Railscasts - Performing Calculations on Models

#14

Apr 04, 2007

Performing Calculations on Models

Did you know ActiveRecord provides class methods for performing calculations on models? You can even use these methods through associations.

Tags: active-record

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Task.sum(:priority)
Task.sum(:priority, :conditions => 'complete=0')
Task.maximum(:priority)
Task.minimum(:priority)
Task.average(:priority)
p = Project.find(:first)
p.tasks.sum(:priority)
p.tasks.sum(:priority, :conditions => 'complete=0')

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3 comments

1. santosh Aug 01, 2007 at 01:59

This is very use ful for new programmers who doing their projects in ROR...
So keep sending comments and what u nw ,u should share with ur thoughts with others and would be better for improving our knowledge....So Keep sending wt u know ..and learn wt u wt u dont no by this format........
And one more thing i want to tel u is please send some material on ROR to my mail.......
OK Thanks,
Santosh

2. omfg Aug 02, 2007 at 13:33

Hey, you forgot to put your email here so I can send you some info on "ROR".

3. Joe Grossberg Aug 07, 2007 at 08:40

Next railscast: how to leave comments that don't make you look like a semi-literate teenager.

4. Matt Grande Apr 14, 2008 at 15:57

What's that funky thing showing your SQL in the background?

5. roller8 Apr 28, 2008 at 22:26

@Matt: I think you're referring to "tailing the development log". It's a technique for watching what's getting written to the log in real time.

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Very good tutorial..Thank you, Ryan.

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how to leave comments that don't make you look like a semi-literate teenager.

21. Dolce & Gabbana Belts Sep 01, 2010 at 22:54

I think this is a great post. One thing that I find the most helpful is number five. Sometimes when I write, I just let the flow of the words and information come out so much that I loose the purpose. It’s only after editing when I realize what I’ve done. There’s defiantly a lot of great tips here I’m going to try to be more aware of.

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