Storing/Retrieving NBT data in an itemstack in 1.21

[positivevibes]

I'm a bit confused as how to get/store custom nbt data in itemstacks on the fly in version 1.21. After a lot of googling I have found that in the past the ItemStack class had the functions getTagCompound() and setTagCompound(), however they seem to have been deprecated? It's unfortunate because that seemed so straight forward and I can't find much info on the subject otherwise. Apologies if this isn't worded nicely as I am still pretty new to minecraft modding. Any help would be appreciated.

[positivevibes]

Upon further inspection of the wiki I have discovered Capabilities which seems to suit my needs instead. Apologies.

[Choonster]

Item Capabilities haven't been re-implemented in 1.21 yet, you can use Vanilla's Data Components system instead. See DataComponents and the related classes.

[positivevibes]

Okay, so I actually downgraded the mod to 1.20.6 because I did not want to have to deal with vanilla datacomponents. I followed a youtube tutorial and now have a capability I made attach to my modded item. However I am now unsure how to actually retrieve and manipulate the capability of an itemstack. I saw a getCapability function in some tutorials but that seems to have been deprecated...

[Choonster]

The situation is the same in 1.20.6. Data Components were introduced in 1.20.5/1.20.6 and Item Capabilities haven't been re-implemented since then.

[positivevibes]

Okay, I'm glad I made a backup then. I'm confused as to where there is any information on how to work with Data Components. I don't see anything about it on the Forge docs or any tutorials on this in general unless I'm missing it somehow. I can see the DataComponents decompiled class file but I'm not sure how to work with it. Maybe it's beyond my technical expertise?

[Choonster]

I don't think there's any documentation on them yet, I mainly just looked at the Vanilla code when implementing mine.

You can see a fairly simple example here:

• Registration: https://github.com/Choonster-Minecraft-Mods/TestMod3/blob/f3bea10d5f455fa0904056caafd8c844b6fd13ae/src/main/java/choonster/testmod3/init/ModDataComponents.java#L50-L58
• Item Registration: https://github.com/Choonster-Minecraft-Mods/TestMod3/blob/f3bea10d5f455fa0904056caafd8c844b6fd13ae/src/main/java/choonster/testmod3/init/ModItems.java#L264-L266
• Usage: https://github.com/Choonster-Minecraft-Mods/TestMod3/blob/f3bea10d5f455fa0904056caafd8c844b6fd13ae/src/main/java/choonster/testmod3/world/item/EntityCheckerItem.java

[positivevibes]

Wow this looks a lot simpler than I thought it would be. Especially compared to the setup I had to do for capabilities. I'll look at all this and update if I have any issues ty

[positivevibes]

Okay, so I got everything set up and should have my data component registered. However when I try to register my modded item with the data component added to it, I get an error saying that the registry object (for the data component) is not present. I tried changing the order in which things are registered in the mod startup to no avail.

[Choonster]

Forge fires RegisterEvent (which is used internally by DeferredRegister) for each registry in a specific order, so changing the registration order in your code won't help. I haven't actually been able to run my mod since 1.20.6 because I'm waiting on Item Capabilities, so I haven't encountered this error myself.

It looks like you can't use your DataComponentType during Item registration, so you probably need to get/add it on demand with getOrDefault and set, instead of in registration.

[positivevibes]

Thanks. I removed the data component from item registration and the game boots fine now. However now when I try to call the set() method on my item stack during the item's useOn method, it still throws an error that the registry object is not present. I have registered the data component along with all of my other modded content in the main mod class, so I am at a genuine loss as to why this is still happening. I am new to these forums, am I allowed to link the github repo?

[Choonster]

Have you registered the DeferredRegister with the mod event bus? You can link your GitHub repo.

[positivevibes]

Yes it should be registered? Here's the link to the github: https://github.com/positivevibes123/MinecraftExplosiveMod hopefully it should be public.

I have everything registered in the MyMod.java file. The other java files of interest are ModDataComponents.java and RemoteItem.java

[Choonster]

The repository is private.

[positivevibes]

My bad, it should be public now

[Choonster]

https://github.com/positivevibes123/MinecraftExplosiveMod/blob/3dfabe6cd67213db484737c8cce650583dd894f1/src/main/java/com/gmail/damoruso321/bomb/datacomponents/ModDataComponents.java#L19

This should be DATA_COMPONENT_TYPES.register(eventBus), not eventBus.register(DATA_COMPONENT_TYPES).

[positivevibes]

Can’t believe I missed that ty, I’ll update the code when I’m able to hopefully no more issues after that lol

[positivevibes]

I think I've finally got it working. Thanks for helping with this issue it was quite a learning experience lol