start using Marshal for creating json responses

cmd/api/healthcheck.go

@@ -1,13 +1,30 @@
 package main
 
 import (
-	"fmt"
+	"encoding/json"
 	"net/http"
 )
 
 func (app *application) healthCheckHandler(w http.ResponseWriter, r *http.Request) {
-	fmt.Fprintln(w, "status: available")
-	fmt.Fprintf(w, "environment: %s\n", app.config.env)
-	fmt.Fprintf(w, "version: %s", version)
+
+	// create a mapping that will be converted to json
+	data := map[string]string{
+		"status":      "available",
+		"environment": app.config.env,
+		"version":     version,
+	}
+
+	js, err := json.Marshal(data)
+	if err != nil {
+		app.logger.Print(err)
+		http.Error(w, "the server encountered an error and could process your request", http.StatusInternalServerError)
+		return
+	}
+
+	js = append(js, '\n')
+
+	w.Header().Set("Content-Type", "application/json")
+
+	w.Write(js)
 
 }

cmd/api/helpers.go

@@ -0,0 +1,20 @@
+package main
+
+import (
+	"errors"
+	"net/http"
+	"strconv"
+
+	"github.com/julienschmidt/httprouter"
+)
+
+func (app *application) readIDParam(r *http.Request) (int64, error) {
+	params := httprouter.ParamsFromContext(r.Context())
+
+	id, err := strconv.ParseInt(params.ByName("id"), 10, 64)
+	if err != nil || id < 1 {
+		return 0, errors.New("invalid id parameter")
+	}
+
+	return id, nil
+}

cmd/api/movies.go

@@ -3,9 +3,6 @@ package main
 import (
 	"fmt"
 	"net/http"
-	"strconv"
-
-	"github.com/julienschmidt/httprouter"
 )
 
 func (app *application) createMovieHandler(w http.ResponseWriter, r *http.Request) {
@@ -13,9 +10,7 @@ func (app *application) createMovieHandler(w http.ResponseWriter, r *http.Reques
 }
 
 func (app *application) showMovieHandler(w http.ResponseWriter, r *http.Request) {
-	params := httprouter.ParamsFromContext(r.Context())
-
-	id, err := strconv.ParseInt(params.ByName("id"), 10, 64)
+	id, err := app.readIDParam(r)
 	if err != nil {
 		http.NotFound(w, r)
 		return