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#3557 ✓stale
Greg Hazel

count(:id, :distinct => true) as default

Reported by Greg Hazel | December 10th, 2009 @ 02:03 AM

When joining with other tables, it is often wrong to use .count() to get the number of records. For example when trying to count the number of users who have posts:

User.scoped(:joins => :posts).count

Gives a count of all the posts, since it's counting rows returned by the DB. However, the query was built on User, so one would expect the count to be related to the number of Users. For example these are equivalent:

User.scoped(:joins => :posts).count
Post.scoped(:joins => :user).count

This query does the right thing, which is counting the number of users who have posts:

User.scoped(:joins => :posts).count(:id, :distinct => true)

So, it seems like .count() should maybe default to using "(:id, :distinct => true)", with the option to say :distinct => false, etc, instead of the other way around.

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