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HTTP HEADER

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透過 HTTP HEADER 有很多資訊可以做傳遞

mime_types

MIME(Multipurpose Internet Mail Extensions) 格式

主要用在 HTTP 通訊協定中的請求標頭 Accept 和回應標頭 Content-Type 中，來說明此文件的格式。

Rails 會在 Controller 的 respond_to 方法中辨識並回應所請求的格式樣板，例如瀏覽器請求 application/json 就會回應 json 格式

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Mime::SET.collect(&:to_s)
=> ["text/html",
 "text/plain",
 "text/javascript",
 "text/css",
 "text/calendar",
 "text/csv",
 "text/vcard",
 "image/png",
 "image/jpeg",
 "image/gif",
 "image/bmp",
 "image/tiff",
 "video/mpeg",
 "application/xml",
 "application/rss+xml",
 "application/atom+xml",
 "application/x-yaml",
 "multipart/form-data",
 "application/x-www-form-urlencoded",
 "application/json",
 "application/pdf",
 "application/zip"]

Accept-Language

可以根據瀏覽器的語言，來切換網站的語言

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class ApplicationController < ActionController::Base
  protect_from_forgery with: :exception
  before_action :set_locale

  protected
  def set_locale
    I18n.locale = request.headers['Accept-Language']
  end
end

搭配 http_accept_language gem

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class ApplicationController < ActionController::Base
  protect_from_forgery with: :exception
  before_action :set_locale

  protected
  def set_locale
    locales = I18n.available_locales
    I18n.locale = http_accept_language.compatible_language_from(locales)
  end
end

USING THE ACCEPT HEADER

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#config/routes.rb
require 'api_version'

scope defaults: { format: 'json' } do
  scope module: :v1, constraints: ApiVersion.new('v1') do
    resources :zombies
  end

  scope module: :v2, constraints: ApiVersion.new('v2', true) do
    resources :zombies
  end
end

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#lib/api_version.rb
class ApiVersion
  def initialize(version, default=false)
    @version, @default = version, default
  end

  private
  def check_headers(headers)
    accept = headers['Accept']
  end
  def matches?(request)
    @default || check_headers(request.headers)
    accept && accept.include?("application/vnd.apocalypse.#{@version}+json")
  end
end

application
#payload is application-specific
vnd.apocalypse
#media type is vendor-specific
[.version]
#API version
+json
#response format should be JSON

Token

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#app/models/user.rb
class User < ActiveRecord::Base
  before_create :set_auth_token

  private
  def set_auth_token
    return if auth_token.present?
    self.auth_token = generate_auth_token
  end

  def generate_auth_token
    loop do
      token = SecureRandom.hex
      break token unless self.class.exists?(auth_token: token)
    end
  end
end

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#app/controllers/posts_controller.rb
class EpisodesController < ApplicationController
   before_action :authenticate

   protected
   def authenticate
     authenticate_token || render_unauthorized
   end

   def authenticate_token
     authenticate_with_http_token do |token, options|
       User.find_by(auth_token: token)
     end
   end
end

gem：
http_accept_language

參考文件：
mime types
gem介紹及源碼分析之http_accept_language(四)

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