Hello!

I'm trying to create a capability that reads a player's CompoundTag, and extracts some custom mod data from it to assemble an object, along with being given one of those mod objects and writing it to a Player's nbt. I've hopefully created the capability correctly, but I'm not sure how to go about having a `Player` read/write this data during a world save, and how I can go about retrieving the data from a given `Player` object on world join (I know I'd need to subscribe to the event, but I have no idea what I'd do from there). Additionally, this code results in "Invalid player data" whenever I join a world, and I don't know what's in here causes that (EDIT: Figured out this was due to my own bad serialization code. Does this mean that the NBT is automatically loaded on world join and saved on world leave?). My full repository can be found here: https://github.com/hammy3502/elementalism , and the relevant code snippets are below:

 

Object with Custom Mod Data (PlayerProgressionData.java):

public class PlayerProgressionData implements INBTSerializable<CompoundTag> {

    public static final String outerTag = "elementalism_data";

    public ProgressionInfo.ElementType type;
    public ProgressionInfo.ElementType type2;
    public List<ProgressionInfo> powersUnlocked;

    public PlayerProgressionData() {
        this.type = ProgressionInfo.ElementType.NONE;
        this.type2 = ProgressionInfo.ElementType.NONE;
        this.powersUnlocked = new ArrayList<>();
    }

    @Override
    public CompoundTag serializeNBT() {
        CompoundTag toRet = new CompoundTag();
        CompoundTag data = new CompoundTag();

        StringBuilder powersList = new StringBuilder();
        for (int i = 0; i < powersUnlocked.size(); i++) {
            powersList.append(powersUnlocked.get(i).id);
            if (i != powersUnlocked.size() - 1) {
                powersList.append(",");
            }
        }
        data.putString("unlockedPowers", powersList.toString());

        data.putString("element1", this.type.id);
        data.putString("element2", this.type2.id);

        toRet.put(outerTag, data);
        return toRet;
    }

    @Override
    public void deserializeNBT(CompoundTag nbt) {
        if (!nbt.contains(outerTag)) return;
        this.powersUnlocked.clear();
        CompoundTag data = nbt.getCompound(outerTag);
        this.type = ProgressionInfo.ElementType.getElementById(data.getString("element1"));
        this.type2 = ProgressionInfo.ElementType.getElementById(data.getString("element2"));

        String[] powerIds = data.getString("unlockedPowers").split(",");
        for (String id : powerIds) {
            ProgressionInfo info = Objects.requireNonNull(ProgressionInfoInit.ALL_PROGRESSION_INFOS.get(id));
            this.powersUnlocked.add(info);
        }


    }
}

Capability Registration (Elementalism.java):

public void registerCapabilities(RegisterCapabilitiesEvent event) {
	event.register(PlayerProgressionData.class);
}

 

Capability Attaching (CommonSubscriber.java):

@SubscribeEvent
    public void attachCapabilities(AttachCapabilitiesEvent<Entity> event) {
        if (!(event.getObject() instanceof Player)) return;

        PlayerProgressionData progressionData = new PlayerProgressionData();
        LazyOptional<PlayerProgressionData> optionalProgressionData = LazyOptional.of(() -> progressionData);
        ICapabilityProvider provider = new ICapabilitySerializable<CompoundTag>() {

            @Override
            public CompoundTag serializeNBT() {
                return progressionData.serializeNBT();
            }

            @Override
            public void deserializeNBT(CompoundTag nbt) {
                progressionData.deserializeNBT(nbt);
            }

            @Nonnull
            @Override
            public <T> LazyOptional<T> getCapability(@Nonnull Capability<T> cap, @Nullable Direction side) {
                if (cap == DATA_STORAGE_CAPABILITY) {
                    return optionalProgressionData.cast();
                }
                return LazyOptional.empty();
            }
        };

        event.addCapability(new ResourceLocation(Elementalism.MOD_ID, "data_storage"), provider);
        event.addListener(optionalProgressionData::invalidate);

    }

 

Thank you so much for any help!

Edited September 21, 20214 yr by hammy3502

Nevermind, I was able to wrap my mind around https://forge.gemwire.uk/wiki/Capabilities#Accessing_a_Capability , and currently have it working!