1 files changed, 28 insertions, 0 deletions
diff --git a/oblast/errors.go b/oblast/errors.go
new file mode 100644
index 0000000..0a58340
--- /dev/null
+++ b/oblast/errors.go
@@ -0,0 +1,28 @@
+// SPDX-FileCopyrightText: 2026 Stefan Majewsky <majewsky@gmx.net>
+// SPDX-License-Identifier: Apache-2.0
+
+package oblast
+
+import (
+	"fmt"
+	"reflect"
+	"strings"
+)
+
+// MissingRecordError is returned by [Store.Update] if one of the rows to be updated does not exist in the DB.
+type MissingRecordError[R any] struct {
+	// The record that was provided to [Store.Update],
+	// but for which no row with the same primary key values could be located.
+	Record R
+	plan   plan
+}
+
+// Error implements the builtin/error interface.
+func (e MissingRecordError[R]) Error() string {
+	keyDescs := make([]string, len(e.plan.PrimaryKeyColumnNames))
+	v := reflect.ValueOf(e.Record)
+	for idx, columnName := range e.plan.PrimaryKeyColumnNames {
+		keyDescs[idx] = fmt.Sprintf("%s = %#v", columnName, v.FieldByIndex(e.plan.IndexByColumnName[columnName]))
+	}
+	return "could not UPDATE record that does not exist in the database: " + strings.Join(keyDescs, ", ")
+}