SQLite3::SQLException: no such column error

I'm trying to sort a Users model by its "likecount" instance method:

@x = Users.all.order(:likecount)

but I keep getting this error:

ActiveRecord::StatementInvalid in UsersController#show
SQLite3::SQLException: no such column: users.likecount: SELECT "users".* FROM "users" ORDER BY "users"."likecount" ASC

What am I doing wrong?