple of a particular type, the oldest gets the notification. so basically what this means if i have say, 3 order, 1 bin check and 1 special associated with foo the oldest order gets the notification if i have 1 bin check and 2 cycle count, the bin check gets the notification. hence why i'd like to sort based on the priorities (and created_on within each) i listed and then just take the first one and generate a priority something like Notification.generate_for foo.things.sorted_for_notifications.first
on 2007-03-12 14:25
Chris Hall wrote: > special associated with foo > > Notification.generate_for foo.things.sorted_for_notifications.first What's the column that's storing the priority in Thing? If you are storing the priority as a string in Thing the simple thing to is to prefix something in the front of the priorities that allows you to sort them easily like: a_order, b_bin_check, etc. or 1_order, 2_bin_check, etc. then you can just do :order => "priority, created_at". If you are storing it as an integer then you just need to make sure that they are ordered properly. E.g. order = 1, bin_check = 2, etc. -- Michael Wang