Rails:在请求范围内共享信息 [英] Rails: share information within a Request scope

问题描述

Rails 中在当前请求范围内共享信息的机制是什么?

What's the mechanism in Rails to share information within the current request scope?

熟悉 Asp.Net 的人会知道有一个 HttpContext 可供在请求期间调用的所有实体使用.

Those familiar with Asp.Net would know there is a HttpContext that is available to all the entities that are invoked during a request.

Rails 中有没有类似的东西?

Anything similar in Rails?

推荐答案

使用 around_filter 和 Thread.current[] 您可以轻松创建请求上下文/范围.请参阅以下示例.

With around_filter and Thread.current[] you can easily create a request context/scope. See the following example.

首先添加您的application_controller.rb:

  around_filter :request_context

  def request_context
    begin
      RequestContext.begin_request
      yield
    ensure
      RequestContext.end_request
    end
  end

现在将以下类添加到 lib/request_context.rb

class RequestContext
  def self.instance
    i = Thread.current[:request_context]
    unless i
      raise "No instance present. In script/rakefiles: use RequestContext.with_scope {}, " +
            "in controller: ensure `around_filter :request_scope` is configured"
    end
    return i
  end

  # Allows the use of this scope from rake/scripts
  # ContextScope.with_scope do |scope|
  #   # do something
  #   ...
  # end
  def self.with_scope
    begin
      begin_request
      yield(instance)
    ensure
      end_request
    end
  end

  def self.begin_request
    raise "request_context already set" if Thread.current[:request_context]
    Thread.current[:request_context] = RequestContext.new
  end

  def self.end_request
    raise "request_context already nil" unless Thread.current[:request_context]
    Thread.current[:request_context] = nil
  end

  # user part, add constructors/getters/setters here

  def initialize
    # you can setup stuff here, be aware that this
    # is being called in _every_ request.
  end
end

这很简单.您可以将数据存储在 RequestContext.instance 对象中，该对象将在每次请求后重新创建.

This is pretty straightforward. You can store data in the RequestContext.instance object, the object will get recreated after every request.

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