From 2a716e04e6528f1979dc0a7a2de509f0350e9e04 Mon Sep 17 00:00:00 2001
From: Jinzhu <wosmvp@gmail.com>
Date: Mon, 17 Aug 2020 12:16:42 +0800
Subject: [PATCH] Avoid panic for invalid transaction, close #3271

---
 finisher_api.go           |  6 ++++--
 tests/transaction_test.go | 20 ++++++++++++++++++++
 2 files changed, 24 insertions(+), 2 deletions(-)

diff --git a/finisher_api.go b/finisher_api.go
index 8a3d4199..19534460 100644
--- a/finisher_api.go
+++ b/finisher_api.go
@@ -445,7 +445,7 @@ func (db *DB) Begin(opts ...*sql.TxOptions) *DB {
 
 // Commit commit a transaction
 func (db *DB) Commit() *DB {
-	if committer, ok := db.Statement.ConnPool.(TxCommitter); ok && committer != nil {
+	if committer, ok := db.Statement.ConnPool.(TxCommitter); ok && committer != nil && !reflect.ValueOf(committer).IsNil() {
 		db.AddError(committer.Commit())
 	} else {
 		db.AddError(ErrInvalidTransaction)
@@ -456,7 +456,9 @@ func (db *DB) Commit() *DB {
 // Rollback rollback a transaction
 func (db *DB) Rollback() *DB {
 	if committer, ok := db.Statement.ConnPool.(TxCommitter); ok && committer != nil {
-		db.AddError(committer.Rollback())
+		if !reflect.ValueOf(committer).IsNil() {
+			db.AddError(committer.Rollback())
+		}
 	} else {
 		db.AddError(ErrInvalidTransaction)
 	}
diff --git a/tests/transaction_test.go b/tests/transaction_test.go
index c101388a..aea151d9 100644
--- a/tests/transaction_test.go
+++ b/tests/transaction_test.go
@@ -1,6 +1,7 @@
 package tests_test
 
 import (
+	"context"
 	"errors"
 	"testing"
 
@@ -57,6 +58,25 @@ func TestTransaction(t *testing.T) {
 	}
 }
 
+func TestCancelTransaction(t *testing.T) {
+	ctx := context.Background()
+	ctx, cancelFunc := context.WithCancel(ctx)
+	cancelFunc()
+
+	user := *GetUser("cancel_transaction", Config{})
+	DB.Create(&user)
+
+	err := DB.WithContext(ctx).Transaction(func(tx *gorm.DB) error {
+		var result User
+		tx.First(&result, user.ID)
+		return nil
+	})
+
+	if err == nil {
+		t.Fatalf("Transaction should get error when using cancelled context")
+	}
+}
+
 func TestTransactionWithBlock(t *testing.T) {
 	assertPanic := func(f func()) {
 		defer func() {