联系第 3 方 API 时的错误处理

Question

鉴于我在 Rails 控制器中有以下人为代码：

class ProfilesController < ApplicationController
  def show
    @profile = current_user.profile
    @content_from_third_party_api = @profile.get_that_third_party_content
  end
end

这段代码在views/profiles/show.html.haml：

%h1
  Profile Page!
%h2
  Data from 3rd party:
= @content_from_third_party_api.first.title

这个人为的代码#get_that_third_party_content：

def get_that_third_party_content
  uri = URI.parse("http://api.somesite.com/imfake/")

  http = Net::HTTP.new(uri.host, uri.port)
  request = Net::HTTP::Get.new(uri.request_uri)
  response = http.request(request)

  case response.code.to_i
  when 200 # the happy path
    response
  when (400..499)
    # What should I do/return here?  I have nothing useful to return to the caller.
  when (500..599)
    # Same goes for here...
  end
end

鉴于以下情况，我如何优雅地处理 #get_that_third_party_content 中的超时/错误/等：

• 显示视图期望@content_from_third_party_api 不为零。如果它是 nil，我会在所有地方得到 NilClass 错误
• 显示视图需要渲染一些东西
• 如果出现错误，#get_that_third_party_content 将不返回任何内容
• 感觉我需要做很多 nil 检查......这似乎真的错了
• rescue_from 似乎是一个很好的解决方案，但我不确定这是否很好

Answer 1

您可能希望在这里使用Faraday 之类的东西，因为您可以利用中间件。创建 Faraday 构建器非常简单，您可以编写中间件来处理所有问题。有用于超时（只需要它）和异常处理的本机中间件。

如果您想“优雅地”处理这些用例，中间件对我来说似乎是最合乎逻辑的选择。否则，正如您所指出的，您的控制器中将有复杂的分支逻辑。

# lib/requestor.rb
require 'faraday'
require 'faraday_middleware' # optional, but nice: https://github.com/lostisland/faraday_middleware

# This is just one example. There are literally hundreds of ways to use
# Faraday, and the documentation is quite good.
class APIConnector
  attr_reader :connection

  def initialize(url)
    @connection = Faraday.new(url) do |connection|
      # Set up your connection here (like response and request objects).
      # There are a lot of examples in the Faraday documentation and things
      # really depend on the API you are accessing.
      #
      # You can set things like timeouts, retrys, mashes, rashes, etc.

      # Set some options, such as timeouts
      connection.options[:timeout]      = 10
      connection.options[:open_timeout] = 10
    end
  end

  def get(path)
    connection.get(path)
  end
end

然后在你的控制器中：

class ProfilesController < ApplicationController
  def show
    @profile = current_user.profile
    response = requestor.get('/path')

    if response.success?
      @third_party_content = response.body
    else
      # This changes depending on the volatility of your application. 
      # You might raise an error, show a flash message, kill the 
      # request, etc. It all depends on the context.
      render text: 'API Request failed'
    end
  end

  private

  def requestor
    @requestor ||= Requestor.new(some_url)
  end
end