customize json response

cmd/api/healthcheck.go

@@ -1,30 +1,23 @@
 package main
 
 import (
-	"encoding/json"
 	"net/http"
 )
 
 func (app *application) healthCheckHandler(w http.ResponseWriter, r *http.Request) {
 
-	// create a mapping that will be converted to json
-	data := map[string]string{
-		"status":      "available",
-		"environment": app.config.env,
-		"version":     version,
+	envelopedHealth := envelope{
+		"status": "available",
+		"system_info": map[string]string{
+			"environment": app.config.env,
+			"version":     version,
+		},
 	}
 
-	js, err := json.Marshal(data)
+	err := app.writeJSON(w, http.StatusOK, envelopedHealth, nil)
 	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

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"encoding/json"
 	"errors"
 	"net/http"
 	"strconv"
@@ -8,6 +9,8 @@ import (
 	"github.com/julienschmidt/httprouter"
 )
 
+type envelope map[string]any
+
 func (app *application) readIDParam(r *http.Request) (int64, error) {
 	params := httprouter.ParamsFromContext(r.Context())
 
@@ -18,3 +21,22 @@ func (app *application) readIDParam(r *http.Request) (int64, error) {
 
 	return id, nil
 }
+
+func (app *application) writeJSON(w http.ResponseWriter, status int, data any, headers http.Header) error {
+	js, err := json.Marshal(data)
+	if err != nil {
+		return err
+	}
+
+	js = append(js, '\n')
+
+	for key, value := range headers {
+		w.Header()[key] = value
+	}
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	w.Write(js)
+
+	return nil
+}

cmd/api/movies.go

@@ -3,6 +3,9 @@ package main
 import (
 	"fmt"
 	"net/http"
+	"time"
+
+	"greenlight.ergz/internal/data"
 )
 
 func (app *application) createMovieHandler(w http.ResponseWriter, r *http.Request) {
@@ -16,5 +19,20 @@ func (app *application) showMovieHandler(w http.ResponseWriter, r *http.Request)
 		return
 	}
 
-	fmt.Fprintf(w, "show the details of movie %d\n", id)
+	movie := data.Movie{
+		ID:        id,
+		CreatedAt: time.Now(),
+		Title:     "Casablanca",
+		Runtime:   102,
+		Genres:    []string{"drama", "romance", "war"},
+		Version:   1,
+	}
+
+	envelopedMovie := envelope{"movie": movie}
+	err = app.writeJSON(w, http.StatusOK, envelopedMovie, nil)
+	if err != nil {
+		app.logger.Print(err)
+		http.Error(w, "the server encountered an error and could process your request", http.StatusInternalServerError)
+	}
+
 }

internal/data/movies.go

@@ -0,0 +1,13 @@
+package data
+
+import "time"
+
+type Movie struct {
+	ID        int64     `json:"id"`
+	CreatedAt time.Time `json:"-"`
+	Title     string    `json:"title"`
+	Year      int32     `json:"year,omitempty"`
+	Runtime   Runtime   `json:"runtime,omitempty,string"`
+	Genres    []string  `json:"gentres,omitempty"`
+	Version   int32     `json:"version"`
+}

internal/data/runtime.go

@@ -0,0 +1,16 @@
+package data
+
+import (
+	"fmt"
+	"strconv"
+)
+
+type Runtime int32
+
+func (r Runtime) MarshalJSON() ([]byte, error) {
+	jsonValue := fmt.Sprintf("%d mins", r)
+
+	quotedJSONValue := strconv.Quote(jsonValue)
+	return []byte(quotedJSONValue), nil
+
+}