Source code for dagster._core.definitions.asset_out

from typing import Any, Mapping, NamedTuple, Optional, Sequence, Type, Union

import dagster._check as check
from dagster._annotations import PublicAttr
from dagster._core.definitions.events import (
    AssetKey,
    CoercibleToAssetKey,
    CoercibleToAssetKeyPrefix,
)
from dagster._core.definitions.input import NoValueSentinel
from dagster._core.definitions.metadata import MetadataUserInput
from dagster._core.definitions.output import Out
from dagster._core.definitions.utils import DEFAULT_IO_MANAGER_KEY
from dagster._core.types.dagster_type import DagsterType, resolve_dagster_type


[docs]class AssetOut(
    NamedTuple(
        "_AssetOut",
        [
            ("key", PublicAttr[Optional[AssetKey]]),
            ("key_prefix", PublicAttr[Optional[Sequence[str]]]),
            ("metadata", PublicAttr[Optional[Mapping[str, Any]]]),
            ("io_manager_key", PublicAttr[str]),
            ("description", PublicAttr[Optional[str]]),
            ("is_required", PublicAttr[bool]),
            ("dagster_type", PublicAttr[Union[DagsterType, Type[NoValueSentinel]]]),
            ("group_name", PublicAttr[Optional[str]]),
        ],
    )
):
    """
    Defines one of the assets produced by a :py:func:`@multi_asset <multi_asset>`.

    Attributes:
        key_prefix (Optional[Union[str, Sequence[str]]]): If provided, the asset's key is the
            concatenation of the key_prefix and the asset's name. When using ``@multi_asset``, the
            asset name defaults to the key of the "outs" dictionary Only one of the "key_prefix" and
            "key" arguments should be provided.
        key (Optional[Union[str, Sequence[str], AssetKey]]): The asset's key. Only one of the
            "key_prefix" and "key" arguments should be provided.
        dagster_type (Optional[Union[Type, DagsterType]]]):
            The type of this output. Should only be set if the correct type can not
            be inferred directly from the type signature of the decorated function.
        description (Optional[str]): Human-readable description of the output.
        is_required (bool): Whether the presence of this field is required. (default: True)
        io_manager_key (Optional[str]): The resource key of the IO manager used for this output.
            (default: "io_manager").
        metadata (Optional[Dict[str, Any]]): A dict of the metadata for the output.
            For example, users can provide a file path if the data object will be stored in a
            filesystem, or provide information of a database table when it is going to load the data
            into the table.
        group_name (Optional[str]): A string name used to organize multiple assets into groups. If
            not provided, the name "default" is used.
    """

    def __new__(
        cls,
        key_prefix: Optional[CoercibleToAssetKeyPrefix] = None,
        key: Optional[CoercibleToAssetKey] = None,
        dagster_type: Union[Type, DagsterType] = NoValueSentinel,
        description: Optional[str] = None,
        is_required: bool = True,
        io_manager_key: Optional[str] = None,
        metadata: Optional[MetadataUserInput] = None,
        group_name: Optional[str] = None,
    ):
        if isinstance(key_prefix, str):
            key_prefix = [key_prefix]

        return super(AssetOut, cls).__new__(
            cls,
            key=AssetKey.from_coerceable(key) if key is not None else None,
            key_prefix=check.opt_list_param(key_prefix, "key_prefix", of_type=str),
            dagster_type=NoValueSentinel
            if dagster_type is NoValueSentinel
            else resolve_dagster_type(dagster_type),
            description=check.opt_str_param(description, "description"),
            is_required=check.bool_param(is_required, "is_required"),
            io_manager_key=check.opt_str_param(
                io_manager_key, "io_manager_key", default=DEFAULT_IO_MANAGER_KEY
            ),
            metadata=check.opt_dict_param(metadata, "metadata", key_type=str),
            group_name=check.opt_str_param(group_name, "group_name"),
        )

    def to_out(self) -> Out:
        return Out(
            dagster_type=self.dagster_type,
            description=self.description,
            metadata=self.metadata,
            is_required=self.is_required,
            io_manager_key=self.io_manager_key,
        )