I want to have a sum of an order by doing something like:
select sum(items.price) from order, items where order.item_id =
items.id
Since Order and Item class are related (using "belongs_to"), I thought
I could use:
Order.sum(''items.price'')
But that doesn''t work as expected... I have to use:
Order.sum(''items.price'', :joins => ''left outer
join items on
items.id=item_id'')
Isn''t ActiveRecord::Calculations supposed to know that I''m
asking for
a join? Why am I supposed to write it?
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> Isn''t ActiveRecord::Calculations supposed to know that I''m asking for > a join? Why am I supposed to write it?sum() wont automatically make the joins for you - it only pulls that data when it''s needed. If you want a sum of all item prices, you do: Item.sum(''price'') If you want a sum of the prices of items within a specific order, you do: order = Order.find(1234) order.items.sum(''price'') You should also be able to do: Order.sum(''items.price'', :include => ''items'') Hope that helps, Steve --~--~---------~--~----~------------~-------~--~----~ 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 rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---
> You should also be able to do: > Order.sum(''items.price'', :include => ''items'')That''s the stuff! Great! Thank you! But "include" it''s not described in the docs for "calculate", only for "count"! I think it should be added to the docs... http://api.rubyonrails.org/classes/ActiveRecord/Calculations/ ClassMethods.html#M000953 --~--~---------~--~----~------------~-------~--~----~ 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 rubyonrails-talk-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org To unsubscribe from this group, send email to rubyonrails-talk-unsubscribe-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org For more options, visit this group at http://groups.google.com/group/rubyonrails-talk?hl=en -~----------~----~----~----~------~----~------~--~---