CODEWITHSUNDEEP
rubyactiverecord
Aditya Mukherji
Aditya Mukherji

Reputation: 9256

ActiveRecord query

I have the following ActiveRecords 

class Product < ActiveRecord::Base  
  has_many :reviews  
end  

class Review < ActiveRecord::Base  
  belongs_to :product  
end

Each review object contains a field named 'rating'
I wish to get a list of all products whose average rating is larger than a specific bound.
I don't understand how to use the find command to do this.
Does find let us do things like that?

Upvotes: 2

Views: 254

Answers (2)

griswoldbar
griswoldbar

Reputation: 499

I'd use SQL when queries start asking for things like conditions on aggregated values as this one does. There are various ways of achieving the result you want - this feels most straightforward to me:

bound = 3
products = Product.where('id in 
  (
    select product_id 
    from reviews 
    group by product_id 
    having avg(rating) > ?)', bound)

Upvotes: 1

RichH
RichH

Reputation: 6138

-Yes, it can do it. Somthing like this should do the trick ...

 Product.find(:all, :include => 'reviews', :conditions => ['review.rating > ?', min_rating])

Edit - Just reread your question. You want to use the average rating. I'd resort to SQL to do this, or if it is a common operation, calculate the average rating and store it in the product every time a rating is saved.

Upvotes: 1

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