英文:
GoLang: Setting header to null for a file:// to http:// request not working
问题
这个问题涉及到在本地静态页面（file://）上使用Web服务器（http://）来提供文件，而不违反CORS。根据这个答案，可以使用一个Web服务器来为本地静态页面提供文件，而不违反CORS。根据这个答案，当从Web服务器发送数据到静态页面时，必须使用一个null的头部。但是下面的两行代码都不起作用，所以我该怎么做呢？
func handler(w http.ResponseWriter, r *http.Request) {
w.Header().Add("Access-Control-Allow-Origin", nil) //这一行
fmt.Fprintf(w, "Hi there, I love %s!", r.URL.Path[1:])
}
func handler(w http.ResponseWriter, r *http.Request) {
w.Header().Add("Access-Control-Allow-Origin", "")
fmt.Fprintf(w, "Hi there, I love %s!", r.URL.Path[1:])
}
第一段代码返回错误信息./main.go:42: cannot use nil as type string in argument to w.Header().Add。
第二段代码可以编译通过，但是在客户端会抛出错误：Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://localhost:8080/aardvark/posts. (Reason: CORS header 'Access-Control-Allow-Origin' missing)。
英文:
This answer about static to static (file:// -> file://) states that a webserver (http://) can be used to serve files to a local static page (file://) without violating CORS. And this answer states that when sending data from a webserver to a static page, a header of null must be used. But neither of the two lines below are working, so how do I do it?
func handler(w http.ResponseWriter, r *http.Request) {
w.Header().Add("Access-Control-Allow-Origin", nil) //this line
fmt.Fprintf(w, "Hi there, I love %s!", r.URL.Path[1:])
}
returns the error ./main.go:42: cannot use nil as type string in argument to w.Header().Add
func handler(w http.ResponseWriter, r *http.Request) {
w.Header().Add("Access-Control-Allow-Origin", "")
fmt.Fprintf(w, "Hi there, I love %s!", r.URL.Path[1:])
}
This compiles but throws the client side error: Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at http://localhost:8080/aardvark/posts. (Reason: CORS header 'Access-Control-Allow-Origin' missing)
答案1
得分: 2
在撰写这个问题之后，我想尝试最后一招，出于绝望，结果奏效了。
func handler(w http.ResponseWriter, r *http.Request) {
w.Header().Add("Access-Control-Allow-Origin", "null")
fmt.Fprintf(w, "Hi there, I love %s!", r.URL.Path[1:])
}
你应该将字符串设置为"null"，而不是空字符串""或nil。
如果你认为这个问题不适合在SO上发布，请留下评论，我会尽快删除它。
英文:
After writing up this question, I thought to try one last thing out of desperation, and it worked.
func handler(w http.ResponseWriter, r *http.Request) {
w.Header().Add("Access-Control-Allow-Origin", "null")
fmt.Fprintf(w, "Hi there, I love %s!", r.URL.Path[1:])
}
You're supposed to set the string to "null", rather than a null string "" or nil
If you don't think this question belongs on SO, please leave a comment and I'll promptly take it down.
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