How to sum returned rows from a model using inject?

Here's my current loop:

update_total = model.find(:all)
update_total.each do |row|

  val = ((row.totoff + row.rushoff + row.passoff + row.scoroff +
row.rzonoff + row.fumlost + row.passhint + row.tolost + row.sacksall +
row.tackflossall + row.passeff + row.firdwns + row.thrdwncon +
row.fthdwncon)/14.0).round_to(4)

  row.totals = val
  row.save
  puts "Team = #{row.team.name} and total val = #{val}."
end

This of course looks sloppy. I thought I could use something similar:

val = row.inject(0){|sum,item| sum + item}

.. but I can't figure out how to use this without it adding specific
columns, namely..

team_id, totals, compiled_on, created_at, updated_at

.. these 5 columns should be exempt from sums..

It's not overly important and I can work around it. I guess I just want
to keep my code as clean as possible and didn't know if there is a more
preferred way to sum up a row's totals in rails..

Thanks.

Älphä Blüë wrote:
[...]

.. but I can't figure out how to use this without it adding specific
columns, namely..

team_id, totals, compiled_on, created_at, updated_at

.. these 5 columns should be exempt from sums.

How about using [:column1, :column2, ...] - [:team_id, :totals, ...] ?
Remember, Array#- actually works in Ruby.

Best,

Instead of querying the model for all of this data, I recommend encapsulating this calculation in the model itself. Also, I’d give meaningful names to 14.0 and 4 to clearly communicate what purpose they serve in the calculation.

Then your loop could be:

Model.all.each do |model|

model.recalculate_total

model.save!

puts …

end

Hi Craig,

Did you mean something like this?

Both methods are in the model..

def recalculate_totals(row)
  fields = 5.0
  row.totals = ((row.kickret + row.puntret + row.netpunt +
row.kickretdef + row.puntretdef) / fields).round_to(4)
end

model.compiled_this_week.all.each do |row|
  row.recalculate_totals(row)
  row.save!
  puts "Team = #{row.team.name} and total val = #{row.totals}."
end

Hi,

Yes, and Marnen’s observation in a later message about not needing to pass row is spot on.

Regards,

Craig

Thanks guys.

I changed it to:

def recalculate_totals
  fields = 5.0
  self.totals = ((self.kickret + self.puntret + self.netpunt +
self.kickretdef + self.puntretdef) / fields).round_to(4)
end

and..

model.compiled_this_week.all.each do |row|
  row.recalculate_totals
  row.save!
  puts "Team = #{row.team.name} and total val = #{row.totals}."
end