---

Goal: When a player harvests any dirt variant without a shovel, drop nothing.

---

.mainHand("BLACKLIST", [], "shovel;0;-1")

This bit is doing the heavy lifting for this example. What we've done is told Dropt to match this rule if the main hand item is not (blacklist) a shovel of at least harvest level 0.

The shovel;0;-1 harvest level string tells Dropt to match a shovel with a minimum harvest level of 0 and a maximum harvest level of -1, which is just ignored because it is -1. We then simply inverse that with the BLACKLIST type.

Finally, we tell Dropt that when this rule matches, replace all drops with nothing. This is done by supplying an empty drop to the drop list. Nothing has to be changed to replace all drops because, by default, the replace strategy is REPLACE_ALL.

---

ZenScript

import mods.dropt.Dropt;

Dropt.list("list_name")

  .add(Dropt.rule()
      .matchBlocks(["minecraft:dirt:*"])
      .matchHarvester(Dropt.harvester()
          .type("PLAYER")
          .mainHand("BLACKLIST", [], "shovel;0;-1")
      )
      .addDrop(Dropt.drop())
  );

JSON

{
  "rules": [
    {
      "match": {
        "blocks": {
          "blocks": [
            "minecraft:dirt:*"
          ]
        },
        "harvester": {
          "type": "PLAYER",
          "heldItemMainHand": {
            "type": "BLACKLIST",
            "harvestLevel": "shovel;0;-1"
          }
        }
      },
      "drops": [{}]
    }
  ]
}

DroptAPI

@SubscribeEvent
public void on(DroptLoadRulesEvent event) {

  List<IDroptRuleBuilder> list = new ArrayList<>();

  list.add(DroptAPI.rule()
      .matchBlocks(new String[]{
          "minecraft:dirt:*"
      })
      .matchHarvester(DroptAPI.harvester()
          .type(EnumHarvesterType.PLAYER)
          .mainHand(EnumListType.BLACKLIST, "shovel;0;-1")
      )
      .addDrops(new IDroptDropBuilder[]{
          DroptAPI.drop()
      })
  );

  ResourceLocation resourceLocation = new ResourceLocation("my_mod_id", "rule_list_name");
  int priority = 0;
  DroptAPI.registerRuleList(resourceLocation, priority, list);
}