# How to add up an array's element with a rails way?

**URL:** <https://www.ruby-forum.com/t/how-to-add-up-an-arrays-element-with-a-rails-way/169558>\
**Category:** Rails\
**Created:** [June 5, 2009, 9:17am UTC](https://www.ruby-forum.com/t/how-to-add-up-an-arrays-element-with-a-rails-way/169558 "2009-06-05T09:17:28Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Kevin\_Fu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/a6a055/32.png) [@Kevin\_Fu](https://www.ruby-forum.com/u/Kevin_Fu)\
**Post date:** [June 5, 2009, 9:17am UTC](https://www.ruby-forum.com/t/how-to-add-up-an-arrays-element-with-a-rails-way/169558/1 "2009-06-05T09:17:28Z")

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Hi,

I have a method like this, calculating the sub\_total in an order model:

def sub\_total  
result = 0  
for item in self.order\_items  
result += item.price  
end  
result  
end

Is there a rails way to make the method more simple and concise?

Thank you 🙂

–  
regards,  
Kai Fu

Material Science and Engineering  
Huazhong University of Science and Technology  
Wuhan Hubei Province P.R.China  
E-mail: removed\_email\_address@domain.invalid

---

<div class="post-metadata">

**Author:** ![Kevin\_Fu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/a6a055/32.png) [@Kevin\_Fu](https://www.ruby-forum.com/u/Kevin_Fu)\
**Post date:** [June 5, 2009, 9:21am UTC](https://www.ruby-forum.com/t/how-to-add-up-an-arrays-element-with-a-rails-way/169558/2 "2009-06-05T09:21:00Z")

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On Jun 5, 5:01 am, Kevin Fu [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> end
> 
> Is there a rails way to make the method more simple and concise?

Have a peak at the sum method 🙂

Fred

---

<div class="post-metadata">

**Author:** ![Kevin\_Fu](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/k/a6a055/32.png) [@Kevin\_Fu](https://www.ruby-forum.com/u/Kevin_Fu)\
**Post date:** [June 5, 2009, 9:53am UTC](https://www.ruby-forum.com/t/how-to-add-up-an-arrays-element-with-a-rails-way/169558/3 "2009-06-05T09:53:19Z")

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use active record sum method

self.order\_items.sum( :price )

-Sandip

On Fri, Jun 5, 2009 at 12:50 PM, Frederick C. \<  
removed\_email\_address@domain.invalid\> wrote:

> > for item in self.order\_items  
> > Fred

–  
Ruby on Rails Developer

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