我的sessions_controller中的一些数据管理代码有麻烦

Question

a user may belong to several groups.
a user may do a review of each group.
users have been deleted from groups without deleting reviews. this causes errors.
when a user logs in i want to delete user reviews for groups to which they no longer belong. here is the code which isn't working:

@user  = session[:user]
@group = session[:group]
@urevs = UserReview.find(:all, :conditions => ["user_id = ?", @user.id])
unless @urevs.nil?
    @urevs.each do |r|
        ur  = @urevs.id
        @rv = Review.find(:first, :conditions => ["id = ?", @urevs.review_id])
        @gm = GroupMember.find(:first, :conditions => ["group_id = ? and user_id = ?", @rv.group_id, @user.id])
        if @gm.nil?
            @dest = UserReview.find(:first, :conditions => ["id = ?", ur])
            @dest.destroy
        end
    end
end

I would prefer not to do a mysql query to remove all such instances.

Thanks.

Answer 1

@user.user_reviews.destroy_all(["user_reviews.group_id NOT IN (?)", GroupMember.where(:user_id => @user.id).all.map(&:group_id)])

This part can be replaced by a more convenient method @user.groups.map(&:id) if you have such method

GroupMember.where(:user_id => @user.id).all.map(&:group_id)

Also feel free to replace destroy_all with delete_all if you don't need to cleanup after the records.