From 42d190898463ad2b407151ebc05156850fd29591 Mon Sep 17 00:00:00 2001
From: tania <44262898+taniabogatsch@users.noreply.github.com>
Date: Fri, 30 Aug 2024 09:33:05 +0200
Subject: [PATCH] flush before close to obtain a meaningful error message
 before destroying the appender object (#270)

---
 appender.go | 24 ++++++++++++++++++------
 1 file changed, 18 insertions(+), 6 deletions(-)

diff --git a/appender.go b/appender.go
index 0b3d5b77..31396201 100644
--- a/appender.go
+++ b/appender.go
@@ -8,6 +8,7 @@ import "C"
 
 import (
 	"database/sql/driver"
+	"errors"
 	"unsafe"
 )
 
@@ -111,15 +112,26 @@ func (a *Appender) Close() error {
 	a.closed = true
 
 	// Append all remaining chunks.
-	err := a.appendDataChunks()
+	errAppend := a.appendDataChunks()
 
-	// Destroy all appender data.
+	// We flush before closing to get a meaningful error message.
+	var errFlush error
+	state := C.duckdb_appender_flush(a.duckdbAppender)
+	if state == C.DuckDBError {
+		errFlush = duckdbError(C.duckdb_appender_error(a.duckdbAppender))
+	}
+
+	// Destroy all appender data and the appender.
 	destroyTypeSlice(a.ptr, a.types)
-	state := C.duckdb_appender_destroy(&a.duckdbAppender)
+	var errClose error
+	state = C.duckdb_appender_destroy(&a.duckdbAppender)
+	if state == C.DuckDBError {
+		errClose = errAppenderClose
+	}
 
-	if err != nil || state == C.DuckDBError {
-		// We destroyed the appender, so we cannot retrieve the duckdb internal error.
-		return getError(errAppenderClose, invalidatedAppenderError(err))
+	err := errors.Join(errAppend, errFlush, errClose)
+	if err != nil {
+		return getError(invalidatedAppenderError(err), nil)
 	}
 	return nil
 }