Rails 的“平均”方法不起作用

Question

According to wikibooks.org and rubyonrails.org , this should be working:

Table.average(:score, :conditions => ['user_id=?', 1])

But it's not. Why? When I'm doing above, my console says:

SELECT AVG("table"."score") FROM "table"

No conditions at all.

Eventually, I did what I want like this:

Table.where('user_id=?', 1).average(:score)

But I'm still confused.

Answer 1

You're trying to use so-called finders api which has been deprecated starting from Rails 4.0 and has been moved to a separate gem activerecord-deprecated-finders to ease migration from older versions. Finders api has been completely removed starting from Rails 4.1.

In light of the above your solution

User.where(user_id: 1).average(:score)

is correct.