Updates based on #30

Allocate []bytes for reading data in and write out indented JSON.

Author: Edward Muller

server.go

@@ -1,9 +1,11 @@
 package main
 
 import (
+	"bytes"
 	"encoding/json"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"log"
 	"net/http"
 	"os"
@@ -29,48 +31,46 @@ func handleComments(w http.ResponseWriter, r *http.Request) {
 	// Stat the file, so we can find it's current permissions
 	fi, err := os.Stat(dataFile)
 	if err != nil {
-		http.Error(w, fmt.Sprintf("Unable to stat data file (%s): %s", dataFile, err), http.StatusInternalServerError)
+		http.Error(w, fmt.Sprintf("Unable to stat the data file (%s): %s", dataFile, err), http.StatusInternalServerError)
 		return
 	}
 
-	// Open the file Read/Write
-	cFile, err := os.OpenFile(dataFile, os.O_RDWR, fi.Mode())
+	// Read the comments from the file.
+	commentData, err := ioutil.ReadFile(dataFile)
 	if err != nil {
-		http.Error(w, fmt.Sprintf("Unable to open data file (%s): %s", dataFile, err), http.StatusInternalServerError)
+		http.Error(w, fmt.Sprintf("Unable to read the data file (%s): %s", dataFile, err), http.StatusInternalServerError)
 		return
 	}
-	defer cFile.Close() //Ensure the file is closed when we are done.
 
 	switch r.Method {
 	case "POST":
 		// Decode the JSON data
 		comments := make([]comment, 0)
-		commentsDecoder := json.NewDecoder(cFile)
-		if err := commentsDecoder.Decode(&comments); err != nil {
-			http.Error(w, fmt.Sprintf("Unable to read comments from data file (%s): %s", dataFile, err), http.StatusInternalServerError)
+		if err := json.Unmarshal(commentData, &comments); err != nil {
+			http.Error(w, fmt.Sprintf("Unable to Unmarshal comments from data file (%s): %s", dataFile, err), http.StatusInternalServerError)
 			return
 		}
 
 		// Add a new comment to the in memory slice of comments
 		comments = append(comments, comment{Author: r.FormValue("author"), Text: r.FormValue("text")})
 
-		// Truncate the file and Seek to the beginning of it
-		if err := cFile.Truncate(0); err != nil {
-			http.Error(w, fmt.Sprintf("Unable to truncate data file (%s): %s", dataFile, err), http.StatusInternalServerError)
+		// Marshal the comments to indented json.
+		commentData, err = json.MarshalIndent(comments, "", "    ")
+		if err != nil {
+			http.Error(w, fmt.Sprintf("Unable to marshal comments to json: %s", err), http.StatusInternalServerError)
 			return
 		}
-		if r, err := cFile.Seek(0, 0); r != 0 && err != nil {
-			http.Error(w, fmt.Sprintf("Unable to seek to beginning of data file (%s): %s", dataFile, err), http.StatusInternalServerError)
+
+		// Write out the comments to the file, preserving permissions
+		err := ioutil.WriteFile(dataFile, commentData, fi.Mode())
+		if err != nil {
+			http.Error(w, fmt.Sprintf("Unable to write comments to data file (%s): %s", dataFile, err), http.StatusInternalServerError)
 			return
 		}
 
-		// Write out the json response
-		commentsEncoder := json.NewEncoder(cFile)
-		commentsEncoder.Encode(comments)
-
 	case "GET":
 		// stream the contents of the file to the response
-		io.Copy(w, cFile)
+		io.Copy(w, bytes.NewReader(commentData))
 
 	default:
 		// Don't know the method, so error