ruby-on-rails - 如何在Rails Active Record查找和.map中使用SQL “IN”语句

Question

roles = Role.find_all_by_simulation_id(session[:sim_id])
forum_posts = Post.find(:all, :conditions => ["role_id = ? AND created_at > ?", roles.map(&:id), session[:last_login]])

错误:

SQLite3::SQLException: near ",": syntax error: SELECT * FROM "posts" WHERE (role_id = 1,2,3,4 AND created_at > '2009-05-21 11:54:52') 

Answer 1

改变这个:

forum_posts = Post.find(:all, :conditions => ["role_id = ? AND created_at > ?", roles.map(&:id), session[:last_login]])

至

forum_posts = Post.find(:all, :conditions => ["role_id IN (?) AND created_at > ?", roles.map(&:id), session[:last_login]])