[1.16.5] save/transfer of capability

[Luis_ST]

Some time ago I created a capability that expands the enderchest inventory,

now I have encountered the following problem:

if the player dies or uses the end portal, the inventory is deleted.

I know that I have to use the PlayerEvent#Clone to clone the capability

now my questions:

1. Do I need another event in which I have to clone / transfer the capability?
2. how do i clone the capability exactly? that is my beginning with which i tried it:

 

	@SubscribeEvent
	public static void PlayerClone(PlayerEvent.Clone event) {
		
		PlayerEntity original = event.getOriginal();
		PlayerEntity player = event.getPlayer();
		IBackpackItemHandler backpackHandler = original.getCapability(BackpackCapability.BACKPACK, null)
				.orElseThrow(() -> new NullPointerException("The mod Capability<IBackpackItemHandler> is null"));
		IEnderChestItemHandler enderChestHandler = original.getCapability(EnderChestCapability.ENDERCHEST, null)
				.orElseThrow(() -> new NullPointerException("The mod Capability<IBackpackItemHandler> is null"));
		
		player.getCapability(BackpackCapability.BACKPACK, null).orElseGet(() -> backpackHandler);
		player.getCapability(EnderChestCapability.ENDERCHEST, null).orElseGet(() -> enderChestHandler);
		
	}

 

[Draco18s]

47 minutes ago, Luis_ST said:

player.getCapability(BackpackCapability.BACKPACK, null).orElseGet(() -> backpackHandler);

This doesn't actually give the new player entity the capability data. Because orElseGet returns a value (in this case, your local variable, backpackHandler) in the event that the original getCap call returns null. No reference is made between the player object and this handler and as soon as your method returns, the inventory is lost.

 

You need to copy the inventory from one capability to the other.

[Luis_ST]

10 minutes ago, Draco18s said:

This doesn't actually give the new player entity the capability data. Because orElseGet returns a value (in this case, your local variable, backpackHandler) in the event that the original getCap call returns null. No reference is made between the player object and this handler and as soon as your method returns, the inventory is lost.

You need to copy the inventory from one capability to the other.

I've already thought that, but how do I copy the capability from one player to the other since there is no setCapability method?

[Draco18s]

Your capability contains item stacks, right?
Why not move the item stacks from one capability to the other?

[Luis_ST]

34 minutes ago, Draco18s said:

Your capability contains item stacks, right?

yes

 

34 minutes ago, Draco18s said:

Why not move the item stacks from one capability to the other?

like this:

		PlayerEntity original = event.getOriginal();
		PlayerEntity player = event.getPlayer();
		IBackpackItemHandler oldBackpackHandler = original.getCapability(BackpackCapability.BACKPACK, null)
				.orElseThrow(() -> new NullPointerException("The mod Capability<IBackpackItemHandler> is null"));
		CombinedInvWrapper oldEnderChestHandler = original.getCapability(EnderChestCapability.ENDERCHEST, null)
				.orElseThrow(() -> new NullPointerException("The mod Capability<CombinedInvWrapper<IEnderChestItemHandler>> is null"));
		IBackpackItemHandler newBackpackHandler = player.getCapability(BackpackCapability.BACKPACK, null).orElse(null);
		CombinedInvWrapper newEnderChestHandler = player.getCapability(EnderChestCapability.ENDERCHEST, null).orElse(null);
		
		newBackpackHandler = oldBackpackHandler;
		newEnderChestHandler = oldEnderChestHandler;

 

what i don't understand is how to give the new one back to the game?

because somehow I have to tell the game that something has changed

[Draco18s]

"Assign this local variable to the reference stored in this other local variable. Now, recycle these local variables."

 

You haven't actually done anything except create two pointers to the same capability data (which you then feed to the garbage collector).

[Luis_ST]

40 minutes ago, Draco18s said:

"Assign this local variable to the reference stored in this other local variable. Now, recycle these local variables."

You haven't actually done anything except create two pointers to the same capability data (which you then feed to the garbage collector).

I know, but how?

how exactly do I have to hand over my capability? is it enough if I create a new one?

or do I have to replace the capability <IBackpackItemHandler> in my capability class

 

1 hour ago, Luis_ST said:

what i don't understand is how to give the new one back to the game?

because somehow I have to tell the game that something has changed

.

[Draco18s]

Take the items out of one capability and put them into the other.

[Luis_ST]

17 hours ago, Draco18s said:

Take the items out of one capability and put them into the other.

okay i got that, but i'm just too stupid for the rest of it.

which methods do I need to clone the capability?

 

Edit: do I have to create a new capability for the new player and then put the old ones into it?

update: I looked at a few github mods that also use capabilities, from which I created this:

		original.getCapability(BackpackCapability.BACKPACK, null).ifPresent(oldBackpack -> {
			
			player.getCapability(BackpackCapability.BACKPACK, null).ifPresent(newBackpack -> {
				
				newBackpack = oldBackpack;
				
			});
			
		});

 

Edited March 13, 2021 by Luis_ST

[loordgek]

save the old oldBackpack to nbt and load it in the new one

[Luis_ST]

36 minutes ago, loordgek said:

save the old oldBackpack to nbt and load it in the new one

okay i think i can use here serializeNBT and deserializeNBT of the capability provider

right? if so how do I get the provider from my capability?

if not what methods should i use instead?

[Draco18s]

8 hours ago, Luis_ST said:

okay i got that, but i'm just too stupid for the rest of it.

which methods do I need to clone the capability?

 

Edit: do I have to create a new capability for the new player and then put the old ones into it?

update: I looked at a few github mods that also use capabilities, from which I created this:

		original.getCapability(BackpackCapability.BACKPACK, null).ifPresent(oldBackpack -> {
			
			player.getCapability(BackpackCapability.BACKPACK, null).ifPresent(newBackpack -> {
				
				newBackpack = oldBackpack;
				
			});
			
		});

 

Hooray! You did the same thing again! Only this time with lambdas!

 

Lets put it this way, you have a chest on one side of your house with raw beef in it and have just built a new kitchen and you want to move all that beef into a new chest in the kitchen next to a furnace.

 

Which makes more sense?

A) Use pistons to move the old chest to the new chest's location.

B) Take the beef out of the chest and place it in the new chest.

Edited March 13, 2021 by Draco18s

[Luis_ST]

35 minutes ago, diesieben07 said:

You don't have to use NBT.

For all the data you have in your capability, copy it over.

since my capability does not contain a get/set method i have to create it first

do i create this in my provider because it contains the LazyOptional and BackpackItemStackHandler or in the actual capability class?

and in which class does vanilla make this?

since the enderchest inventory and the player invantar are actually only capabilities or that's not true

then I could understand how exactly I clone the capability and could then transfer this to my two capabilities,

which are only one extension of the ItemStackHandler

 

4 minutes ago, Draco18s said:

Which makes more sense?

B😄

[Draco18s]

3 minutes ago, Luis_ST said:

B😄

Then why do you keep building piston contraptions?

[Luis_ST]

14 minutes ago, diesieben07 said:

How do you do anything with your capability then if you can't access its data?

you explained to me how to create a capability (here at the forum)

this is my capability class

 

10 minutes ago, Draco18s said:

Then why do you keep building piston contraptions?

since this was my first approach, and it turned out to be wrong

 

Edited March 13, 2021 by Luis_ST

[Luis_ST]

Just now, diesieben07 said:

Okay so it's just an ItemStackHandler.

yes

 

1 minute ago, diesieben07 said:

Use ItemStackHandler#serializeNBT to write it to NBT then use ItemStackHandler#deserializeNBT to transfer it to the new capability.

because with getCapability I get an extension of IItemHandlerModifiable and no ItemStackHandler can I cast it to ItemStackHandler?

[Luis_ST]

20 minutes ago, diesieben07 said:

Yes you can cast it if you don't intend for other developers to implement your capability.

like that:

		original.getCapability(BackpackCapability.BACKPACK, null).ifPresent(oldBackpack -> {
			
			CompoundNBT nbt = ((ItemStackHandler) oldBackpack).serializeNBT();
					
			player.getCapability(BackpackCapability.BACKPACK, null).ifPresent(newBackpack -> {
				
				((ItemStackHandler) newBackpack).deserializeNBT(nbt);
				
			});
			
		});

 

[loordgek]

yes

[Luis_ST]

32 minutes ago, diesieben07 said:

Use ItemStackHandler#serializeNBT to write it to NBT then use ItemStackHandler#deserializeNBT to transfer it to the new capability.

how do I do that with my extended enderchest inventory the capability contains a CombinedInvWrapper

this is the class of enderchest capability

[Draco18s]

56 minutes ago, Luis_ST said:

since this was my first approach, and it turned out to be wrong

First, second, third, and fourth.

[Luis_ST]

35 minutes ago, diesieben07 said:

You can use the Direction parameter of getCapability. If the direction is not null, return only your handler instead of the combined one.

okay this  is my capability class now

when I try to get the capability on the way:

		original.getCapability(EnderChestCapability.ENDERCHEST, Direction.WEST).ifPresent(oldEnderChest -> {
			
			CompoundNBT nbt = ((ItemStackHandler) oldEnderChest).serializeNBT();
					
			player.getCapability(EnderChestCapability.ENDERCHEST, Direction.WEST).ifPresent(newEnderChest -> {
				
				((ItemStackHandler) newEnderChest).deserializeNBT(nbt);
				
			});
			
		});

 

eclipse gives me the following error:

"Cannot cast from CombinedInvWrapper to ItemStackHandler"

[Luis_ST]

Update: I have changed a few things / tried but in most cases I get a ClassCastException,

because I cannot cast the CombinedInvWrapper to an ItemStackHandler,

although my capability should return an ItemStackHandler if I specify a direction.

 

that is the important part of my capability provider:

		private EnderChestItemStackHandler inventory = new EnderChestItemStackHandler(27);
		private PlayerEntity player;
		private LazyOptional<EnderChestItemStackHandler> lazyOptional = LazyOptional.of(() -> inventory);
		private LazyOptional<CombinedInvWrapper> optional = LazyOptional.of(() -> {
			
			EnderChestInventory enderChestInventory = player.getInventoryEnderChest();
			InvWrapper invWrapper = new InvWrapper(enderChestInventory);
			CombinedInvWrapper combinedInvWrapper = new CombinedInvWrapper(invWrapper, inventory);
			
			return combinedInvWrapper;
			
		});
		
		@Override
		@SuppressWarnings({ "unchecked" })
		public <T> LazyOptional<T> getCapability(Capability<T> cap, Direction side) {
			
			LazyOptional<?> ret = side == null ? optional : lazyOptional;
			return cap == ENDERCHEST && cap != null ? (LazyOptional<T>) ret : LazyOptional.empty();
			
		}

 

and how I am currently trying to get the capability (I have to use IItemHandlerModifiable first because, as already said,

I cannot cast the CombinedInvWrapper to an ItemStackHandler and it should actually work anyway because getCapability should return an extension of the ItemStackHandler in this case)

		original.getCapability(EnderChestCapability.ENDERCHEST, Direction.WEST).ifPresent(oldEnderChest -> {
			
			IItemHandlerModifiable oldItemModifiable = oldEnderChest;
			ItemStackHandler oldItemHandler = (ItemStackHandler) oldItemModifiable;
			CompoundNBT nbt = oldItemHandler.serializeNBT();
					
			player.getCapability(EnderChestCapability.ENDERCHEST, Direction.WEST).ifPresent(newEnderChest -> {
				
				IItemHandlerModifiable newItemModifiable = newEnderChest;
				ItemStackHandler newItemHandler = (ItemStackHandler) newItemModifiable;
				newItemHandler.deserializeNBT(nbt);
				
			});
			
		});

 

what do i have to change?

 

[Draco18s]

1 hour ago, Luis_ST said:

cap == ENDERCHEST && cap != null

if cap IS the enderchest, then it CAN'T be null and vice versa.

 

[Luis_ST]

38 minutes ago, Draco18s said:

if cap IS the enderchest, then it CAN'T be null and vice versa.

1 hour ago, diesieben07 said:

These variable names are terrible.

The code in your Git repository does not use a Direction to query the capability in your PlayerEvent.Clone handler. Please update your Git repo.

updated and changed the things you mentioned

[Luis_ST]

14 hours ago, diesieben07 said:

Here you define that your capability always returns a CombinedInvWrapper. Which is not true now.

okay thanks i changed the capability to IItemHandlerModifiable and now it works

do I have to clone the capability in another event?