better error handling

Author: atomotic

db.go

@@ -2,14 +2,15 @@ package main
 
 import (
 	"database/sql"
-	"log"
+
+	"github.com/rs/zerolog/log"
 )
 
 // InitDB create the database table and indexes
 func InitDB(dsn string) *sql.DB {
 	db, err := sql.Open("sqlite3", dsn)
 	if err != nil {
-		log.Fatal("error db")
+		log.Fatal().Msg("database init error")
 	}
 	statement, _ := db.Prepare(`CREATE TABLE IF NOT EXISTS annotations (
 		id INTEGER PRIMARY KEY, 

handlers.go

@@ -38,13 +38,19 @@ func List(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
 
 	rows, err := db.Query("SELECT body FROM annotations where target=?", canvas[0])
 	if err != nil {
-		log.Fatal().Err(err)
+		log.Error().Err(err).Str("action", "list").Msg("db error")
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("500"))
+		return
 	}
 	defer rows.Close()
 	for rows.Next() {
 		err := rows.Scan(&body)
 		if err != nil {
-			log.Fatal().Err(err)
+			log.Error().Err(err).Str("action", "list").Msg("db error")
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Write([]byte("500"))
+			return
 		}
 		list.Resources = append(list.Resources, body)
 	}
@@ -56,30 +62,31 @@ func List(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
 	w.Header().Set("Content-Type", "application/json")
 	enc := json.NewEncoder(w)
 	if err := enc.Encode(list); err != nil {
-		fmt.Println(err)
+		log.Error().Err(err).Str("action", "list").Str("canvas", canvas[0]).Msg("annotation list error")
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("500"))
+		return
 	}
 
 }
 
 // Get retrieve a single annotation with database id
-// TODO: retrieve with annotation id
+// NOTE: just for test, not used by mirador
 func Get(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
 	w.Header().Set("Content-Type", "application/json")
 
 	var body string
-	rows, err := db.Query("SELECT body FROM annotations where id=?", ps.ByName("id"))
+	err := db.QueryRow("SELECT body FROM annotations where id=?", ps.ByName("id")).Scan(&body)
+
 	if err != nil {
-		log.Fatal().Err(err)
-	}
-	defer rows.Close()
-	for rows.Next() {
-		err := rows.Scan(&body)
-		if err != nil {
-			log.Fatal().Err(err)
-		}
-		fmt.Fprintf(w, body)
+		log.Error().Err(err).Str("action", "get").Msg("db error")
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("500"))
+		return
 	}
 
+	w.Header().Set("Content-Type", "application/json")
+	fmt.Fprintf(w, body)
 }
 
 // Delete an annotation
@@ -89,14 +96,20 @@ func Delete(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
 	var anno string
 	err := db.QueryRow("SELECT body FROM annotations where annoid = ?", ps.ByName("id")).Scan(&anno)
 	if err != nil {
-		log.Fatal().Err(err)
+		log.Error().Err(err).Str("action", "delete").Msg("db error")
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("500"))
+		return
 	}
 
 	_, err = db.Exec("DELETE FROM annotations where annoid=?", ps.ByName("id"))
 	if err != nil {
-		log.Fatal().Err(err)
+		log.Error().Err(err).Str("action", "delete").Msg("db error")
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("500"))
+		return
 	}
-	log.Info().Str("annotation-id", ps.ByName("id")).Msg("deleted")
+	log.Info().Str("annotation_id", ps.ByName("id")).Str("action", "delete").Msg("")
 	w.Header().Set("Content-Type", "application/json")
 	fmt.Fprintf(w, anno)
 }
@@ -106,14 +119,18 @@ func Create(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
 	body, err := ioutil.ReadAll(r.Body)
 	defer r.Body.Close()
 	if err != nil {
-		http.Error(w, err.Error(), 500)
+		log.Error().Err(err).Str("action", "create").Msg("")
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("500"))
 		return
 	}
 
 	var annotation Annotation
 	err = json.Unmarshal(body, &annotation)
 	if err != nil {
-		http.Error(w, err.Error(), 500)
+		log.Error().Err(err).Str("action", "create").Msg("")
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("500"))
 		return
 	}
 
@@ -122,7 +139,7 @@ func Create(w http.ResponseWriter, r *http.Request, _ httprouter.Params) {
 	AnnotationWithID, _ := json.Marshal(annotation)
 	statement, _ := db.Prepare("INSERT INTO annotations (annoid, created_at, target, manifest, body) VALUES (?, ?, ?, ?, ?)")
 	statement.Exec(annoid, time.Now(), annotation.Canvas(), annotation.Manifest(), AnnotationWithID)
-	log.Info().Str("annotation-id", annoid).Msg("create")
+	log.Info().Str("annotation_id", annoid).Str("action", "create").Msg("")
 
 	fmt.Fprintf(w, string(AnnotationWithID))
 }
@@ -135,16 +152,21 @@ func Update(w http.ResponseWriter, r *http.Request, ps httprouter.Params) {
 	body, err := ioutil.ReadAll(r.Body)
 	defer r.Body.Close()
 	if err != nil {
-		http.Error(w, err.Error(), 500)
+		log.Error().Err(err).Str("action", "update").Msg("db error")
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("500"))
 		return
 	}
 
 	_, err = db.Exec("UPDATE annotations SET body=? WHERE annoid=?", body, annoid)
 	if err != nil {
-		log.Fatal().Err(err)
+		log.Error().Err(err).Str("action", "update").Msg("db error")
+		w.WriteHeader(http.StatusInternalServerError)
+		w.Write([]byte("500"))
+		return
 	}
 
-	log.Info().Str("annotation-id", annoid).Msg("update")
+	log.Info().Str("annotation_id", annoid).Str("action", "update").Msg("")
 
 	fmt.Fprintf(w, string(body))
 }

main.go

@@ -10,6 +10,7 @@ import (
 	"github.com/julienschmidt/httprouter"
 	_ "github.com/mattn/go-sqlite3"
 	"github.com/mitchellh/go-homedir"
+	"github.com/rs/zerolog"
 	"github.com/rs/zerolog/log"
 	"github.com/zserge/webview"
 )
@@ -26,13 +27,13 @@ func init() {
 }
 
 func main() {
-	log.Logger = log.Output(os.Stdout)
+	log.Logger = log.Output(zerolog.ConsoleWriter{Out: os.Stderr})
 	db = InitDB(annotationsDB)
 	router := httprouter.New()
 
 	ln, err := net.Listen("tcp", "127.0.0.1:0")
 	if err != nil {
-		log.Error().Msg("server err")
+		log.Fatal().Err(err).Msg("server failed to start")
 	}
 	defer ln.Close()
 	go func() {
@@ -49,9 +50,9 @@ func main() {
 			fileServer.ServeHTTP(w, r)
 		})
 
-		log.Info().Msg("# listening on " + ln.Addr().String())
+		log.Info().Str("address", "http://"+ln.Addr().String()).Msg("server started")
 		if err := http.Serve(ln, router); err != nil {
-			log.Fatal().Err(err).Msg("Startup failed")
+			log.Fatal().Err(err).Msg("server failed to start")
 		}
 
 	}()