滑轨。请求的资源上不存在“ Access-Control-Allow-Origin”标头

Question

错误：所请求的资源上没有“ Access-Control-Allow-Origin”标头。

Backund Ruby on Rails，前端为Angular 5。

application.rb

...
module Dkeeper
  class Application < Rails::Application
    config.middleware.use Rack::Cors do
      allow do
      origins '*'
      resource '*', headers: :any, methods: [:get, :post, :put, :patch, :delete, :options, :head]
    end
end
...

Answer 1

根据docs

，您好像丢失了insert_before 0。

config.middleware.insert_before 0, Rack::Cors do
  allow do
    origins '*'
    resource '*', headers: :any, methods: [:get, :post, :options]
  end
end