Maybe Data

Maybe Data is a super simple, lightweight library that allows you to conditionally load data.

Maybe Data will only attempt to load when the mod is installed (= a mod bundles Maybe Data), and when the condition at the top of the recipe file is met.

Recipes

resources/data/modid/mayberecipes/golden_apple.json

{
  "condition": {
    "modid": "moreapples"
  },
  "recipe": {
    "type": "minecraft:crafting_shaped",
    "pattern": [
      "###",
      "#X#",
      "###"
    ],
    "key": {
      "#": {
        "item": "minecraft:diamond"
      },
      "X": {
        "item": "minecraft:apple"
      }
    },
    "result": {
      "item": "minecraft:golden_apple"
    }
  }
}

This recipe will only load when Maybe Data is installed (More Apples / another mod might JIJ it), and when the moreapples modid exists. Simple, right?

Loot Tables

Add the following json block to the top level of your loot table .json file (in the same directory as vanilla):

"condition": {
    "modid": "testmod"
}

Example:

{
  "condition": {
    "modid": "testmod"
  },
  "type": "minecraft:block",
  // ... rest of loot table here
}

If the required modid is not present when datapacks are loaded, the loot table will be skipped.

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Looking for more conditional control? Check out LibCD. This mod is MIT and built for the Fabric Loader.