ragserver: fix other variants to be similar to ragserver-genkit

Apply suggestions from go.dev/cl/608737 to the other ragserver variants

Change-Id: I627cec1ff21c8f7c1b1d257b542435793ade680d
Reviewed-on: https://go-review.googlesource.com/c/example/+/609305
TryBot-Bypass: Eli Bendersky <eliben@google.com>
Auto-Submit: Eli Bendersky <eliben@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Reviewed-by: Eli Bendersky <eliben@google.com>

Author: eliben

ragserver/ragserver-langchaingo/json.go

@@ -14,7 +14,7 @@ import (
 // readRequestJSON expects req to have a JSON content type with a body that
 // contains a JSON-encoded value complying with the underlying type of target.
 // It populates target, or returns an error.
-func readRequestJSON(target any, req *http.Request) error {
+func readRequestJSON(req *http.Request, target any) error {
 	contentType := req.Header.Get("Content-Type")
 	mediaType, _, err := mime.ParseMediaType(contentType)
 	if err != nil {
@@ -26,14 +26,11 @@ func readRequestJSON(target any, req *http.Request) error {
 
 	dec := json.NewDecoder(req.Body)
 	dec.DisallowUnknownFields()
-	if err := dec.Decode(target); err != nil {
-		return err
-	}
-	return nil
+	return dec.Decode(target)
 }
 
 // renderJSON renders 'v' as JSON and writes it as a response into w.
-func renderJSON(w http.ResponseWriter, v interface{}) {
+func renderJSON(w http.ResponseWriter, v any) {
 	js, err := json.Marshal(v)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)

ragserver/ragserver-langchaingo/main.go

@@ -60,7 +60,7 @@ func main() {
 
 	mux := http.NewServeMux()
 	mux.HandleFunc("POST /add/", server.addDocumentsHandler)
-	mux.HandleFunc("GET /query/", server.queryHandler)
+	mux.HandleFunc("POST /query/", server.queryHandler)
 
 	port := cmp.Or(os.Getenv("SERVERPORT"), "9020")
 	address := "localhost:" + port
@@ -84,7 +84,7 @@ func (rs *ragServer) addDocumentsHandler(w http.ResponseWriter, req *http.Reques
 	}
 	ar := &addRequest{}
 
-	err := readRequestJSON(ar, req)
+	err := readRequestJSON(req, ar)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		return
@@ -108,7 +108,7 @@ func (rs *ragServer) queryHandler(w http.ResponseWriter, req *http.Request) {
 		Content string
 	}
 	qr := &queryRequest{}
-	err := readRequestJSON(qr, req)
+	err := readRequestJSON(req, qr)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		return

ragserver/ragserver/json.go

@@ -14,7 +14,7 @@ import (
 // readRequestJSON expects req to have a JSON content type with a body that
 // contains a JSON-encoded value complying with the underlying type of target.
 // It populates target, or returns an error.
-func readRequestJSON(target any, req *http.Request) error {
+func readRequestJSON(req *http.Request, target any) error {
 	contentType := req.Header.Get("Content-Type")
 	mediaType, _, err := mime.ParseMediaType(contentType)
 	if err != nil {
@@ -26,14 +26,11 @@ func readRequestJSON(target any, req *http.Request) error {
 
 	dec := json.NewDecoder(req.Body)
 	dec.DisallowUnknownFields()
-	if err := dec.Decode(target); err != nil {
-		return err
-	}
-	return nil
+	return dec.Decode(target)
 }
 
 // renderJSON renders 'v' as JSON and writes it as a response into w.
-func renderJSON(w http.ResponseWriter, v interface{}) {
+func renderJSON(w http.ResponseWriter, v any) {
 	js, err := json.Marshal(v)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)

ragserver/ragserver/main.go

@@ -52,7 +52,7 @@ func main() {
 
 	mux := http.NewServeMux()
 	mux.HandleFunc("POST /add/", server.addDocumentsHandler)
-	mux.HandleFunc("GET /query/", server.queryHandler)
+	mux.HandleFunc("POST /query/", server.queryHandler)
 
 	port := cmp.Or(os.Getenv("SERVERPORT"), "9020")
 	address := "localhost:" + port
@@ -77,7 +77,7 @@ func (rs *ragServer) addDocumentsHandler(w http.ResponseWriter, req *http.Reques
 	}
 	ar := &addRequest{}
 
-	err := readRequestJSON(ar, req)
+	err := readRequestJSON(req, ar)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		return
@@ -127,7 +127,7 @@ func (rs *ragServer) queryHandler(w http.ResponseWriter, req *http.Request) {
 		Content string
 	}
 	qr := &queryRequest{}
-	err := readRequestJSON(qr, req)
+	err := readRequestJSON(req, qr)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		return