什么是"env"?机架中间件中的变量? [英] What is the "env" variable in Rack middleware?

问题描述

我知道Rack中间件过滤器是一个带有初始化和调用方法的Ruby类.我知道调用方法需要一个"env"参数.像这样:

I know a Rack middleware filter is a Ruby class with an initialize and a call method. I know the call method takes an "env" argument. Something like this:

class MyFilter
  def initialize(app)
  end

  def call(env)
  end
end

我的问题是:"env"参数发送给"call"的确切含义是什么?这与Rails ENV环境(即开发，测试，生产)是否相同.

My question is: what exactly is the "env" argument sent to "call"? Is this the same as the Rails ENV environment (ie. development, testing, production).

谢谢！

推荐答案

env只是一个哈希.机架本身和各种中间件在其中添加了价值.

env is just a hash. Rack itself and various middlewares add values into it.

要了解哈希中的各种键，请查看 Rack Specification .

To understand what the various keys are in the hash, check out the Rack Specification.

这是一个示例环境散列:

And here is a sample env hash:

{
  "GATEWAY_INTERFACE" => "CGI/1.1",
  "PATH_INFO" => "/index.html",
  "QUERY_STRING" => "",
  "REMOTE_ADDR" => "::1",
  "REMOTE_HOST" => "localhost",
  "REQUEST_METHOD" => "GET",
  "REQUEST_URI" => "http://localhost:3000/index.html",
  "SCRIPT_NAME" => "",
  "SERVER_NAME" => "localhost",
  "SERVER_PORT" => "3000",
  "SERVER_PROTOCOL" => "HTTP/1.1",
  "SERVER_SOFTWARE" => "WEBrick/1.3.1 (Ruby/2.0.0/2013-11-22)",
  "HTTP_HOST" => "localhost:3000",
  "HTTP_USER_AGENT" => "Mozilla/5.0 (Macintosh; Intel Mac OS X 10.9; rv:26.0) Gecko/20100101 Firefox/26.0",
  "HTTP_ACCEPT" => "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
  "HTTP_ACCEPT_LANGUAGE" => "zh-tw,zh;q=0.8,en-us;q=0.5,en;q=0.3",
  "HTTP_ACCEPT_ENCODING" => "gzip, deflate",
  "HTTP_COOKIE" => "jsonrpc.session=3iqp3ydRwFyqjcfO0GT2bzUh.bacc2786c7a81df0d0e950bec8fa1a9b1ba0bb61",
  "HTTP_CONNECTION" => "keep-alive",
  "HTTP_CACHE_CONTROL" => "max-age=0",
  "rack.version" => [1, 2],
  "rack.input" => #<StringIO:0x007fa1bce039f8>,
  "rack.errors" => #<IO:<STDERR>>,
  "rack.multithread" => true,
  "rack.multiprocess" => false,
  "rack.run_once" => false,
  "rack.url_scheme" => "http",
  "HTTP_VERSION" => "HTTP/1.1",
  "REQUEST_PATH" => "/index.html"
}

并使其更易于使用，请检出 Rack :: Request ，这使其更容易访问env哈希值内的值.

And to make it easier to use, checkout Rack::Request which makes it easier to access the values inside the env hash.

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