I have attached an inventory to an item with the slot size of one (At the beggining the slot is empty).

When you right click with this item a gold ingot will be set in the slot.

If you sneak and right click the Display name of the inserted item will be printed. (At first "Air" because not item is set)

 

The issue was already adressed here, but there was never as solution.

Old issue

public class InventoryTestItem extends Item {
    public InventoryTestItem(Properties properties) {
        super(properties);
        setRegistryName("inv_test");
    }

    @Override
    public ActionResult<ItemStack> onItemRightClick(World worldIn, PlayerEntity playerIn, Hand handIn) {
        if(playerIn.isSneaking()) {
            playerIn.getHeldItem(handIn).getCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY,null).ifPresent((h)-> {
                ItemStackHandler handler = (ItemStackHandler) h;
                handler.setStackInSlot(0,new ItemStack(Items.GOLD_INGOT));
            });
        }else {
            playerIn.getHeldItem(handIn).getCapability(CapabilityItemHandler.ITEM_HANDLER_CAPABILITY,null).ifPresent((h)-> {
                ItemStackHandler handler = (ItemStackHandler) h;
                System.out.println(handler.getStackInSlot(0).getDisplayName());
            });
        }
        return super.onItemRightClick(worldIn, playerIn, handIn);
    }

    @Nullable
    @Override
    public ICapabilityProvider initCapabilities(ItemStack stack, @Nullable CompoundNBT nbt) {
        return new InventoryTestProvider();
    }

    public class InventoryTestProvider implements ICapabilityProvider, ICapabilitySerializable<CompoundNBT> {

        public ItemStackHandler handler;

        public InventoryTestProvider() {
            this.handler = new ItemStackHandler(1);
        }

        @Nonnull
        @Override
        public <T> LazyOptional<T> getCapability(@Nonnull Capability<T> capability, @Nullable Direction side) {
            if(capability == CapabilityItemHandler.ITEM_HANDLER_CAPABILITY) {
                return LazyOptional.of(()->(T)handler);
            }
            return LazyOptional.empty();
        }

        @Override
        public CompoundNBT serializeNBT() {
            CompoundNBT tag = new CompoundNBT();
            tag.put("itemHandler",handler.serializeNBT());
            return tag;
        }

        @Override
        public void deserializeNBT(CompoundNBT nbt) {
            handler.deserializeNBT(nbt.getCompound("itemHandler"));
        }
    }
}

 

The ItemStack will always keep the Gold Ingot (if set), even when moved in inventories (like chests).

But when I move the Item in the Creative Inventory (for example from slot 1 to 2) the capability is reset and the "Air" is printed as Displayname.

Edited January 13, 20205 yr by MrMarnic

I'm not sure that this can be fixed. The client has authoratative control over their inventory when in creative mode (that's literally how it works, the client says "yeah, this slot is X now"). As such moving an item from one slot to another has the effect of destroying and recreating the stack (pickup: "this slot is now air", place: "this slot is now a backpack"). Unless the client knew about the capability (and its data), then the capability gets reset (and even then, the client would have to know to send that cap data to the server).

Edited January 13, 20205 yr by Draco18s

3 minutes ago, Draco18s said:

I'm not sure that this can be fixed. The client has authoratative control over their inventory when in creative mode (that's literally how it works, the client says "yeah, this slot is X now"). As such moving an item from one slot to another has the effect of destroying and recreating the stack (pickup: "this slot is now air", place: "this slot is now a backpack"). Unless the client knew about the capability (and its data), then the capability gets reset (and even then, the client would have to know to send that cap data to the server).

Ok I undestand that. But can I maybe send the capability trough getShareTag() ? Or is this not possible at all and I can not create a Backpack item with capabilites?

Thank you very much. It is working now with getShareTag and readShareTag.