It works fine in-game, but when I re-enter the world, all the fields are set to their default values. Its strange because Ive implemented writeNBT and readNBT methods. Also client and server are synchronized, so its not the problem.

Capability code:
 

public class SoulCap {
    public int parryTimer = 0;
    public int CATimer = 0;
    public boolean justParried = false;
    public boolean rightClicked = false;
    public boolean leftClicked = false;
    public double mana = 0;
    public double maxMana = 10;
    public HashMap<String, Integer> usedKeyItems = new HashMap<>();

    public boolean trySpendMana(double a) {
        if (mana >= a){
            mana -= a;
            return true;
        }
        return false;
    }
    public void addMana(double a){
        mana += a;
        if (mana > maxMana)
            mana = maxMana;
    }


    public CompoundNBT getNbt(){
        CompoundNBT tag = new CompoundNBT();
        tag.putInt("parryTimer", parryTimer);
        tag.putInt("CATimer", CATimer);
        tag.putBoolean("justParried", justParried);
        tag.putBoolean("rightClicked", rightClicked);
        tag.putBoolean("leftClicked", leftClicked);
        tag.putDouble("mana", mana);
        tag.putDouble("maxMana", maxMana);
        CompoundNBT keyItems = new CompoundNBT();
        for (String s : usedKeyItems.keySet()){
            keyItems.putInt(s, usedKeyItems.get(s));
        }
        tag.put("usedKeyItems", keyItems);
        return tag;
    }

    public SoulCap setNbt(CompoundNBT nbt){
        parryTimer = nbt.getInt("parryTimer");
        CATimer=  nbt.getInt("CATimer");
        justParried = nbt.getBoolean("justParried");
        rightClicked = nbt.getBoolean("rightClicked");
        leftClicked =  nbt.getBoolean("leftClicked");
        mana = nbt.getDouble("mana");
        maxMana = nbt.getDouble("maxMana");
        CompoundNBT keyItems = nbt.getCompound("usedKeyItems");
        for (String s : keyItems.keySet()){
            usedKeyItems.put(s, keyItems.getInt(s));
        }
        return this;
    }

    public static class SoulProvider implements ICapabilityProvider {
        @CapabilityInject(SoulCap.class)
        public static Capability<SoulCap> SOUL_CAP;
        private final LazyOptional<SoulCap> instance = LazyOptional.of(() -> new SoulCap());

        @Override
        public <T> LazyOptional<T> getCapability(@Nonnull Capability<T> cap, @Nullable Direction side) {
            return cap == SOUL_CAP ? instance.cast() : LazyOptional.empty();
        }

        @Override
        public <T> LazyOptional<T> getCapability(@Nonnull Capability<T> cap) {
            return cap == SOUL_CAP ? instance.cast() : LazyOptional.empty();
        }
    }

    public static class SoulStorage implements Capability.IStorage<SoulCap> {
        @Override
        public INBT writeNBT(Capability<SoulCap> capability, SoulCap soulCap, Direction side) {
            return soulCap.getNbt();
        }

        @Override
        public void readNBT(Capability<SoulCap> capability, SoulCap soulCap, Direction side, INBT nbt) {
            soulCap.setNbt((CompoundNBT)nbt);
        }
    }
}

Registering:
 

@Mod("soul")
@Mod.EventBusSubscriber(bus=Mod.EventBusSubscriber.Bus.MOD)
public class Soul {
	//
	//various stuff
	//
    @SubscribeEvent
    public static void setup(final FMLCommonSetupEvent event) {
        CapabilityManager.INSTANCE.register(SoulCap.class, new SoulCap.SoulStorage(), () -> new SoulCap());
    }
}

Attaching:

@Mod.EventBusSubscriber
public class CapabilityEvents {
    @SubscribeEvent
    static void playerCapability(AttachCapabilitiesEvent<Entity> event){
        if (event.getObject() instanceof PlayerEntity) {
            event.addCapability(new ResourceLocation(Soul.id, "soul"), new SoulCap.SoulProvider());
        }
    }
}

 

Edited June 19, 20214 yr by GrigLog
forgot to remove debug messages

Ive made it like this, but nothing changed:

public static class SoulProvider implements ICapabilitySerializable<INBT> {
        @CapabilityInject(SoulCap.class)
        public static Capability<SoulCap> SOUL_CAP;
        private final LazyOptional<SoulCap> instance = LazyOptional.of(() -> new SoulCap());

        @Override
        public <T> LazyOptional<T> getCapability(@Nonnull Capability<T> cap, @Nullable Direction side) {
            return cap == SOUL_CAP ? instance.cast() : LazyOptional.empty();
        }

        @Override
        public <T> LazyOptional<T> getCapability(@Nonnull Capability<T> cap) {
            return cap == SOUL_CAP ? instance.cast() : LazyOptional.empty();
        }

        @Override
        public INBT serializeNBT() {
            return SOUL_CAP.getStorage().writeNBT(SOUL_CAP, this.instance.resolve().get(), null);
        }

        @Override
        public void deserializeNBT(INBT nbt) {
            SOUL_CAP.getStorage().readNBT(SOUL_CAP, this.instance.resolve().get(), null, nbt);
        }
    }

 

They are called, and they change the SoulProvider.instance and save it to nbt as intended. But looks like the player has some other instance of SoulProvider, which is never (de)serialized. I literally see maxMana=20 in debug and maxMana=10 in game.

Btw I obtain all Capabilities references in code like this:

SoulCap cap = player.getCapability(SoulCap.SoulProvider.SOUL_CAP, null).resolve().get();

mb this one is incorrect?

Yes, this time you were right. But how can I sync server with client now? I dont see any Event of (de)serialization

Or PlayerLoggedIn is fine too?

Looks like it works now, thanks

 

To display it, obviously)