Problems with item NBT

[Melonslise]

Here's a few problems I've ran into.

1. I have a piece of code which checks if a stack has a specific key every tick. However, the NBTTagCompoud#hasKey method seems to be functioning incorrectly. I've debugged it and it looks like it always returns false.

 

public void onUpdate(ItemStack stack, World world, Entity entity, int itemSlot, boolean isSelected)
{
	if(!world.isRemote)
	{
		NBTTagCompound nbt = stack.hasTagCompound() ? stack.getTagCompound() : new NBTTagCompound();	
		System.out.println(nbt.getUniqueId("Identifier"));
		if(!nbt.hasKey("Identifier"))
		{
			nbt.setUniqueId("Identifier", UUID.randomUUID());
			stack.setTagCompound(nbt);
		}
	}
} 

 

2. From what I've heard NBT is handled on the server side only. How would I add a string from an item's NBT to its lore? Trying to retrieve tags on the client side in Item#addInformation always returns null.

3. In what case would I want to use capabilities instead of item NBT?

Edited November 24, 2017 by Melonslise

[Choonster]

8 hours ago, Melonslise said:

1. I have a piece of code which checks if a stack has a specific key every tick. However, the NBTTagCompoud#hasKey method seems to be functioning incorrectly. I've debugged it and it looks like it always returns false.

 

If you look at the implementation of NBTTagCompound#setUniqueId, you'll see that it doesn't use the key you give it directly; it uses two different keys based on it. This means that NBTTagCompound#hasKey will never return true for the key you passed to NBTTagCompound#setUniqueId, you need to use NBTTagCompound#hasUniqueId instead.

 

 

8 hours ago, Melonslise said:

2. From what I've heard NBT is handled on the server side only. How would I add a string from an item's NBT to its lore? Trying to retrieve tags on the client side in Item#addInformation always returns null.

 

ItemStack NBT is automatically synced to the client. If you're setting on the server but can't access it from Item#addInformation, you're doing something wrong. Post your code.

 

 

8 hours ago, Melonslise said:

3. In what case would I want to use capabilities instead of item NBT?

 

To create your own API or implement an existing one like IItemHandler/IFluidHandler; or to store data without having to serialise it to/deserialise it from NBT every time you want to access/modify it.

[Melonslise]

Thanks a lot! For some reason I automatically thought a UUID would be stored just like any other data type. Thanks for clearing things up, everything works now.

Edited November 25, 2017 by Melonslise