Fixed the error handling on the response.

chapter9/listing04/example04.go

@@ -3,8 +3,10 @@ package main
 
 import (
  "encoding/json"
+ "fmt"
  "log"
  "net/http"
+ "strconv"
 )
 
 // main is the entry point for the application.
@@ -30,21 +32,29 @@ func SendJSON(rw http.ResponseWriter, r *http.Request) {
  Email: "[email protected]",
  }
 
- rw.Header().Set("Content-Type", "application/json")
- rw.WriteHeader(200)
-
- if err := json.NewEncoder(rw).Encode(u); err != nil {
- log.Panic(err)
+ data, err := json.Marshal(&u)
+ if err != nil {
+ // We want this error condition to panic so we get a stack trace. This should
+ // never happen. The http package will catch the panic and provide logging
+ // and return a 500 back to the caller.
+ log.Panic("Unable to unmatshal response", err)
  }
 
+ datalen := len(data) + 1 // account for trailing LF
+ h := rw.Header()
+ h.Set("Content-Type", "application/json")
+ h.Set("Content-Length", strconv.Itoa(datalen))
+ rw.WriteHeader(200)
+ fmt.Fprintf(rw, "%s\n", data)
+
  LogResponse(&u)
 }
 
 // LogResponse is used to write the response to the log.
 func LogResponse(v interface{}) {
  d, err := json.MarshalIndent(v, "", " ")
  if err != nil {
- log.Println("Unable to Marshal Response", err)
+ log.Println("Unable to marshal response", err)
  return
  }