Conform closer to database/sql style and add no rows test

conn.go

@@ -85,15 +85,9 @@ func (ct CommandTag) RowsAffected() int64 {
 	return n
 }
 
-// NotSingleRowError is returned when exactly 1 row is expected, but 0 or more than
+var ErrNoRows = errors.New("no rows in result set")
-// 1 row is returned
+var ErrNotificationTimeout = errors.New("notification timeout")
-type NotSingleRowError struct {
+var ErrDeadConn = errors.New("conn is dead")
-	RowCount int64
-}
-
-func (e NotSingleRowError) Error() string {
-	return fmt.Sprintf("Expected to find 1 row exactly, instead found %d", e.RowCount)
-}
 
 type ProtocolError string
 
@@ -101,9 +95,6 @@ func (e ProtocolError) Error() string {
 	return string(e)
 }
 
-var NotificationTimeoutError = errors.New("Notification Timeout")
-var DeadConnError = errors.New("Connection is dead")
-
 // Connect establishes a connection with a PostgreSQL server using config.
 // config.Host must be specified. config.User will default to the OS user name.
 // Other config fields are optional.
@@ -340,7 +331,7 @@ func (c *Conn) Listen(channel string) (err error) {
 }
 
 // WaitForNotification waits for a PostgreSQL notification for up to timeout.
-// If the timeout occurs it returns pgx.NotificationTimeoutError
+// If the timeout occurs it returns pgx.ErrNotificationTimeout
 func (c *Conn) WaitForNotification(timeout time.Duration) (*Notification, error) {
 	if len(c.notifications) > 0 {
 		notification := c.notifications[0]
@@ -370,7 +361,7 @@ func (c *Conn) WaitForNotification(timeout time.Duration) (*Notification, error)
 		if err != nil {
 			c.conn.SetReadDeadline(zeroTime) // we can only return one error and we already have one -- so ignore possiple error from SetReadDeadline
 			if err, ok := err.(*net.OpError); ok && err.Timeout() {
-				return nil, NotificationTimeoutError
+				return nil, ErrNotificationTimeout
 			}
 			return nil, err
 		}
@@ -417,7 +408,7 @@ func (r *Row) Scan(dest ...interface{}) (err error) {
 
 	if !qr.NextRow() {
 		if qr.Err() == nil {
-			return errors.New("No rows")
+			return ErrNoRows
 		} else {
 			return qr.Err()
 		}
@@ -940,7 +931,7 @@ func (c *Conn) processContextFreeMsg(t byte, r *MsgReader) (err error) {
 
 func (c *Conn) rxMsg() (t byte, r *MsgReader, err error) {
 	if !c.alive {
-		return 0, nil, DeadConnError
+		return 0, nil, ErrDeadConn
 	}
 
 	t, err = c.mr.rxMsg()

conn_test.go

@@ -182,6 +182,20 @@ func TestConnectWithMD5Password(t *testing.T) {
 	}
 }
 
+func TestConnectWithConnectionRefused(t *testing.T) {
+	t.Parallel()
+
+	// Presumably nothing is listening on 127.0.0.1:1
+	bad := *defaultConnConfig
+	bad.Host = "127.0.0.1"
+	bad.Port = 1
+
+	_, err := pgx.Connect(bad)
+	if !strings.Contains(err.Error(), "connection refused") {
+		t.Fatal("Unable to establish connection: " + err.Error())
+	}
+}
+
 func TestParseURI(t *testing.T) {
 	t.Parallel()
 
@@ -788,7 +802,7 @@ func TestListenNotify(t *testing.T) {
 
 	// when timeout occurs
 	notification, err = listener.WaitForNotification(time.Millisecond)
-	if err != pgx.NotificationTimeoutError {
+	if err != pgx.ErrNotificationTimeout {
 		t.Errorf("WaitForNotification returned the wrong kind of error: %v", err)
 	}
 	if notification != nil {
@@ -1066,6 +1080,27 @@ func TestQueryRowPreparedErrors(t *testing.T) {
 	}
 }
 
+func TestQueryRowNoResults(t *testing.T) {
+	t.Parallel()
+
+	conn := mustConnect(t, *defaultConnConfig)
+	defer closeConn(t, conn)
+
+	sql := "select 1 where 1=0"
+	psName := "selectNothing"
+	mustPrepare(t, conn, psName, sql)
+
+	for _, sql := range []string{sql, psName} {
+		var n int32
+		err := conn.QueryRow(sql).Scan(&n)
+		if err != pgx.ErrNoRows {
+			t.Errorf("Expected pgx.ErrNoRows, got %v", err)
+		}
+
+		ensureConnValid(t, conn)
+	}
+}
+
 func TestQueryPreparedEncodeError(t *testing.T) {
 	t.Parallel()
 

examples/url_shortener/main.go

@@ -45,11 +45,13 @@ func afterConnect(conn *pgx.Conn) (err error) {
 
 func getUrlHandler(w http.ResponseWriter, req *http.Request) {
 	var url string
-	if err := pool.QueryRow("getUrl", req.URL.Path).Scan(&url); err == nil {
+	err := pool.QueryRow("getUrl", req.URL.Path).Scan(&url)
+	switch err {
+	case nil:
 		http.Redirect(w, req, url, http.StatusSeeOther)
-	} else if _, ok := err.(pgx.NotSingleRowError); ok {
+	case pgx.ErrNoRows:
 		http.NotFound(w, req)
-	} else {
+	default:
 		http.Error(w, "Internal server error", http.StatusInternalServerError)
 	}
 }