How to create a custom data registry?

[EveryBlu]

I want to create a registry for a custom data file in a data-driven system I'm trying to make. I know how to use forge's built-in registries (for items, blocks, etc), but I have no idea how to setup my own, let alone one for a custom type of data pack file. Any help is appreciated.

[vemerion]

18 hours ago, EveryBlu said:

I want to create a registry for a custom data file in a data-driven system I'm trying to make. I know how to use forge's built-in registries (for items, blocks, etc), but I have no idea how to setup my own, let alone one for a custom type of data pack file. Any help is appreciated.

To create your own data driven system you can extends PreparableReloadListener (or its subclass SimpleJsonResourceReloadListener) and then register it in AddReloadListenerEvent.

[EveryBlu]

On 2/25/2024 at 2:48 PM, vemerion said:

To create your own data driven system you can extends PreparableReloadListener (or its subclass SimpleJsonResourceReloadListener) and then register it in AddReloadListenerEvent.

How do I get my PreparableReloadListener to use in code?

I know how to register it now, but how do I use it in other code?

[vemerion]

3 hours ago, EveryBlu said:

I know how to register it now, but how do I use it in other code?

You can look at the vanilla subclasses to get an idea of how to implement your PreparableReloadListener.

[EveryBlu]

8 hours ago, vemerion said:

You can look at the vanilla subclasses to get an idea of how to implement your PreparableReloadListener.

No like how do I use my new PreperableReloadListener, I know how to set it up now and register it, I just need to know how to use it in other classes.

[Mikul]

I personally create registries using DataPackRegistryEvent.NewRegistry. It's pretty powerful as long as you know how to make codecs.

In some class, make a registry key like so:

public static final ResourceKey<Registry<MyDataType>> MY_REGISTRY = ResourceKey.createRegistryKey(new ResourceLocation(MyMod.MOD_ID, "registry_name"));

This will make a registry that holds objects of type "MyDataType". JSON files stored in data/<datapack_namespace>/modid/registryname/ will be parsed and put into this registry. Note that the directory structure has a folder named after your mod inside your datapack directory, so the actual path would look like: data/my_mod/my_mod/registry_name (or if another mod uses your registry: data/their_mod/my_mod/registry_name.

To register this registry, subscribe to the DataPackRegistryEvent.NewRegistry event on the MOD event bus and call event.dataPackRegistry() for every registry you have. An example of what I'm doing for my mod (this is in the constructor for the main mod file):

IEventBus bus = FMLJavaModLoadingContext.get().getModEventBus();

bus.addListener((DataPackRegistryEvent.NewRegistry event) ->
{   
	event.dataPackRegistry(ModRegistries.INSULATOR_DATA, InsulatorData.CODEC);
});

CODEC is a public static field inside the class for the custom data type I am registering. It holds a Codec<InsulatorData> that tells Minecraft how to serialize/deserialize the data. Most of my data so far can be represented by records, so I use RecordCodecBuilder.create() to do this:

public static final Codec<InsulatorData> CODEC = RecordCodecBuilder.create(instance -> instance.group(
	// Yadda yadda
).apply(instance, InsulatorData::new));

What exactly to put here depends on what you're trying to do, so that's up to you. But basically you're just defining a list of codecs that correspond to the parameters of the record (data type). Most primitive data types have records in the Codec class (ex. Codec.INT) that you can use, and other classes like ResourceLocation have their own codecs as a static field (ex. ResourceLocation.CODEC).

Hopefully this is what you're looking for, and that this helps.

Edited March 5, 2024 by Mikul

[vemerion]

4 hours ago, EveryBlu said:

No like how do I use my new PreperableReloadListener, I know how to set it up now and register it, I just need to know how to use it in other classes.

That completely depends on what your listener is for. For example, the vanilla RecipeManager has a method 'getRecipeFor()' which is used in various places, one of them being the furnace to see if an item can be smelted.

[EveryBlu]

2 hours ago, vemerion said:

That completely depends on what your listener is for. For example, the vanilla RecipeManager has a method 'getRecipeFor()' which is used in various places, one of them being the furnace to see if an item can be smelted.

I mean how do I get a reference of my listener in another class to call these methods? Vanilla code for example gets the RecipeManager via:

someLevelObject.getServer().getRecipeListener()

Do I use mixins to add a "getMyListener()" method in ReloadableServerResources"?

[vemerion]

6 hours ago, EveryBlu said:

I mean how do I get a reference of my listener in another class to call these methods? Vanilla code for example gets the RecipeManager via:

You should save a reference to it before you register it in AddReloadListenerEvent and then you can access that reference from wherever you need it. Here is an example of how Forge itself does it for the LootModifierManager.

Edited March 5, 2024 by vemerion