save should be idempotent #6139 (#6149)

finisher_api.go

@@ -106,7 +106,7 @@ func (db *DB) Save(value interface{}) (tx *DB) {
 		updateTx := tx.callbacks.Update().Execute(tx.Session(&Session{Initialized: true}))
 
 		if updateTx.Error == nil && updateTx.RowsAffected == 0 && !updateTx.DryRun && !selectedUpdate {
-			return tx.Create(value)
+			return tx.Clauses(clause.OnConflict{UpdateAll: true}).Create(value)
 		}
 
 		return updateTx

tests/update_test.go

@@ -610,6 +610,25 @@ func TestUpdateFromSubQuery(t *testing.T) {
 	}
 }
 
+func TestIdempotentSave(t *testing.T) {
+	create := Company{
+		Name: "company_idempotent",
+	}
+	DB.Create(&create)
+
+	var company Company
+	if err := DB.Find(&company, "id = ?", create.ID).Error; err != nil {
+		t.Fatalf("failed to find created company, got err: %v", err)
+	}
+
+	if err := DB.Save(&company).Error; err != nil || company.ID != create.ID {
+		t.Errorf("failed to save company, got err: %v", err)
+	}
+	if err := DB.Save(&company).Error; err != nil || company.ID != create.ID {
+		t.Errorf("failed to save company, got err: %v", err)
+	}
+}
+
 func TestSave(t *testing.T) {
 	user := *GetUser("save", Config{})
 	DB.Create(&user)