Added Switch statements to our code

Author: h36yang

src/flows/switch/main.go

@@ -0,0 +1,24 @@
+package main
+
+type httpRequest struct {
+	Method string
+}
+
+func main() {
+	r := httpRequest{Method: "GET"}
+
+	// NOTE: Go has implicit break statements among the cases by default
+	// If we want to case to fall through to the next, use explicit "fallthrough" keyword
+	switch r.Method {
+	case "GET":
+		println("GET request")
+	case "POST":
+		println("POST request")
+	case "PUT":
+		println("PUT request")
+	case "DELETE":
+		println("DELETE request")
+	default:
+		println("Unhandled method")
+	}
+}

src/webservice/controllers/front.go

@@ -1,6 +1,8 @@
 package controllers
 
 import (
+	"encoding/json"
+	"io"
 	"net/http"
 )
 
@@ -11,3 +13,8 @@ func RegisterControllers() {
 	http.Handle("/users", *uc)
 	http.Handle("/users/", *uc)
 }
+
+func encodeResponseAsJSON(data interface{}, w io.Writer) {
+	enc := json.NewEncoder(w)
+	enc.Encode(data)
+}

src/webservice/controllers/user.go

@@ -1,16 +1,127 @@
 package controllers
 
 import (
+	"demo/webservice/models"
+	"encoding/json"
 	"net/http"
 	"regexp"
+	"strconv"
 )
 
 type userController struct {
 	userIDPattern *regexp.Regexp
 }
 
 func (uc userController) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	w.Write([]byte("Hello from the User Controller!"))
+	if r.URL.Path == "/users" || r.URL.Path == "/users/" {
+		switch r.Method {
+		case http.MethodGet:
+			uc.getAll(w)
+		case http.MethodPost:
+			uc.post(w, r)
+		default:
+			w.WriteHeader(http.StatusNotImplemented)
+		}
+	} else {
+		matches := uc.userIDPattern.FindStringSubmatch(r.URL.Path)
+		if len(matches) == 0 {
+			w.WriteHeader(http.StatusBadRequest)
+			w.Write([]byte("Malformed URL"))
+			return
+		}
+
+		id, err := strconv.Atoi(matches[1])
+		if err != nil {
+			w.WriteHeader(http.StatusBadRequest)
+			w.Write([]byte("Malformed User ID"))
+			return
+		}
+
+		switch r.Method {
+		case http.MethodGet:
+			uc.get(id, w)
+		case http.MethodPut:
+			uc.put(id, w, r)
+		case http.MethodDelete:
+			uc.delete(id, w)
+		default:
+			w.WriteHeader(http.StatusNotImplemented)
+		}
+	}
+}
+
+func (uc *userController) getAll(w http.ResponseWriter) {
+	encodeResponseAsJSON(models.GetUsers(), w)
+}
+
+func (uc *userController) get(id int, w http.ResponseWriter) {
+	u, err := models.GetUserByID(id)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return
+	}
+	encodeResponseAsJSON(u, w)
+}
+
+func (uc *userController) post(w http.ResponseWriter, r *http.Request) {
+	u, err := uc.parseRequest(r)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("Could not parse User object"))
+		return
+	}
+
+	u, err = models.AddUser(u)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return
+	}
+	encodeResponseAsJSON(u, w)
+}
+
+func (uc *userController) put(id int, w http.ResponseWriter, r *http.Request) {
+	u, err := uc.parseRequest(r)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("Could not parse User object"))
+		return
+	}
+
+	if u.ID != id {
+		w.WriteHeader(http.StatusBadRequest)
+		w.Write([]byte("ID of submitted user must match ID in URL"))
+		return
+	}
+
+	u, err = models.UpdateUser(u)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return
+	}
+	encodeResponseAsJSON(u, w)
+}
+
+func (uc *userController) delete(id int, w http.ResponseWriter) {
+	err := models.RemoveUserByID(id)
+	if err != nil {
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte(err.Error()))
+		return
+	}
+	w.WriteHeader(http.StatusOK)
+}
+
+func (uc *userController) parseRequest(r *http.Request) (models.User, error) {
+	dec := json.NewDecoder(r.Body)
+	var u models.User
+	err := dec.Decode(&u)
+	if err != nil {
+		return models.User{}, err
+	}
+	return u, nil
 }
 
 // Constructor Function - Go's way of creating constructor as a function

src/webservice/models/user.go

@@ -13,7 +13,7 @@ type User struct {
 }
 
 var (
-	users  []*User
+	users  = []*User{}
 	nextID = 1
 )