PREREQUISITES

Make sure you've completed the datagen setup process first.

Setup

First, we'll need our provider. Make a class that extends FabricRecipeProvider. All our recipe generation will happen inside the generate method of our provider.

import java.util.List;
import java.util.concurrent.CompletableFuture;

import net.minecraft.data.server.recipe.RecipeExporter;
import net.minecraft.data.server.recipe.ShapedRecipeJsonBuilder;
import net.minecraft.data.server.recipe.ShapelessRecipeJsonBuilder;
import net.minecraft.item.Items;
import net.minecraft.recipe.Ingredient;
import net.minecraft.recipe.book.RecipeCategory;
import net.minecraft.registry.RegistryWrapper;
import net.minecraft.registry.tag.ItemTags;

import net.fabricmc.fabric.api.datagen.v1.FabricDataOutput;
import net.fabricmc.fabric.api.datagen.v1.provider.FabricRecipeProvider;

public class FabricDocsReferenceRecipeProvider extends FabricRecipeProvider {
	public FabricDocsReferenceRecipeProvider(FabricDataOutput output, CompletableFuture<RegistryWrapper.WrapperLookup> registriesFuture) {
		super(output, registriesFuture);
	}

	@Override
	public void generate(RecipeExporter recipeExporter) {
	}
}

To finish setup, add this provider to your DataGeneratorEntrypoint within the onInitializeDataGenerator method.

pack.addProvider(FabricDocsReferenceRecipeProvider::new);

Shapeless Recipes

Shapeless recipes are fairly straightforward. Just add them to the generate method in your provider:

ShapelessRecipeJsonBuilder.create(RecipeCategory.BUILDING_BLOCKS, Items.DIRT) // You can also specify an int to produce more than one
		.input(Items.COARSE_DIRT) // You can also specify an int to require more than one, or a tag to accept multiple things
		// Create an advancement that gives you the recipe
		.criterion(FabricRecipeProvider.hasItem(Items.COARSE_DIRT), FabricRecipeProvider.conditionsFromItem(Items.COARSE_DIRT))
		.offerTo(recipeExporter);

Shaped Recipes

For a shaped recipe, you define the shape using a String, then define what each char in the String represents.

ShapedRecipeJsonBuilder.create(RecipeCategory.MISC, Items.CRAFTING_TABLE, 4)
		.pattern("ll")
		.pattern("ll")
		.input('l', ItemTags.LOGS) // 'l' means "any log"
		.group("multi_bench") // Put it in a group called "multi_bench" - groups are shown in one slot in the recipe book
		.criterion(FabricRecipeProvider.hasItem(Items.CRAFTING_TABLE), FabricRecipeProvider.conditionsFromItem(Items.CRAFTING_TABLE))
		.offerTo(recipeExporter);
ShapedRecipeJsonBuilder.create(RecipeCategory.MISC, Items.LOOM, 4)
		.pattern("ww")
		.pattern("ll")
		.input('w', ItemTags.WOOL) // 'w' means "any wool"
		.input('l', ItemTags.LOGS)
		.group("multi_bench")
		.criterion(FabricRecipeProvider.hasItem(Items.LOOM), FabricRecipeProvider.conditionsFromItem(Items.LOOM))
		.offerTo(recipeExporter);
FabricRecipeProvider.createDoorRecipe(Items.OAK_DOOR, Ingredient.ofItems(Items.OAK_BUTTON)) // Using a helper method!
		.criterion(FabricRecipeProvider.hasItem(Items.OAK_BUTTON), FabricRecipeProvider.conditionsFromItem(Items.OAK_BUTTON))
		.offerTo(recipeExporter);

TIP

There's a lot of helper methods for creating common recipes. Check out what RecipeProvider has to offer! Use Alt + 7 in IntelliJ to open the structure of a class, including a method list.

Other Recipes

Other recipes work similarly, but require a few extra parameters. For example, smelting recipes need to know how much experience to award.

FabricRecipeProvider.offerSmelting(recipeExporter,
		List.of(Items.BREAD, Items.COOKIE, Items.HAY_BLOCK), // Inputs
		RecipeCategory.FOOD, // Category
		Items.WHEAT, // Output
		0.1f, // Experience
		300, // Cooking time
		"food_to_wheat" // group
);

Custom Recipe Types