google-app-engine - CORS 授权 polymer 和 goapp golang

Question

我有与 goapp 服务器交互的 polymer 前端。只要我不在 header 中传递授权 token ，一切都可以正常工作。这是 Polymer 端的代码

<iron-ajax
      auto
        url="http://localhost:8080/ephomenotes"
        handle-as="json"
        last-response="{{response}}"
        headers="[[_computeHeader()]]"
        debounce-duration="300"></iron-ajax>

_computeHeader() {
        var token = localStorage.getItem("savedToken");
         var obj = {};
         obj.Authorization = "Bearer " + token;
         return obj;
        //return {"Authorization": "Bearer " + token};
      }

在golang服务器端

w.Header().Set("Access-Control-Allow-Credentials", "true")
if origin := r.Header.Get("Origin"); origin != "" {
    w.Header().Set("Access-Control-Allow-Origin", origin)
}
w.Header().Set("Access-Control-Allow-Headers", "Accept, Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization")

if r.Method == "OPTIONS" {
    return
}

请注意，我从 polymer 代码中删除了 headers="[[_computeHeader()]]"然后它就可以工作了。但是使用授权 token 时它会抛出以下错误。

XMLHttpRequest cannot load http://localhost:8080/ephomenotes. Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin 'http://localhost:8081' is therefore not allowed access.

请帮忙

Answer 1

解决了这个问题..

为选项创建新路线

r.OPTIONS("/ephomenotes", optionsheader)
r.GET("/ephomenotes", env.EPHomePage)

这是新功能。

func optionsheader(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {

    w.Header().Set("Access-Control-Allow-Credentials", "true")
    if origin := r.Header.Get("Origin"); origin != "" {
        w.Header().Set("Access-Control-Allow-Origin", origin)
    }
    w.Header().Set("Access-Control-Allow-Headers", "Accept, Content-Type, Content-Length, Accept-Encoding, X-CSRF-Token, Authorization")
    // w.Header().Set("Access-Control-Allow-Methods", "POST, GET, OPTIONS, PUT, DELETE")

}

但是我不确定，为什么这个有效？