Add CommandTag

conn.go

@@ -77,6 +77,20 @@ type Notification struct {
 	Payload string
 }
 
+type CommandTag string
+
+// RowsAffected returns the number of rows affected. If the CommandTag was not
+// for a row affecting command (such as "CREATE TABLE") then it returns 0
+func (ct CommandTag) RowsAffected() int64 {
+	words := strings.SplitN(string(ct), " ", 2)
+	if len(words) != 2 {
+		return 0
+	}
+
+	n, _ := strconv.ParseInt(words[1], 10, 64)
+	return n
+}
+
 // NotSingleRowError is returned when exactly 1 row is expected, but 0 or more than
 // 1 row is returned
 type NotSingleRowError struct {
@@ -760,7 +774,7 @@ func (c *Conn) sendPreparedQuery(ps *preparedStatement, arguments ...interface{}
 // Execute executes sql. sql can be either a prepared statement name or an SQL string.
 // arguments will be sanitized before being interpolated into sql strings. arguments
 // should be referenced positionally from the sql string as $1, $2, etc.
-func (c *Conn) Execute(sql string, arguments ...interface{}) (commandTag string, err error) {
+func (c *Conn) Execute(sql string, arguments ...interface{}) (commandTag CommandTag, err error) {
 	defer func() {
 		if err != nil {
 			c.logger.Error(fmt.Sprintf("Execute `%s` with %v failed: %v", sql, arguments, err))
@@ -781,7 +795,7 @@ func (c *Conn) Execute(sql string, arguments ...interface{}) (commandTag string,
 			case dataRow:
 			case bindComplete:
 			case commandComplete:
-				commandTag = r.ReadCString()
+				commandTag = CommandTag(r.ReadCString())
 			default:
 				if e := c.processContextFreeMsg(t, r); e != nil && err == nil {
 					err = e

conn_pool.go

@@ -223,7 +223,7 @@ func (p *ConnPool) SelectValues(sql string, arguments ...interface{}) (values []
 }
 
 // Execute acquires a connection, delegates the call to that connection, and releases the connection
-func (p *ConnPool) Execute(sql string, arguments ...interface{}) (commandTag string, err error) {
+func (p *ConnPool) Execute(sql string, arguments ...interface{}) (commandTag CommandTag, err error) {
 	var c *Conn
 	if c, err = p.Acquire(); err != nil {
 		return

conn_test.go

@@ -854,3 +854,25 @@ func TestFatalTxError(t *testing.T) {
 		t.Fatal("Connection should not be live but was")
 	}
 }
+
+func TestCommandTag(t *testing.T) {
+	var tests = []struct {
+		commandTag   pgx.CommandTag
+		rowsAffected int64
+	}{
+		{commandTag: "UPDATE 0", rowsAffected: 0},
+		{commandTag: "UPDATE 1", rowsAffected: 1},
+		{commandTag: "DELETE 0", rowsAffected: 0},
+		{commandTag: "DELETE 1", rowsAffected: 1},
+		{commandTag: "CREATE TABLE", rowsAffected: 0},
+		{commandTag: "ALTER TABLE", rowsAffected: 0},
+		{commandTag: "DROP TABLE", rowsAffected: 0},
+	}
+
+	for i, tt := range tests {
+		actual := tt.commandTag.RowsAffected()
+		if tt.rowsAffected != actual {
+			t.Errorf(`%d. "%s" should have affected %d rows but it was %d`, i, tt.commandTag, tt.rowsAffected, actual)
+		}
+	}
+}

helper_test.go

@@ -26,7 +26,7 @@ func mustPrepare(t testing.TB, conn *pgx.Conn, name, sql string) {
 	}
 }
 
-func mustExecute(t testing.TB, conn *pgx.Conn, sql string, arguments ...interface{}) (commandTag string) {
+func mustExecute(t testing.TB, conn *pgx.Conn, sql string, arguments ...interface{}) (commandTag pgx.CommandTag) {
 	var err error
 	if commandTag, err = conn.Execute(sql, arguments...); err != nil {
 		t.Fatalf("Execute unexpectedly failed with %v: %v", sql, err)