Fix #17 - panic() after reusing prepared stmt (#18)

driver.go

@@ -47,7 +47,7 @@ type Driver struct{}
 
 const (
 	driverName      string = "vertica-sql-go"
-	driverVersion   string = "0.1.2"
+	driverVersion   string = "0.1.3"
 	protocolVersion uint32 = 0x00030008
 )
 

driver_test.go

@@ -122,7 +122,7 @@ func assertErr(t *testing.T, err error, errorSubstring string) {
 		return
 	}
 
-	t.Fatalf("expected an error, but it was '%s' instead of containing '%s'", errStr, errorSubstring)
+	t.Fatalf("expected an error containing '%s', but found '%s'", errorSubstring, errStr)
 }
 
 func assertNext(t *testing.T, rows *sql.Rows) {
@@ -477,6 +477,38 @@ func TestValueTypes(t *testing.T) {
 	assertNoErr(t, rows.Close())
 }
 
+func TestStmtReuseBug(t *testing.T) {
+	connDB := openConnection(t)
+	defer closeConnection(t, connDB)
+
+	var res bool
+
+	stmt, err := connDB.PrepareContext(ctx, "SELECT true AS res")
+	assertNoErr(t, err)
+
+	// first call
+	rows, err := stmt.QueryContext(ctx)
+	assertNoErr(t, err)
+
+	defer rows.Close()
+
+	assertNext(t, rows)
+	assertNoErr(t, rows.Scan(&res))
+	assertEqual(t, res, true)
+	assertNoNext(t, rows)
+
+	// second call
+	rows, err = stmt.QueryContext(ctx)
+	assertNoErr(t, err)
+
+	defer rows.Close()
+
+	assertNext(t, rows)
+	assertNoErr(t, rows.Scan(&res))
+	assertEqual(t, res, true)
+	assertNoNext(t, rows)
+}
+
 func init() {
 	logger.SetLogLevel(logger.INFO)
 

stmt.go

@@ -67,6 +67,7 @@ type stmt struct {
 	preparedName string
 	parseState   parseState
 	paramTypes   []common.ParameterType
+	lastRowDesc  *msgs.BERowDescMsg
 }
 
 func newStmt(connection *connection, command string) (*stmt, error) {
@@ -176,7 +177,7 @@ func (s *stmt) QueryContextRaw(ctx context.Context, args []driver.NamedValue) (*
 		return s.collectResults()
 	}
 
-	// We aren't a prepared statement, manually interpolate and do as a simpe query.
+	// We aren't a prepared statement, manually interpolate and do as a simple query.
 	cmd, err = s.interpolate(args)
 
 	if err != nil {
@@ -196,9 +197,12 @@ func (s *stmt) QueryContextRaw(ctx context.Context, args []driver.NamedValue) (*
 
 		switch msg := bMsg.(type) {
 		case *msgs.BEDataRowMsg:
+			if rows == emptyRowSet {
+				rows = newRows(s.lastRowDesc, s.conn.serverTZOffset)
+			}
 			rows.addRow(msg)
 		case *msgs.BERowDescMsg:
-			rows = newRows(msg, s.conn.serverTZOffset)
+			s.lastRowDesc = msg
 		case *msgs.BECmdCompleteMsg:
 			break
 		case *msgs.BEErrorMsg:
@@ -341,9 +345,12 @@ func (s *stmt) collectResults() (*rows, error) {
 
 		switch msg := bMsg.(type) {
 		case *msgs.BEDataRowMsg:
+			if rows == emptyRowSet {
+				rows = newRows(s.lastRowDesc, s.conn.serverTZOffset)
+			}
 			rows.addRow(msg)
 		case *msgs.BERowDescMsg:
-			rows = newRows(msg, s.conn.serverTZOffset)
+			s.lastRowDesc = msg
 		case *msgs.BEErrorMsg:
 			return emptyRowSet, msg.ToErrorType()
 		case *msgs.BEEmptyQueryResponseMsg: