Thanks dan, I'll use this one for now.. We're still a pretty small, internal, few-records shop.
On Sep 28, 4:42 pm, Dan Manges <[EMAIL PROTECTED]> wrote: > Hi Dave, > > You can use methods from the Enumerable module to get a list of > salaries and calculate the sum. Try something like this: > > def subscriber_salaries > subscribers.map(&:salary).sum > end > > That will loop over each subscriber, build an array of the salaries, > and then calculate the sum. I would use this approach unless due to > the size of the data set you want to bring back the result directly > from the database. > > Hope this helps, > > Danhttp://www.dcmanges.com/blog > > On Sep 28, 4:14 pm, dschruth <[EMAIL PROTECTED]> wrote: > > > Hey Dan, > > > Got another question about this. > > > What if salary is not really a column in the database? > > > What if it's a variable which is just a function of two other database > > columns? > > > For example what if 'salary' is a variable defined in the Magazine > > object but it's either 'gross_income' or 'gross_pay' (depending on > > which is selected via a third column's value) ? > > > When I try to use the non-column *variable* salary below, i get the > > following error: > > > "PGError: ERROR: column "salary" does not exist" > > > Basically I'm just asking how to sum up related objects' variables. > > (which are not stored in the database) > > > On Sep 22, 1:14 pm, Dan Manges <[EMAIL PROTECTED]> wrote: > > > > On Sep 22, 1:41 pm, dschruth <[EMAIL PROTECTED]> wrote: > > > > > Lets just use your Magazine / Subscriber example for now. > > > > > I want to do something like this: > > > > -------------------------------------------------------- > > > > class Magazine > > > > def subscriber_salaries > > > > Subscriber.calculate(:sum, :salary, :conditions => "magazine_id = > > > > " + id.to_s) # PGError: ERROR: column "magazine_id" does not > > > > exist > > > > end > > > > end > > > > You need to implement subscriber_salaries like this: > > > > class Magazine > > > has_many :subscriptions > > > has_many :subscribers, :through => :subscriptions > > > def subscriber_salaries > > > subscribers.calculate(:sum, :salary) > > > end > > > end > > > > -Dan --~--~---------~--~----~------------~-------~--~----~ 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 -~----------~----~----~----~------~----~------~--~---
