Unity - How to save and load lists (Binary Saving and Loading)

Question

I'm trying to figure out how you would save & load list of data. I've gotten my code to work with single data but unsure of how a list one would work. I have a Character class so that means I can have multiple characters and I would like to save each of those character's hp, mana etc.

//SaveManager class that I can call from anywhere to save and load
public static class SaveManager 
{
    //SAVE
    public static void Save(Character c)
    {
        BinaryFormatter formatter = new BinaryFormatter();
        string path = Application.persistentDataPath + "/Save.save";
        FileStream stream = new FileStream(path, FileMode.Create);

        PartyData data = new PartyData(c);

        formatter.Serialize(stream, data);
        stream.Close();
    }

    //LOAD
    public static PartyData Load()
    {
        string path = Application.persistentDataPath + "/Save.save";
        if (File.Exists(path))
        {
            BinaryFormatter formatter = new BinaryFormatter();
            FileStream stream = new FileStream(path, FileMode.Open);

            PartyData data = formatter.Deserialize(stream) as PartyData;
            stream.Close();

            return data;
        }
        else
        {
            Debug.Log("Save FIle not Found");
            return null;
        }
    }

}

PartyData class is what I'm using to save the Character data to.

[System.Serializable]
public class PartyData
{
    public int hp;

    public PartyData(Character cParty)
    {
        hp = cParty.HP;       
    }
}

Character class that contains stats etc

public class Character
{
   public int HP { get; set; }

   public int Mana { get; set; }
}

And then finally I have the CharacterParty class that I attach to a gameobject, this class contains multiple characters and calls the Save and Load functions:

public class CharacterParty : MonoBehaviour
{
    [SerializeField] List<Character> characters;

    public List<Character> Characters
    {
        get
        {
            return characters;
        }
    }

    public void SaveParty()
    {
        SaveManager.SaveMC(characters[0]);
    }
    public void LoadParty()
    {
        PartyData data = SaveManager.LoadMC();

        characters[0].HP = data.hp;

    }
}

Now for testing purposes I tried saving & loading just the character's hp at index 0 and it works but now I wanna save a list of multiple character's hp and mana etc. I just don't know how the list would work with serialization saving and loading. My code probably needs a little bit of change to get the list working so I hope someone can help me out with an example.

Answer 1

Use JsonUtility class - this is Unity's built-in utility for JSON.

Also with this you can serialize any class without [System.Serializable]

Save:

// Parties list
List<PartyData> parties = new List<PartyData>();

// Add your parties here
// First argument is an instance of a class or any other object
// If second argument set to true, it makes JSON more human-readable
string json = JsonUtility.ToJson(parties, false);

// .. saving the file

Load:

// .. loading the file

// First argument is the JSON
List<PartyData> parties = JsonUtility.FromJson<List<PartyData>>(json);

// .. do stuff with the list

EDIT:

If you really want to use BinaryFormatter, then this is for saving:

List<PartyData> parties = new List<PartyData>();
// .. add parties
formatter.Serialize(stream, parties)

For loading:

List<PartyData> parties = formatter.Deserialize(stream) as List<PartyData>;
// .. do stuff

SECOND EDIT:

This one should work. You would do something like that:

// Save class
[Serializable]
public class Save
{
    public List<PartyData> parties;
    // .. add other stuff here
}

// For loading
try
{
    // Deserializing the save
    Save save = (Save)formatter.Deserialize(stream);
    // .. do stuff with other data if you added some
    foreach (PartyData data in save.parties)
    {
        // .. do stuff with data
    }
}
catch (Exception e)
{
    // .. can you just acnowledge... E
    // Oopsie! An error occured. The save file is probably COWWUPTED
    Debug.LogWarning($"An error occured while loading the file: {e}");
}

// For saving
List<PartyData> parties = new List<PartyData>();
// .. add parties by calling parties.Add(party_here);
// Creating a save
Save save = new Save();
// Adding parties to save
save.parties = parties;
// Serialize to a file
formatter.Serialize(stream, parties);