snapshot of https://github.com/ent/ent.git (master, 2026-09-15; blobs > 131072B omitted)

examples/version/example_test.go

@@ -0,0 +1,55 @@
+// Copyright 2019-present Facebook Inc. All rights reserved.
+// This source code is licensed under the Apache 2.0 license found
+// in the LICENSE file in the root directory of this source tree.
+
+package main
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"time"
+
+	"entgo.io/ent/examples/version/ent"
+	_ "entgo.io/ent/examples/version/ent/runtime"
+	"entgo.io/ent/examples/version/ent/user"
+
+	_ "github.com/mattn/go-sqlite3"
+)
+
+func Example_optimisticLock() {
+	client, err := ent.Open("sqlite3", "file:ent?mode=memory&cache=shared&_fk=1")
+	if err != nil {
+		log.Fatalf("failed opening connection to sqlite: %v", err)
+	}
+	defer client.Close()
+	ctx := context.Background()
+	// Run the auto migration tool.
+	if err := client.Schema.Create(ctx); err != nil {
+		log.Fatalf("failed creating schema resources: %v", err)
+	}
+
+	usr := client.User.Create().SetStatus(user.StatusOnline).SaveX(ctx)
+	fmt.Println(usr.ID, usr.Status)
+
+	usrCopy := client.User.Query().OnlyX(ctx)
+	affected := client.User.Update().
+		Where(user.ID(usrCopy.ID), user.Version(usrCopy.Version)).
+		SetStatus(user.StatusOffline).
+		SetVersion(time.Now().UnixNano()).
+		SaveX(ctx)
+	fmt.Println(affected)
+
+	// The operation won't updated the database because the user was updated by another process (usrCopy).
+	affected = client.User.Update().
+		Where(user.ID(usr.ID), user.Version(usr.Version)).
+		SetStatus(user.StatusOffline).
+		SetVersion(time.Now().UnixNano()).
+		SaveX(ctx)
+	fmt.Println(affected)
+
+	// Output:
+	// 1 online
+	// 1
+	// 0
+}