Fix failed to create second record in same transaction, close #3060

callbacks/transaction.go

@@ -7,7 +7,7 @@ import (
 func BeginTransaction(db *gorm.DB) {
 	if tx := db.Begin(); tx.Error == nil {
 		db.Statement.ConnPool = tx.Statement.ConnPool
-		tx.InstanceSet("gorm:started_transaction", true)
+		db.InstanceSet("gorm:started_transaction", true)
 	} else {
 		tx.Error = nil
 	}

finisher_api.go

@@ -351,7 +351,7 @@ func (db *DB) Transaction(fc func(tx *DB) error, opts ...*sql.TxOptions) (err er
 		}
 	}()
 
-	err = fc(tx.Session(&Session{}))
+	err = fc(tx)
 
 	if err == nil {
 		err = tx.Commit().Error
@@ -364,7 +364,8 @@ func (db *DB) Transaction(fc func(tx *DB) error, opts ...*sql.TxOptions) (err er
 // Begin begins a transaction
 func (db *DB) Begin(opts ...*sql.TxOptions) *DB {
 	var (
-		tx  = db.getInstance()
+		// clone statement
+		tx  = db.Session(&Session{WithConditions: true, Context: db.Statement.Context})
 		opt *sql.TxOptions
 		err error
 	)

statement.go

@@ -351,5 +351,10 @@ func (stmt *Statement) clone() *Statement {
 		newStmt.Joins[k] = j
 	}
 
+	stmt.Settings.Range(func(k, v interface{}) bool {
+		newStmt.Settings.Store(k, v)
+		return true
+	})
+
 	return newStmt
 }

tests/transaction_test.go

@@ -20,6 +20,16 @@ func TestTransaction(t *testing.T) {
 		t.Fatalf("Should find saved record, but got %v", err)
 	}
 
+	user1 := *GetUser("transaction1-1", Config{})
+
+	if err := tx.Save(&user1).Error; err != nil {
+		t.Fatalf("No error should raise, but got %v", err)
+	}
+
+	if err := tx.First(&User{}, "name = ?", user1.Name).Error; err != nil {
+		t.Fatalf("Should find saved record, but got %v", err)
+	}
+
 	if sqlTx, ok := tx.Statement.ConnPool.(gorm.TxCommitter); !ok || sqlTx == nil {
 		t.Fatalf("Should return the underlying sql.Tx")
 	}