Items in FD specific containers do not transfer NBT data to Data Components

[ChrysanthCow]

Minecraft version

1.21.1

Farmer's Delight version

1.2.1

NeoForge version

21.1.221

Description

Original Issue

Original Issue Description (Written by @Unariginal)
When upgrading our server to 1.21.1 from 1.20.1, all items stack counts, enchantments, and shulker contents have been erased from Cabinets in the world. Both for every compat cabinets and built-in farmer's delight cabinets.

This would also affect Cooking Pots and any other block entity that may contain items.

Quote from @Patbox

Assuming all itemstacks are stored in Items nbt field, you could use vanilla transform for this.
The code for defining layout of block entities is relatively simple, so here's mine for reference: https://github.com/Patbox/PolyDecorations/blob/master/src/main/java/eu/pb4/polydecorations/mixin/datafixer/Schema1460Mixin.java

Worth noting this will only allow data fixing of container data on version upgrades.
This would also apply to any other data change mojang does in future.

Steps to reproduce

1. Load into a Farmer's Delight world on 1.20.1
2. Place items inside a FD specific container.
3. Reload the world jn 1.21.1.
4. Witness item loss.

Mod list

I'll have to get you a modlist as soon as I test this on a minimal instance. The original find was on Refabricated which makes this irrelevant.

Logs

No response

Minimal instance

• I have tested this on a minimal instance

Performance and shader mods

• I am using performance or shader mods

[ChrysanthCow]

This is DFU shenanigans, I can drop a PR if necessary, but hopefully Patbox's impl reference is a good enough lead to fix this.

[ChrysanthCow]

Fixed link to relevant impl reference:

https://github.com/Patbox/PolyDecorations/blob/master/src/main/java/eu/pb4/polydecorations/mixin/datafixer/V1460Mixin.java

[vectorwing]

I tried migrating a 1.20.1 world manually into 1.21.1, and all containers seemed to save their data normally; I couldn't replicate their issue, unless the migration they did is different from moving a world between versions.

Though I never introduced any specific implementations to migrate this data, Minecraft seemed to handle that on my end.

This makes me wonder if Neo has something in place to convert that, but I'm unsure. I'll ask for more context about this; in case it actually is an issue on both loaders, we can try the DFU mixin; but I might need to ask some questions before that.

[vectorwing]

Update: I misread the issue. I thought the items were wiped, but only their NBT data was. It did happen during the migration on my end, so yes, that's an issue here too.

[vectorwing]

This is DFU shenanigans, I can drop a PR if necessary, but hopefully Patbox's impl reference is a good enough lead to fix this.

I'd be interested in that, as I'm not sure which DFU classes need to be targeted here, given there are dozens of them.

[Patbox]

Here are ones most relevant: https://github.com/Patbox/brewery/tree/main/src/main/java/eu/pb4/brewery/mixin/datafixer

With:

• ItemStackComponizationFix: Handles converting your own custom item nbt to new components system
• V1460: Handles entity, block entity data and old nbt item data
• V3818_3: Handles components format

You could use some other Vxxxx ones to also do similar things, but I choose these as they are earliest one to make sense (with V1460 being around 1.13, making it good for defning BE that were nearly-always present and with V3818_3 being first one adding all vanilla component definitions).

[vectorwing]

I tried implementing the mixin above, and it did indeed work for standard containers. 👍

However, it failed with FD's workstations. This is because their "Items" NBT is stored inside an "Inventory" NBT, due to how ItemStackHandler serializes. I realize now that I could've saved it with merge() rather than put() to keep it at the base level.

@Patbox do you know if it's possible to datafix an NBT tag nested within another? I tried this, but it didn't work:

schema.register(map, farmersdelight$mod("cutting_board"), string ->
				DSL.optionalFields(
						"Inventory", DSL.optionalFields("Items", References.ITEM_STACK.in(schema))
				));

I only saw this kind of nesting in the registerType method, so I'm unsure if it's possible to reach into a nested tag without registering a type.

[Patbox]

You want a list of items, not a single stack I imagine

schema.register(map, farmersdelight$mod("cutting_board"), string ->
				DSL.optionalFields(
						"Inventory", DSL.optionalFields("Items", DSL.list(References.ITEM_STACK.in(schema)))
				));

should do the job

[vectorwing]

It worked! Didn't even notice that was in the registerInventory method. 😅

I'll fiddle with defining the Cooking Pot components, and see if it can restore its data.

[vectorwing]

@Patbox I tried looking into the schemas you mixed in, and yours seems to mixin to a method which doesn't exist on my end:

https://github.com/Patbox/brewery/blob/8e5a1357e55e0b15624ddff20c80cd44b0c7932e/src/main/java/eu/pb4/brewery/mixin/datafixer/V3818_3Mixin.java#L18

There is no "components" in V3818_3, only a registerTypes() method. Is this the method I should use, or is there something different?

When I checked the old versions of this schema, they all refered to a "method_" reference, which I assume wasn't mapped before, but still didn't match registerTypes().

[Patbox]

Looking at 26.1 there is components method at least. Don't have any older dev env rn to check, but guess it could be a lambda / something else before?

[Patbox]

Okay checked and it was a lambda method before, guess it changed between 1.21.1 and 26.1

[vectorwing]

How can I find a reference to a lambda method, in this case? I assume you're referring to this, judging from the code: