Datapack Registry Object Generation

Datapack registry objects can be generated for a mod by constructing a new DatapackBuiltinEntriesProvider and providing a RegistrySetBuilder with the new objects to register. The provider must be added to the DataGenerator.

!!! note DatapackBuiltinEntriesProvider is a Forge extension on top of RegistriesDatapackGenerator which properly handles referencing existing datapack registry objects without exploding the entry. So, this documentation will use DatapackBuiltinEntriesProvider.

// On the MOD event bus
@SubscribeEvent
public void gatherData(GatherDataEvent event) {
    event.getGenerator().addProvider(
        // Tell generator to run only when server data are generating
        event.includeServer(),
        output -> new DatapackBuiltinEntriesProvider(
          output,
          event.getLookupProvider(),
          // The builder containing the datapack registry objects to generate
          new RegistrySetBuilder().add(/* ... */),
          // Set of mod ids to generate the datapack registry objects of
          Set.of(MOD_ID)
        )
    );
}

RegistrySetBuilder

A RegistrySetBuilder is responsible for building all datapack registry objects to be used within the game. The builder can add a new entry for a registry, which can then register objects to that registry.

First, a new instance of a RegistrySetBuilder can be initialized by calling the constructor. Then, the #add method (which takes in the ResourceKey of the registry, a RegistryBootstrap consumer containing the BootstapContext to register the objects, and an optional Lifecycle argument to indicate the registry's current lifecycle status) can be called to handle a specific registry for registration.

new RegistrySetBuilder()
  // Create configured features
  .add(Registries.CONFIGURED_FEATURE, bootstrap -> {
    // Register configured features here
  })
  // Create placed features
  .add(Registries.PLACED_FEATURE, bootstrap -> {
    // Register placed features here
  });

!!! note Datapack registries created through Forge can also generate their objects using this builder by also passing in the associated ResourceKey.

Registering with BootstapContext

The #register method in the BootstapContext provided by the builder can be used to register objects. It takes in the ResourceKey representing the registry name of the object, the object to register, and an optional Lifecycle argument to indicate the registry object's current lifecycle status.

public static final ResourceKey<ConfiguredFeature<?, ?>> EXAMPLE_CONFIGURED_FEATURE = ResourceKey.create(
  Registries.CONFIGURED_FEATURE,
  new ResourceLocation(MOD_ID, "example_configured_feature")
);

// In some constant location or argument
new RegistrySetBuilder()
  // Create configured features
  .add(Registries.CONFIGURED_FEATURE, bootstrap -> {
    // Register configured features here
    bootstrap.register(
      // The resource key for the configured feature
      EXAMPLE_CONFIGURED_FEATURE,
      new ConfiguredFeature<>(
        Feature.ORE, // Create an ore feature
        new OreConfiguration(
          List.of(), // Does nothing
          8 // in veins of at most 8
        )
      )
    );
  })
  // Create placed features
  .add(Registries.PLACED_FEATURE, bootstrap -> {
    // Register placed features here
  });

Datapack Registry Object Lookup

Sometimes datapack registry objects may want to use other datapack registry objects or tags containing datapack registry objects. In those cases, you can look up another datapack registry using BootstapContext#lookup to get a HolderGetter. From there, you can get a Holder$Reference to the datapack registry object or a HolderSet$Named for the tag via #getOrThrow by passing in the associated key.

public static final ResourceKey<ConfiguredFeature<?, ?>> EXAMPLE_CONFIGURED_FEATURE = ResourceKey.create(
  Registries.CONFIGURED_FEATURE,
  new ResourceLocation(MOD_ID, "example_configured_feature")
);

public static final ResourceKey<PlacedFeature> EXAMPLE_PLACED_FEATURE = ResourceKey.create(
  Registries.PLACED_FEATURE,
  new ResourceLocation(MOD_ID, "example_placed_feature")
);

// In some constant location or argument
new RegistrySetBuilder()
  // Create configured features
  .add(Registries.CONFIGURED_FEATURE, bootstrap -> {
    // Register configured features here
    bootstrap.register(
      // The resource key for the configured feature
      EXAMPLE_CONFIGURED_FEATURE,
      new ConfiguredFeature(/* ... */)
    );
  })
  // Create placed features
  .add(Registries.PLACED_FEATURE, bootstrap -> {
    // Register placed features here

    // Get configured feature registry
    HolderGetter<ConfiguredFeature<?, ?>> configured = bootstrap.lookup(Registries.CONFIGURED_FEATURE);

    bootstrap.register(
      // The resource key for the placed feature
      EXAMPLE_PLACED_FEATURE,
      new PlacedFeature(
        configured.getOrThrow(EXAMPLE_CONFIGURED_FEATURE), // Get the configured feature
        List.of() // and do nothing to the placement location
      )
    )
  });