2009/8/26 Ruby on Rails: Talk <[email protected]>: > > I have the code which creates the following made up of an array of 3 > TreatLists each with a number of Treatlistitems (I've broken it up to > make it easier to read). > > ?> @breakdown > => [ > #<Treatlist:0x23b98ac @items=[ > #<Treatlistitem:0x2389ef4 @longname="Eye Brow Shape", @spend=17.0, > @prodtreat="T", @numsold=2, @unitcost=10.0>]>, > > #<Treatlist:0x235df34 > @items=[#<Treatlistitem:0x235b16c @longname="Back Massage", > @spend=10.0, @prodtreat="T", @numsold=1, @unitcost=10.0>, > #<Treatlistitem:0x23597cc @longname="Hopi Ear Candles", @spend=10.0, > @prodtreat="T", @numsold=1, @unitcost=10.0>, > #<Treatlistitem:0x23582dc @longname="Back Massage (Essential Oils)", > @spend=10.0, @prodtreat="T", @numsold=1, @unitcost=10.0>]>, > > #<Treatlist:0x2357a1c @items=[ > #<Treatlistitem:0x2351b30 @longname="Back Massage", @spend=10.0, > @prodtreat="T", @numsold=1, @unitcost=10.0>, > #<Treatlistitem:0x234f9fc @longname="Hopi Ear Candles", @spend=10.0, > @prodtreat="T", @numsold=1, @unitcost=10.0>, > #<Treatlistitem:0x234cf90 @longname="Eye Brow Shape", @spend=10.0, > @prodtreat="T", @numsold=1, @unitcost=10.0>, > #<Treatlistitem:0x2349db8 @longname="Full Leg Wax DSS", @spend=18.0, > @prodtreat="T", @numsold=2, @unitcost=10.0>, > #<Treatlistitem:0x23476bc @longname="Bridal Make Up", @spend=10.0, > @prodtreat="T", @numsold=1, @unitcost=10.0>, > #<Treatlistitem:0x2342fcc @longname="Collin Face Powder", @spend=10.0, > @prodtreat="P", @numsold=1, @unitcost=10.0>]>] > > I'm trying to add together the 'spend' figures from each but only if > prodtreat = T or P. When I try the following: > >>> @breakdown[1].items.sum{|item| item.spend if item.prodtreat == "T"} > => 30.0 > > it works!!! > > But when I try it with P ... > >>> @breakdown[1].items.sum{|item| item.spend if item.prodtreat == "P"} > > I get the following: > > NoMethodError: You have a nil object when you didn't expect it! > You might have expected an instance of Array. > The error occurred while evaluating nil.+ > from /Library/Ruby/Gems/1.8/gems/activesupport-2.2.2/lib/ > active_support/core_ext/enumerable.rb:63:in `sum' > from (irb):65:in `inject' > from /Library/Ruby/Gems/1.8/gems/activesupport-2.2.2/lib/ > active_support/core_ext/enumerable.rb:63:in `each' > from /Library/Ruby/Gems/1.8/gems/activesupport-2.2.2/lib/ > active_support/core_ext/enumerable.rb:63:in `inject' > from /Library/Ruby/Gems/1.8/gems/activesupport-2.2.2/lib/ > active_support/core_ext/enumerable.rb:63:in `sum' > from /Library/Ruby/Gems/1.8/gems/activesupport-2.2.2/lib/ > active_support/core_ext/enumerable.rb:61:in `sum' > from (irb):65 >>> > > I really have no idea why this is not working or not returning a zero > value?! Any ideas please?
A bit of a guess here but it may be that fact that this will attempt to include some nil values in the sum as the result of the block will be nil (I think) for values that do not match. Perhaps this is ok if the first record is included in the sum but later ones not (so it is performing value + nil) but fails if the first one is not included in the sum (so it performs nil + value). Just a guess. Colin --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Ruby on Rails: Talk" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
