Registrar

The registrar allows you to manually add and edit datapack registries before Minecraft loads them.

Getting Started

To get started, find your quilt.mod.json and add the following to your entrypoints block:

"entrypoints": {
	"limlib:registrar": "net.myname.modid.MyRegistrar"
}

Of course, replace the entry with the actual path to your class.

At that class, it should look something like this:

public class MyRegistrar implements LimlibRegistrar {

	@Override
	public void registerHooks() {
	}

}

Hooks

Register hooks?! What's a hook?! Good question hypothetical audience member. In this method, you can add a 'hook' to modify a registry. For example, if you had some biomes you wanted to register outside of using json, heres what that might look like.

public class MyRegistrar implements LimlibRegistrar {

	@Override
	public void registerHooks() {
		LimlibRegistryHooks.hook(RegistryKeys.BIOME, (infoLookup, registryKey, registry) -> {
			HolderProvider<PlacedFeature> features = infoLookup.lookup(RegistryKeys.PLACED_FEATURE).get().getter();
			HolderProvider<ConfiguredCarver<?>> carvers = infoLookup.lookup(RegistryKeys.CONFIGURED_CARVER).get().getter();

			registry.register(MyBiomes.MY_BIOME, MyBiome.create(features, carvers), Lifecycle.stable());
		});
	}

}

This LimlibRegistryHooks#hook method takes in two parameters: The registry key of the registry you want to modify; then The actual hook. This hook has three parameters: first The registry lookup of everything vanilla's registered in code; The registry key you're hooking into; and The actual registry itself. Note that this is called after that registry is filled up.

Json Hooks

Now say you want to be a little mischievous? And edit a registry as its being read! Well, look no further!~ You can use a different kind of hook to change a jsonElement as its being read from the loaded datapacks. Here's an example for changing every biomes' sky color to be red.

LimlibRegistryHooks.hook(RegistryKeys.BIOME, (infoLookup, registryKey, registryOps, jsonElement) -> {

	if (jsonElement.getAsJsonObject().has("effects")) {
		JsonObject effects = jsonElement.getAsJsonObject().get("effects").getAsJsonObject();
		effects.addProperty("sky_color", 16711684);
	}

});

This hook has four parameters: first The registry lookup of everything vanilla's registered in code; The registry key you're hooking into; the registryOps (useful for messing with codec); and the actual jsonElement you wish to modify.