🐕‍🦺 validate body using middleware

README.md

@@ -1,3 +1,6 @@
 # Coffee Shop Microservice
 
-- Built with `Golang`
+## Built with
+
+- [Golang](https://golang.org/) — open source programming language that makes it easy to build simple, reliable, and efficient software
+- [Gorilla](https://www.gorillatoolkit.org/) — The Golang web toolkit

go.mod

@@ -1,3 +1,5 @@
 module github.com/rjNemo/go-micro
 
 go 1.14
+
+require github.com/gorilla/mux v1.7.4

go.sum

@@ -1 +1,2 @@
-golang.org/x/tools v0.0.0-20200713195033-f8240f79c3d3 h1:xV8QVipADSbgfDrrjnUyOJILDkpbFpyoLV4x06POJ7I=
+github.com/gorilla/mux v1.7.4 h1:VuZ8uybHlWmqV03+zRzdwKL4tUnIp1MAQtp1mIFE1bc=
+github.com/gorilla/mux v1.7.4/go.mod h1:DVbg23sWSpFRCP0SfiEN6jmj59UnW/n46BH5rLB71So=

handlers/products.go

@@ -1,12 +1,13 @@
 package handlers
 
 import (
+	"context"
 	"fmt"
 	"log"
 	"net/http"
-	"regexp"
 	"strconv"
 
+	"github.com/gorilla/mux"
 	"github.com/rjNemo/go-micro/products/data"
 )
 
@@ -18,45 +19,8 @@ type Products struct {
 // NewProducts creates a Products handler
 func NewProducts(logger *log.Logger) *Products { return &Products{logger: logger} }
 
-func (p *Products) ServeHTTP(w http.ResponseWriter, r *http.Request) {
-	// get resources
-	if r.Method == http.MethodGet {
-		p.getProducts(w, r)
-		return
-	}
-	// create one resource
-	if r.Method == http.MethodPost {
-		p.addProduct(w, r)
-		return
-	}
-	// update one resource
-	if r.Method == http.MethodPut {
-		// look for ID in the URI using regexp
-		regx := regexp.MustCompile(`/([0-9]+)`)
-		group := regx.FindAllStringSubmatch(r.URL.Path, -1)
-
-		if len(group) != 1 {
-			http.Error(w, "Invalid URI", http.StatusBadRequest)
-			return
-		}
-		if len(group[0]) != 2 {
-			http.Error(w, "Invalid URI", http.StatusBadRequest)
-			return
-		}
-
-		idString := group[0][1]
-		id, _ := strconv.Atoi(idString)
-
-		p.logger.Printf("Got ID: %d", id)
-		p.updateProduct(id, w, r)
-		return
-	}
-	// catch all other HTTP requests
-	w.WriteHeader(http.StatusMethodNotAllowed)
-}
-
-// getProducts writes all products to response in JSON format
-func (p *Products) getProducts(w http.ResponseWriter, r *http.Request) {
+// GetProducts writes all products to response in JSON format
+func (p *Products) GetProducts(w http.ResponseWriter, r *http.Request) {
 	p.logger.Println("Handle 'GET' request")
 	// fetch products from the datastore
 	productList := data.AllProducts()
@@ -69,36 +33,27 @@ func (p *Products) getProducts(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
-// addProduct reads request body and creates new product
-func (p *Products) addProduct(w http.ResponseWriter, r *http.Request) {
+// AddProduct reads request body and creates new product
+func (p *Products) AddProduct(w http.ResponseWriter, r *http.Request) {
 	p.logger.Println("Handle 'POST' request")
-	// create a new product
-	newProd := &data.Product{}
-	// deserialize JSON to product
-	err := newProd.FromJSON(r.Body)
-	if err != nil {
-		errMsg := fmt.Sprintf("Unable to decode data: %s\n", err)
-		http.Error(w, errMsg, http.StatusBadRequest)
-		return
-	}
+	// get product from the request
+	newProd := r.Context().Value(KeyProduct{}).(*data.Product) // cast into a Product
+
 	p.logger.Printf("product: %#v", newProd)
 	data.AddProduct(newProd)
 }
 
-// updateProduct edit product identified by id
-func (p *Products) updateProduct(id int, w http.ResponseWriter, r *http.Request) {
-	p.logger.Println("Handle 'PUT' request")
-	// create a new product
-	newProd := &data.Product{}
-	// deserialize JSON to product
-	err := newProd.FromJSON(r.Body)
-	if err != nil {
-		errMsg := fmt.Sprintf("Unable to decode data: %s\n", err)
-		http.Error(w, errMsg, http.StatusBadRequest)
-		return
-	}
+// UpdateProduct edit product identified by id
+func (p *Products) UpdateProduct(w http.ResponseWriter, r *http.Request) {
+	vars := mux.Vars(r)
+	id, _ := strconv.Atoi(vars["id"])
+
+	p.logger.Println("Handle 'PUT' request", id)
+	// get product from the request
+	newProd := r.Context().Value(KeyProduct{}).(*data.Product) // cast into a Product
+
 	p.logger.Printf("product: %#v", newProd)
-	err = data.UpdateProduct(id, newProd)
+	err := data.UpdateProduct(id, newProd)
 	if err == data.ErrorProductNotFound {
 		http.Error(w, err.Error(), http.StatusNotFound)
 		return
@@ -109,3 +64,27 @@ func (p *Products) updateProduct(id int, w http.ResponseWriter, r *http.Request)
 		return
 	}
 }
+
+// KeyProduct is a key used to pass validated product to handler
+type KeyProduct struct{}
+
+// ProductValidationMiddleware validates the data passed by the user
+func (p *Products) ProductValidationMiddleware(next http.Handler) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// create a new product
+		newProd := &data.Product{}
+		// deserialize JSON to product
+		err := newProd.FromJSON(r.Body)
+		if err != nil {
+			errMsg := fmt.Sprintf("Unable to decode data: %s\n", err)
+			http.Error(w, errMsg, http.StatusBadRequest)
+			return
+		}
+		// add product to the context
+		ctx := context.WithValue(r.Context(), KeyProduct{}, newProd)
+		req := r.WithContext(ctx)
+
+		// call the next handler
+		next.ServeHTTP(w, req)
+	})
+}

main.go

@@ -8,6 +8,7 @@ import (
 	"os/signal"
 	"time"
 
+	"github.com/gorilla/mux"
 	"github.com/rjNemo/go-micro/handlers"
 	"github.com/rjNemo/go-micro/server"
 )
@@ -20,11 +21,21 @@ func main() {
 	// create the handlers
 	productsHandler := handlers.NewProducts(logger)
 	// create a server mux and register the handlers
-	mux := http.NewServeMux()
-	mux.Handle("/", productsHandler)
+	router := mux.NewRouter()
+	// GET
+	getRouter := router.Methods(http.MethodGet).Subrouter()
+	getRouter.HandleFunc("/", productsHandler.GetProducts)
+	// POST
+	postRouter := router.Methods(http.MethodPost).Subrouter()
+	postRouter.HandleFunc("/", productsHandler.AddProduct)
+	postRouter.Use(productsHandler.ProductValidationMiddleware)
+	// PUT
+	putRouter := router.Methods(http.MethodPut).Subrouter()
+	putRouter.HandleFunc("/{id:[0-9]+}", productsHandler.UpdateProduct)
+	putRouter.Use(productsHandler.ProductValidationMiddleware)
 
 	// creates a new server
-	srv := server.New(mux, port)
+	srv := server.New(router, port)
 
 	// non blocking application server
 	go func() {

server/server.go

@@ -6,7 +6,7 @@ import (
 )
 
 // New creates a server using given mux and port
-func New(mux *http.ServeMux, port string) *http.Server {
+func New(mux http.Handler, port string) *http.Server {
 	return &http.Server{
 		Addr:         port,
 		Handler:      mux,