More concise way to write aggregate query


#1

Hi all,

Just curious if anyone knows a cleaner way to write this query…

def payments_for(start_on, end_on)
sum = 0
self.leases.each { |lse|
sum += lse.payments.within(start_on, end_on).sum(:amount)
}
sum
end

Thanks!


#2

On Mar 25, 2009, at 10:46 AM, Neal L wrote:

sum
end

Thanks!

NOTE: This is completely off the top of my head and quite possibly
contains bugs :wink:

has_many :leases do
def payments_for(start_on, end_on)
select_value(“SELECT SUM(payments.amount) FROM payments INNER
JOIN leases ON leases.id = payments.lease_id WHERE
#{proxy_owner.class.send(:sanitize_sql, [‘payments.paid_on BETWEEN ?
AND ? AND leases.some_parent_id = ?’, start_on, end_on,
proxy_owner.id])}”)
end
end

Actually, I realize that I’m thinking of ‘more performant’ rather than
‘cleaner’ by shifting some work to the database. Since I don’t know
where the #within method comes from (named_scope perhaps?), I really
can’t say too much. Your solution is actually quite clean. What
prompted you to ask the question?

-Rob

Rob B. http://agileconsultingllc.com
removed_email_address@domain.invalid


#3

I was reading about symbol to proc and thought there might be a use
here… Yes, within() is a named_scope.

Thanks!

On Mar 25, 10:35 am, Rob B. removed_email_address@domain.invalid