http.MethodGet lost setLevel

[lxb325710]

func (lvl AtomicLevel) ServeHTTP(w http.ResponseWriter, r *http.Request) {
type errorResponse struct {
Error string json:"error"
}
type payload struct {
Level zapcore.Level json:"level"
}

enc := json.NewEncoder(w)

switch r.Method {
case http.MethodGet:
        lvl.SetLevel(requestedLvl)  //Bug:lost  lvl.SetLevel(requestedLvl)
	enc.Encode(payload{Level: lvl.Level()})
case http.MethodPut:
	requestedLvl, err := decodePutRequest(r.Header.Get("Content-Type"), r)
	if err != nil {
		w.WriteHeader(http.StatusBadRequest)
		enc.Encode(errorResponse{Error: err.Error()})
		return
	}
	lvl.SetLevel(requestedLvl)
	enc.Encode(payload{Level: lvl.Level()})
default:
	w.WriteHeader(http.StatusMethodNotAllowed)
	enc.Encode(errorResponse{
		Error: "Only GET and PUT are supported.",
	})
}

}

[abhinav]

@lxb325710 Can you clarify?

Get should not call setLevel. That should be a read-only operation.

[ozfive]

I agree with @abhinav's comment. The Get operation should not call SetLevel. The Get method should only retrieve the current atomic level and return it as the response payload. The SetLevel operation should only be triggered by a Put request, where the requested level is decoded and passed to the SetLevel function.

In case http.MethodGet: you should just be getting the current level by setting it like so currentLvl := lvl.Level(). The code below is what you want:

func (lvl AtomicLevel) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	type errorResponse struct {
		Error string `json:"error"`
	}
	type payload struct {
		Level zapcore.Level `json:"level"`
	}

	enc := json.NewEncoder(w)

	switch r.Method {
	case http.MethodGet:
		currentLvl := lvl.Level()
		enc.Encode(payload{Level: currentLvl})
	case http.MethodPut:
		requestedLvl, err := decodePutRequest(r.Header.Get("Content-Type"), r)
		if err != nil {
			w.WriteHeader(http.StatusBadRequest)
			enc.Encode(errorResponse{Error: err.Error()})
			return
		}
		lvl.SetLevel(requestedLvl)
		enc.Encode(payload{Level: lvl.Level()})
	default:
		w.WriteHeader(http.StatusMethodNotAllowed)
		enc.Encode(errorResponse{
			Error: "Only GET and PUT are supported.",
		})
	}
}

func decodePutRequest(contentType string, r *http.Request) (zapcore.Level, error) {
	if contentType != "application/json" {
		return zap.InfoLevel, fmt.Errorf("Content-Type must be application/json")
	}
	var payload struct {
		Level string `json:"level"`
	}
	if err := json.NewDecoder(r.Body).Decode(&payload); err != nil {
		return zap.InfoLevel, err
	}
	level, err := zapcore.ParseLevel(payload.Level)
	if err != nil {
		return zap.InfoLevel, err
	}
	return level, nil
}