Response header settings is not working for the error case

Question

ctx.Response.Header.Set function is not working for the error case.

Please check the below code,

package main

import "fmt"
import "github.com/valyala/fasthttp"

func main() {
    requestHandler := func(ctx *fasthttp.RequestCtx) {
        ctx.Response.Header.Set("Access-Control-Allow-Origin", "*")
        switch string(ctx.Path()) {
        case "/foo":
            fmt.Fprintf(ctx, "Success result")
        case "/bar":
            ctx.Error("Unsupported path", fasthttp.StatusNotFound)
        }
    }
    fasthttp.ListenAndServe(":8080", requestHandler)
}

The /foo URL's response header is,

Server: fasthttp Date: Mon, 16 Apr 2018 04:05:10 GMT

Content-Type: text/plain; charset=utf-8

Content-Length: 14

Access-Control-Allow-Origin: *

But, the /bar 's response header is,

Server: fasthttp

Date: Mon, 16 Apr 2018 04:05:50 GMT

Content-Type: text/plain; charset=utf-8

Content-Length: 16

Access-Control-Allow-Origin header is not applied. Is anything I missed here?

I'm not familiar with fasthttp nor do I know how a standard implementation should behave but it seems it's what the fasthttp devs [intended](https://github.com/valyala/fasthttp/blob/master/server.go#L895). — mkopriva, Apr 16 '18 at 04:32
@mkopriva great find. fasthttp's document didn't mention anywhere in the document. So, I am not aware of this. Anyway thanks for your reply. — sprabhakaran, Apr 16 '18 at 04:50

score 1 · Answer 1 · answered Nov 02 '20 at 08:18

The method ctx.Error clears the headers intentionally:

// ...
// Warning: this will reset the response headers and body already set!
func (ctx *RequestCtx) Error(msg string, statusCode int) {...}

The solution is to use other methods:

ctx.SetContentType("text/plain")
ctx.SetStatusCode(404)
ctx.SetBodyString("Unsupported path")

Response header settings is not working for the error case

1 Answers1