hmmmnnn. for one, you shouldn't be using an instance variable as it does
not need to live outside the scope of the function. that being said,
there is a better way of handling this anyhow.
Make sure that the tables are normalized, it is the best way to allow
rails to figure out all the associations without your help.
I am assuming that the code above is from an activerecord class called
"Customer" where each customer may have many "transactions"?
If this is the case, make sure that your "transactions" table has a
field called "customer_id".
that way you can do this now:
class Customer < ActiveRecord::Base
has_many :transactions
def running_total
#http://www.ruby-doc.org/core/classes/Enumerable.html#M003160
transactions.inject{|m,v| m.amount.to_f + v.amount.to_f}
end
end
class Transaction < ActiveRecord::Base
belongs_to :customer
end
check this link out on associations:
http://api.rubyonrails.org/classes/ActiveRecord/Associations/ClassMethods.html
You can check out what's going on here by using 'script/console' from
within your rails working environment:
a...@aldo-desktop:~/Documents/ruby/stuffses$ script/console
Loading development environment (Rails 2.1.0)
>> customer = Customer.find_by_id(1)
>> customer.transactions #will list all associated transactions
HTH,
Aldo Sarmiento
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