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http.EncodeJSONResponse body writing is not compatible with net/http #1291
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Oops. Seems like a simple PR to fix.
Using this fix myself:
func EncodeJSONResponse(_ context.Context, w http.ResponseWriter, response any) error { w.Header().Set("Content-Type", "application/json; charset=utf-8") if headerer, ok := response.(http.Headerer); ok { for k, values := range headerer.Headers() { for _, v := range values { w.Header().Add(k, v) } } } code := http.StatusOK if sc, ok := response.(http.StatusCoder); ok { code = sc.StatusCode() } w.WriteHeader(code) if !bodyAllowedForStatus(code) { return nil } return json.NewEncoder(w).Encode(response) } // bodyAllowedForStatus reports whether a given response status code // permits a body. See RFC 7230, section 3.3. // forked from net/http/transfer.go func bodyAllowedForStatus(status int) bool { switch { case status >= 100 && status <= 199: return false case status == 204: return false case status == 304: return false } return true }
- added a commit that references this issue
on Apr 13, 2026
What did you do?
http: request method or response status code does not allow bodyIt seems that body is not written only on 204: https://github.com/go-kit/kit/blob/master/transport/http/server.go#L177
However, stdlib defines "no body allowed" as 100-199, 204, 304: https://cs.opensource.google/go/go/+/refs/tags/go1.22.3:src/net/http/transfer.go;l=460
What did you expect?
No error.
What happened instead?
Got an error.