[1.11.2] Items with Inventories: Persistence (Solved)

[BotanicNitro]

After banging my head into a wall for a few days, I've come here to ask for some assistance in a project of mine. Up-to-date documentation and best practices are often difficult to find, so please correct me if I've made terrible blunders in my code - especially if I'm terribly over-complicating things.

 

My main goals:
1. Create an item that contains data and an inventory.
2. Create a GUI that allows a user to swap items and see data.
3. Persist instance data while the given ItemStack exists.

 

My approach so far:
1. Create a custom Capability (impl, storage, provider) implementing IInventory.
2. Use initCapabilities to return my custom provider.
3. Trigger player.openGui() on item right click.

 

My issue(s) with this approach:
1. The inventory will wipe itself occasionally during play, and consistently upon reloading the world.
2. Bizarrely, the numeric data persists correctly.

 

Additional questions:
- As I understand it, IInventory is deprecated. Is there a better way to meet my goals without it?

 

Notes:
- The issue seems potentially related to my storage of slots in an NBTTagList. The first minimum-impl I was going to submit used a raw ItemStack for internal storage and a lone NBTTagCompound for serialization, and did not exhibit the noted issues. My actual implementation is much like the one now present.

 

Linked is a minimum implementation that exhibits these issues.

 

Main Class
Capability
Capability: Impl
Capability: Provider
Capability: Storage
Example Container
Example GuiContainer
Example GuiHandler
Example Item

 

2017-07-01 11:45

Capability (2)

Capability: Impl (2)

Capability: Provider (2)

Capability: Storage (2)

Edited July 1, 2017 by BotanicNitro
Change title

[Choonster]

You should be using IItemHandler, Forge's replacement for IInventory. You can use or extend ItemStackHandler, the standard IItemHandler implementation.

 

ItemStackHandler implements INBTSerializable, you should use those methods to read it from/write it to NBT. Alternatively, use the IItemHandler capability's IStorage instance.

 

I'm not sure exactly why your code isn't working, but I noticed that you're comparing the ItemStack to ItemStack.EMPTY directly; don't do this. Use ItemStack#isEmpty to check if an ItemStack is empty, ItemStack.EMPTY is just one possible empty ItemStack.

[BotanicNitro]

7 hours ago, Choonster said:

You should be using IItemHandler, Forge's replacement for IInventory. You can use or extend ItemStackHandler, the standard IItemHandler implementation.

 

ItemStackHandler implements INBTSerializable, you should use those methods to read it from/write it to NBT. Alternatively, use the IItemHandler capability's IStorage instance.

 

I'm not sure exactly why your code isn't working, but I noticed that you're comparing the ItemStack to ItemStack.EMPTY directly; don't do this. Use ItemStack#isEmpty to check if an ItemStack is empty, ItemStack.EMPTY is just one possible empty ItemStack.

 

1. I initially started out extending IItemHandler to manage my inventory, but Slot wants an instance of a class that extends IInventory. How would I get a GUI working with IItemHandler? I would prefer not to extend ItemStackHandler, as I wish to store other data that will be related to this inventory, but I'm not too stubborn to consider it if it becomes the only viable option.
2. My own inventory serialization code works extremely similarly to IItemHandler's. However, I use an array instead of a list. I will do further testing to see if following more closely with that structure makes a difference.
3. I will review and revise my test code where necessary to remove this issue, then upload new versions of each afflicted file after further testing.

Edited July 1, 2017 by BotanicNitro

[Jay Avery]

36 minutes ago, BotanicNitro said:

 

1. I initially started out extending IItemHandler to manage my inventory, but Slot wants an instance of a class that extends IInventory. How would I get a GUI working with IItemHandler? I would prefer not to extend ItemStackHandler, as I wish to store other data that will be related to this inventory, but I'm not too stubborn to consider it if it becomes the only viable option.

Forge has a Slot implementation for IItemHandler inventories - net.minecraftforge.items.SlotItemHandler.

[BotanicNitro]

18 minutes ago, Jay Avery said:

Forge has a Slot implementation for IItemHandler inventories - net.minecraftforge.items.SlotItemHandler.

That's very good to know, thank you.

 

8 hours ago, Choonster said:

You should be using IItemHandler, Forge's replacement for IInventory. You can use or extend ItemStackHandler, the standard IItemHandler implementation.

 

ItemStackHandler implements INBTSerializable, you should use those methods to read it from/write it to NBT. Alternatively, use the IItemHandler capability's IStorage instance.

 

I'm not sure exactly why your code isn't working, but I noticed that you're comparing the ItemStack to ItemStack.EMPTY directly; don't do this. Use ItemStack#isEmpty to check if an ItemStack is empty, ItemStack.EMPTY is just one possible empty ItemStack.

I found that converting my test code to use a similar structure did, in fact, solve the issue with persistence.

Additionally, I found an error in my main codebase that, when fixed, also fixed it there.

If I encounter further issues with persistence in the future, I will be sure to return.

 

The original post has been updated to include the new files.