So previously on 1.16.5 I was using the ItemHandler Capability to read and write the nbt data for the sharetags. But in 1.18.2 Forge doesn't have those methods anymore so I simply copied it in. Obviously, it doesn't work since when I try to get the contents of the itemhandler in my item so that I can render the item on the screen and the stack size, the contained itemstacks don't update until I open the item's inventory. So how can I update the item on the client whenever the itemhandler has changes?

I need to get the inventory in BulletCountRender.java and BulletRadialMenu.java

Item Class: AbstractPouch.java

@Override
    public void readShareTag(ItemStack stack, @Nullable CompoundTag nbt) {
        super.readShareTag(stack, nbt);
        LazyOptional<IItemHandler> optional = AbstractPouch.getData(stack).getOptional();
        if (optional.isPresent()){
            IItemHandler handler = optional.resolve().get();
            if (!(handler instanceof IItemHandlerModifiable))
                throw new RuntimeException("IItemHandler instance does not implement IItemHandlerModifiable");
            IItemHandlerModifiable itemHandlerModifiable = (IItemHandlerModifiable) handler;
            ListTag tagList = nbt.getList("ClientInventory", Tag.TAG_COMPOUND);
            for (int i = 0; i < tagList.size(); i++)
            {
                CompoundTag itemTags = tagList.getCompound(i);
                int j = itemTags.getInt("Slot");

                if (j >= 0 && j < handler.getSlots())
                {
                    itemHandlerModifiable.setStackInSlot(j, ItemStack.of(itemTags));
                }
            }
        }
    }

    @Nullable
    @Override
    public CompoundTag getShareTag(ItemStack stack) {
        LazyOptional<IItemHandler> optional = AbstractPouch.getData(stack).getOptional();
        CompoundTag tag = super.getShareTag(stack);
        if (optional.isPresent()){
            IItemHandler handler = optional.resolve().get();
            ListTag nbtTagList = new ListTag();
            int size = handler.getSlots();
            for (int i = 0; i < size; i++)
            {
                ItemStack stack1 = handler.getStackInSlot(i);
                if (!stack1.isEmpty())
                {
                    CompoundTag itemTag = new CompoundTag();
                    itemTag.putInt("Slot", i);
                    stack1.save(itemTag);
                    nbtTagList.add(itemTag);
                }
            }
            tag.put("ClientInventory", nbtTagList);
        }

        return tag;
    }

Edited March 26, 20232 yr by NindyBun

Right, so I just used a few packets to save the inventory as a Listtag to the item and I just use that instead since nbt data is always synced. It's a very crude way but it works for now.