How to Save and Load Data to the world

[squidlex]

I am following the read the docs article here but am struggling to get my head around it.

Quote

Each SD implementation must subtype the WorldSavedData class.

I'm replacing it with the SavedData class which I believe is what I'm after.

Here's my class so far:

import net.minecraft.nbt.CompoundTag;
import net.minecraft.server.MinecraftServer;
import net.minecraft.world.level.saveddata.SavedData;

public class FactionSavedData extends SavedData {

	public FactionSavedData create() {
		return new FactionSavedData();

	}
	
	public FactionSavedData load(CompoundTag tag) {
		FactionSavedData data = this.create();
		return data;
	}

	@Override
	public CompoundTag save(CompoundTag tag) {
		return tag;
	}

	public void generateFile(MinecraftServer server) {
		server.overworld().getDataStorage().computeIfAbsent(this::load, this::create, "faction");
	}
	
}

My issue is that I'm not sure how to actually save and load data using this class. For example, say I wanted to save and load an integer value to the overworld.

Thank you for your help!

[squidlex]

1 hour ago, diesieben07 said:

Create fields in your class holding the data you want to save. In your case an integer. Then you need to save the data to the provided CompoundTag in the save method. Your load, create and generateFile methods need to be static. In load you then load the data and apply it to the newly created instance.

Whenever you change anything about the data you need to call setDirty, so that Minecraft knows your data needs saving.

Thank you for your help! Sorry to trouble you, but there's a couple things I still don't understand.

Here's my updated class:

import net.minecraft.nbt.CompoundTag;
import net.minecraft.server.MinecraftServer;
import net.minecraft.world.level.saveddata.SavedData;

public class FactionSavedData extends SavedData {
	
	private int test = 2;

	public int getTest() {
		return this.test;
	}

	public void setTest(int test) {
		this.test = test;
		this.setDirty();
	}

	public static FactionSavedData create() {
		return new FactionSavedData();
	}
	
	public static FactionSavedData load(CompoundTag tag) {
		FactionSavedData data = create();
		int testInt = tag.getInt("test");
		data.test = testInt;
		return data;
	}

	public CompoundTag save(CompoundTag tag) {
		tag.putInt("test", test);
		return tag;
	}

	public static void generateFile(MinecraftServer server) {
		server.overworld().getDataStorage().computeIfAbsent(FactionSavedData::load, FactionSavedData::create, "faction");
	}
	
}

I'm not sure if the first parameter of tag.putInt() is an identifying factor that I can set as anything or if it has to be a numerical Id.

From here I'm not sure when to run the generateFile method, right now I'm doing it here which is most likely incorrect:

@Mod.EventBusSubscriber(modid = Minetopia.MODID, bus = Bus.FORGE)
public class DataStorageEvents {

	@SubscribeEvent
	public static void worldSave(WorldEvent.Save event) {
		FactionSavedData.generateFile(event.getWorld().getServer());
	}
	
	@SubscribeEvent
	public static void worldLoad(WorldEvent.Load event) {
		
	}
	
}

and I'm trying to access my saved data as such as I'm not sure what to pass into the load method:

CompoundTag tag = new CompoundTag();
FactionSavedData test = FactionSavedData.load(tag);
int testInt = test.getTest();

 

[squidlex]

2 hours ago, diesieben07 said:

You need to call generateFile (not sure why you named it like that) whenever you want access to your data. You do not need WorldEvent.Save or WorldEvent.Load.

I see, thank you! It was called that because I was misunderstanding the method's purpose.

It now works, thanks