Question

The model Article has an attribute :rating. This attribute is updated everytime someone rates the article and the average rating is calculated and stored in the database.

Now I want to get the Article with the highes rating. But how?

Answer 1

Either of those two will do the job, depending on which style you prefer:

@article = Article.find(:first, :order => 'rating DESC')

@article = Article.order('rating DESC').first

Edit:

If you already have an array @articles, and you have a good reason why you can’t or shouldn’t run a separate SQL query, you can do something like this:

@top_article = @articles.sort { |a1,a2| a2[:rating] <=> a1[:rating] }.first

Obsolete:

I wonder though, how you can compute the average rating after every new vote, if you only save the average in the database? If the current average rating is 5, and I submit a new rating 10, the number of ratings must be known in order to calculate the new average. How this is done may be relevant for the solution to your problem.