Create a Data Generator

This page answers one question: how to write a working data generator file. For the overall concepts, see the Runtime Data Generation System. For field value syntax, see Placeholder Parsers.

Where It Goes

Generator files belong in the generator/ directory of the corresponding handler, not directly under assets/ or data/:

• Datapack: [game directory]/croparia/datapack/generator/
• Resource pack: [game directory]/croparia/resourcepack/generator/

The generated outputs will then be written to:

• Datapack: [game directory]/croparia/datapack/data/
• Resource pack: [game directory]/croparia/resourcepack/assets/

Supported formats:

• toml
• cdg
• json

toml is the recommended default.

Minimal Example

registry = "croparia:crops"
path = "example/recipes/${id.path}.json"
template = """
{
  "type": "minecraft:crafting_shapeless",
  "ingredients": [
    { "item": "${fruit}" }
  ],
  "result": {
    "id": "${seed}",
    "count": 1
  }
}
"""

This means:

• iterate over croparia:crops
• calculate path once for each entry
• fill template with the current entry
• generate multiple independent files

Core Fields

• registry: which generation entry set should be iterated
  • common values:
    • croparia:crops
    • croparia:melons
    • croparia:elements
• path: relative output path; this field is itself a template
  • example:

path = "${id.namespace}/models/item/${seed.path}.json"

• template: the final file content to write; this is also a template string
  • example:

template = """
{
  "parent": "croparia:item/template_seed"
}
"""

• type: generator type

  • available values:
    • croparia:generator (default)
    • croparia:aggregated
    • croparia:lang

• startup: whether this generator should run before the server has fully started

• enabled: whether the generator is enabled; useful for temporarily disabling a file without deleting it

  • example:

enabled = false

• whitelist
  • purpose: only generate for specific entries instead of traversing the whole registry
  • common use cases: debugging, partial overrides
  • example:

whitelist = ["croparia:coal", "croparia:iron"]

Generator Types

Standard Generator croparia:generator

The default type. One entry usually produces one file; if multiple entries resolve to the same target path, the later write overrides the earlier one.

Good for:

• recipes
• models
• loot tables
• blockstates

registry = "croparia:crops"
startup = true
path = "${id.namespace}/models/item/${seed.path}.json"
template = """
{
  "parent": "croparia:item/template_seed"
}
"""

Aggregated Generator croparia:aggregated

Each entry first produces a piece of content, then all pieces are merged into one shared template. This is a good fit for files like tags, where many entries must be combined into one result.

Extra field:

• content

registry = "croparia:crops"
type = "croparia:aggregated"
startup = true
path = "croparia/tags/item/seeds/crops.json"
content = '    "${seed}"'
template = """
{
  "replace": false,
  "values": [
${content}
  ]
}
"""

Language Generator croparia:lang

This type is designed for translatable entries. It splits output by language and injects the _lang placeholder for use inside templates.

Good for:

• language files

registry = "croparia:crops"
type = "croparia:lang"
startup = true
path = "${id.namespace}/lang/${lang}.json"
template = '"${translation_key}": "${translations.get(_lang)}"'

For language-related fields, see Placeholder Parsers.