====== Tag Generation ======

The ''[[https://github.com/FabricMC/fabric/blob/1.19.2/fabric-data-generation-api-v1/src/main/java/net/fabricmc/fabric/api/datagen/v1/provider/FabricTagProvider.java|FabricTagProvider<T>]]'' class allows you to generate tag json files.

This page will follow you through all aspects of this provider.

To create a tag generator, create a class that extends ''FabricTagProvider<T>'', where ''T'' is the type of tag you want to generate, and register it at your datagen entrypoint like so:

<code java>
private static class MyTagGenerator extends ItemTagProvider {
   public MyTagGenerator(FabricDataOutput output, CompletableFuture<WrapperLookup> completableFuture) {
        super(output, completableFuture);
   }

   @Override
   protected void configure(WrapperLookup arg) {
   
   }
}

// ...

@Override
public void onInitializeDataGenerator(FabricDataGenerator fabricDataGenerator) {
    // ...
    fabricDataGenerator.addProvider(MyTagGenerator::new);
    // ...
}
</code>

The ''FabricTagProvider<T>'' class supports all supported tags, make sure to change the ''Registry'' in the constructor to the type you are generating your tags for.

===== Adding a tag =====

To add a tag, simply call the ''getOrCreateTagBuilder'' method with your supplied ''TagKey<T>'' in the ''configure(WrapperLookup arg)'' method like so:

<code java>
private static final TagKey<Item> SMELLY_ITEMS = TagKey.of(RegistryKeys.ITEM_KEY, new Identifier("mymod:smelly_items"));
 
@Override
protected void configure(WrapperLookup arg) {
     // This creates a tag builder, where we add slime balls, rotten flesh and everything in the minecraft:dirt item tag.
     getOrCreateTagBuilder(SMELLY_ITEMS)
              .add(Items.SLIME_BALL)
              .add(Items.ROTTEN_FLESH)
              .addOptionalTag(ItemTags.DIRT);
     // This will automatically generate "assets/mymod/tags/items/smelly_items.json" in the "generated" folder.
}
</code>

Output from the example above:

<file javascript smelly_items.json>
{
  "replace": false,
  "values": [
    "minecraft:slime_ball",
    "minecraft:rotten_flesh",
    {
      "id": "#minecraft:dirt",
      "required": false
    }
  ]
}
</file>

===== Adding stuff to the builder =====

To add an item to your tag builder, simply call ''add(Item item)''.

If you want to add a tag to your builder, make sure to call ''addOptionalTag(TagKey<T> tag)'', as the tag's contents may not be loaded during data generation. If you are certain the tag is loaded, call ''addTag(TagKey<T> tag)''

Various overloads exist for ''addTag'', ''addOptionalTag'' and ''addItem'' that accepts ''Identifier''s, ''String''s and ''RegistryKey<T>''s

If you want to forcefully add a tag, ignoring the broken format, you can use ''forceAddTag(TagKey<T> tag)''

Finally, if you want your tag to replace pre-existing tags, you can use ''setReplace(boolean replace)''

An example that uses all of these methods can be found here:

<code java>
private static final TagKey<Item> SMELLY_ITEMS = TagKey.of(RegistryKeys.ITEM_KEY, new Identifier("mymod:smelly_items"));

@Override
protected void configure(WrapperLookup arg) {
     getOrCreateTagBuilder(SMELLY_ITEMS)
                    .add(Items.SLIME_BALL)
                    .add(Items.ROTTEN_FLESH)
                    .addOptionalTag(ItemTags.DIRT)
                    .add(new Identifier("minecraft", "wooden_planks"))
                    .forceAddTag(ItemTags.BANNERS)
                    .setReplace(true)
                    .add(Items.ROTTEN_FLESH.getRegistryEntry().registryKey());
}
</code>