use_ssl 值已更改，但尝试发出 https 请求时会话已开始

Question

我正在使用 Rails 4.2.7 和这段代码来发出 Net::Http 获取请求

    req = Net::HTTP::Get.new(url)
    if !headers.nil?
      headers.each do |k, v|
        req[k] = v
      end
    end
    res = Net::HTTP.new(uri.host, uri.port).start do |http|
      http.use_ssl = (uri.scheme == "https")
      http.request(req)
    end
    status = res.code
    content_type = res['content-type']
    content_encoding = res['content-encoding']
    content = res.body

但是，当我创建一个方案为“https”的方案时，我收到以下错误

Error during processing: use_ssl value changed, but session already started
/Users/davea/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/net/http.rb:758:in `use_ssl='
/Users/davea/Documents/workspace/myproject/app/helpers/webpage_helper.rb:118:in `block in get_content'
/Users/davea/.rvm/rubies/ruby-2.3.0/lib/ruby/2.3.0/net/http.rb:853:in `start'

如何设置 https 同时仍然能够发出我的 GET 请求？

Answer 1

根据文档，use_ssl 必须在开始会话之前设置。

这是我平时的流程：

uri          = URI 'some endpoint with encoded params'
http         = Net::HTTP.new(uri.host, uri.port)
http.use_ssl = true
headers      = headers.each_with_object({}) { |(k, v), hash| hash[k] = v }
http.get(uri.request_uri, initheader = headers)

请参阅get 上的文档。

---

关于你的旁注

if !headers.nil?

如果你只检查是否存在，它会更具可读性：

if headers.present?

甚至更短：

if headers # would return true unless it's nil or false