Ruby-on-rails Rails：臭名昭著的“current_user”从何而来？
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Rails: where does the infamous "current_user" come from?
提问by bigpotato
I've been looking around recently into Rails and notice that there are a lot of references to current_user. Does this only come from Devise? and do I have to manually define it myself even if I use Devise? Are there prerequisites to using current_user(like the existence of sessions, users, etc)?
我最近一直在查看 Rails 并注意到有很多对current_user. 这仅来自Devise吗？即使我使用 Devise，我是否必须自己手动定义它？使用是否有先决条件current_user（例如会话、用户等的存在）？
采纳答案by Erik Peterson
It is defined by several gems, e.g. Devise
它由几个 gem 定义，例如 Devise
You'll need to store the user_id somewhere, usually in the session after logging in. It also assumes your app has and needs users, authentication, etc.
您需要将 user_id 存储在某处，通常在登录后的会话中。它还假设您的应用程序拥有并需要用户、身份验证等。
Typically, it's something like:
通常，它类似于：
class ApplicationController < ActionController::Base
def current_user
return unless session[:user_id]
@current_user ||= User.find(session[:user_id])
end
end
This assumes that the User class exists, e.g. #{Rails.root}/app/models/user.rb.
这假设 User 类存在，例如#{Rails.root}/app/models/user.rb.
Updated: avoid additional database queries when there is no current user.
更新：当没有当前用户时避免额外的数据库查询。
回答by Zach Kemp
Yes, current_useruses session. You can do something similar in your application controller if you want to roll your own authentication:
是的，current_user使用session. 如果您想推出自己的身份验证，您可以在应用程序控制器中执行类似的操作：
def current_user
return unless session[:user_id]
@current_user ||= User.find(session[:user_id])
end
