Serialization

🧩 1️⃣ Brief definition

Serialization is the process of converting an object (object) in a program

→ into data that can be stored or transmitted (string, file, byte, JSON, v.v.)

And vice versa, Deserialization is the process of converting that data back into an object.

💬 Simple wording:

Serialization = “Package an object into data that can be saved or sent.”

Deserialization = “Unpack that data back into an object for reuse.”

🧱 2️⃣ Real-world example

Serialization is like taking a snapshot of a game character → saving it to a file .save.
Deserialization is when the game loads that file again → the character appears exactly as before (level, item, HP...).

🧠 3️⃣ In programming, why do we need serialization?

Situation Purpose 💾 Store data (Save/Load) Write object to a file JSON, Binary, XML, v.v. 🌐 Transmit data over the network Send object from client → server (or vice versa). ☁️ API / Database / Cloud Convert object into JSON to REST API process. 🧩 Unity Editor Unity serializes data to display & save in the scene. 🧠 Cache or config file Temporarily store configuration or gameplay data.

⚙️ 4️⃣ How it works

Example with C#:

[System.Serializable]
public class PlayerData {
    public string name;
    public int level;
    public float hp;
}

➕ Serialize (Save as JSON)

PlayerData player = new PlayerData { name = "Na", level = 5, hp = 99.5f };
string json = JsonUtility.ToJson(player);
Debug.Log(json);

Result:

{"name":"Na","level":5,"hp":99.5}

🔄 Deserialize (Read the object again)

PlayerData loaded = JsonUtility.FromJson<PlayerData>(json);
Debug.Log(loaded.name); // "Na"

➡️ From JSON → back into an object PlayerData that can be used in code.

🧰 5️⃣ Serialization in Unity

Unity serializes all data in a scene, prefab, or ScriptableObject to:

Save values in Editor.
Display in Inspector.
Save to a file .unity, .prefab, .asset when you click Save.

🧩 Unity can only serialize:

---

🔧 Unity example

[System.Serializable]
public class InventoryItem {
    public string itemName;
    public int amount;
}

public class PlayerInventory : MonoBehaviour {
    [SerializeField] private List<InventoryItem> items; // hiển thị & lưu trong Inspector
}

→ Unity will serialize this list into the scene or prefab file,

so when you reload the scene, the data stays exactly the same.

🧠 6️⃣ How many common serialization types are there?

Type Description Example JSON Serialization Text form, easy to read, most common {"name":"Na","hp":100} Binary Serialization Faster, smaller, harder to read Used for files .save or .dat XML Serialization Text form with tags <Player><Name>Na</Name></Player> Custom Serialization Self-defined read/write logic Used in Unity Editor Tools

💾 7️⃣ Real example – Game Save System (Unity)

Save game:

void SaveGame(PlayerData data) {
    string json = JsonUtility.ToJson(data);
    File.WriteAllText(Application.persistentDataPath + "/save.json", json);
}

Load game:

PlayerData LoadGame() {
    string json = File.ReadAllText(Application.persistentDataPath + "/save.json");
    return JsonUtility.FromJson<PlayerData>(json);
}

➡️ Automatically save all player information → read it back when the game starts.