NBT

Literals

profile: nbt = {"name": "Alex", "health": 20, "active": True, "position": [10, 64, -4], "settings": {"particles": False}}
empty: nbt = {}

NBT arrays may contain different NBT-compatible value kinds. Keys must be string literals.

Bracket access

profile["health"] = 18
health: int = profile["health"]
settings: nbt = profile["settings"]
particles: bool = profile["settings"]["particles"]

NBT does not support property syntax: use profile["health"], never profile.health. Field reads need an expected type, normally supplied by a typed variable declaration.

Functions

def update(profile: nbt) -> nbt:
    profile["active"] = True
    return profile

Whole NBT variables can be passed to and returned from functions. Structured return data uses runtime storage because Minecraft /return itself only carries an integer result.

Output and length

say(profile) displays the compound, while say(profile["name"]) displays a selected field. len(profile) returns the number of keys in the compound.

Entity data

Entity values expose their Minecraft NBT through the same bracket-only syntax:

target: entity? = @s
uuid: list[int] = target["UUID"]
health: int = target["Health"]
name: str = target["CustomName"]
memories: nbt = target["Brain"]["memories"]
effects: list[nbt] = target["active_effects"]

DataCraft resolves the entity through its registered UUID tag and emits data get entity or data modify ... set from entity as appropriate for the destination type. Any NBT list or array can use list[int], list[bool], list[str], or list[nbt]; DataCraft generates matching list metadata dynamically for indexing and iteration. Entity NBT keys must be string literals.

Entity NBT fields are writable using the same bracket-only paths:

target["Health"] = 10
target["CustomName"] = "Alex"
target["Brain"]["memories"] = {"home": [1, 2, 3]}
target["active_effects"] = effects

The assigned value may be an NBT-compatible literal or an int, bool, str, list, or nbt variable. DataCraft stages the value in temporary storage, resolves the entity by its registered UUID tag, writes the field, and removes the temporary data. Entity NBT keys must be string literals, and compound fields still use bracket syntax rather than property syntax.

Typed NBT lists may contain compound literals, nested compounds and lists, or existing nbt variables:

speed: nbt = {"id": "speed", "duration": 200}
effects: list[nbt] = [
    speed,
    {"id": "strength", "duration": 100, "flags": [True, False]}
]

Each element is stored as a compound and receives nbt runtime type metadata, so it remains usable when indexed or iterated.