Add NBT data to an item just picked up in the ItemPickupEvent

[Silvertide]

Is there a way to add data to an item just picked up by a player using the ItemPickupEvent?

I'm currently doing this and it's not working:

ItemStack stack = event.getStack();
Player player = event.getEntity();
CompoundTag nbtData = stack.getOrCreateTag();
if(nbtData.getString("myMod:myTag") == player.getStringUUID()){
	// Do something
} else {
  nbtData.putString("myMod:myTag", player.getStringUUID());
  stack.setTag(nbtData);
}

Every time I pick up the item it doesn't find the tag and tries to set it again. I'm thinking maybe the item either can't be modified or I'm modifying the wrong item and it's already in the players inventory?

Edited April 3, 2023 by Silvertide
clarity

[warjort]

The event.getStack() is just a copy of the items that were picked up so you can see how many were picked up (e.g. if the player didn't have room to pickup the whole stack).

The real items will already be in the player's inventory at this point and might have been merged into another ItemStack of the same items.

See ItemEntity.playerTouch() for the full logic.

[Silvertide]

Ah okay, interesting. I see the hook there for the forge event, yeah it just passes the ItemEntity and Player to the event to check. Do you know of a way to get this functionality? I haven't done a ton with NBT data. I'm not sure where the best place to set this would be. I also noticed there is a Owner attribute already on the ItemEntity. I wonder if that could be used.