Add new item_assets access pattern

Author: jsignell

pystac/__init__.py

@@ -33,6 +33,7 @@
     "RangeSummary",
     "Item",
     "Asset",
+    "ItemAssetDefinition",
     "ItemCollection",
     "Provider",
     "ProviderRole",
@@ -81,6 +82,7 @@
 from pystac.summaries import RangeSummary, Summaries
 from pystac.asset import Asset
 from pystac.item import Item
+from pystac.item_assets import ItemAssetDefinition
 from pystac.item_collection import ItemCollection
 from pystac.provider import ProviderRole, Provider
 from pystac.utils import HREF

pystac/collection.py

@@ -20,6 +20,7 @@
 from pystac.asset import Asset, Assets
 from pystac.catalog import Catalog
 from pystac.errors import DeprecatedWarning, ExtensionNotImplemented, STACTypeError
+from pystac.item_assets import ItemAssetDefinition, _ItemAssets
 from pystac.layout import HrefLayoutStrategy
 from pystac.link import Link
 from pystac.provider import Provider
@@ -553,6 +554,7 @@ def __init__(
         self.keywords = keywords
         self.providers = providers
         self.summaries = summaries or Summaries.empty()
+        self._item_assets: _ItemAssets | None = None
 
         self.assets = {}
         if assets is not None:
@@ -731,6 +733,27 @@ def get_item(self, id: str, recursive: bool = False) -> Item | None:
                 return super().get_item(id, recursive=recursive)
             raise e
 
+    @property
+    def item_assets(self) -> dict[str, ItemAssetDefinition] | None:
+        if self._item_assets is None and "item_assets" in self.extra_fields:
+            self._item_assets = _ItemAssets(self)
+        return self._item_assets
+
+    @item_assets.setter
+    def item_assets(
+        self, item_assets: dict[str, ItemAssetDefinition | dict[str, Any]] | None
+    ) -> None:
+        # clear out the cached value
+        self._item_assets = None
+
+        if item_assets is None:
+            self.extra_fields.pop("item_assets")
+        else:
+            self.extra_fields["item_assets"] = {
+                k: v if isinstance(v, dict) else v.to_dict()
+                for k, v in item_assets.items()
+            }
+
     def update_extent_from_items(self) -> None:
         """
         Update datetime and bbox based on all items to a single bbox and time window.

pystac/extensions/base.py

@@ -5,7 +5,6 @@
 from abc import ABC, abstractmethod
 from collections.abc import Iterable
 from typing import (
-    TYPE_CHECKING,
     Any,
     Generic,
     TypeVar,
@@ -14,9 +13,6 @@
 
 import pystac
 
-if TYPE_CHECKING:
-    from pystac.extensions.item_assets import AssetDefinition
-
 VERSION_REGEX = re.compile("/v[0-9].[0-9].*/")
 
 
@@ -158,7 +154,7 @@ def has_extension(cls, obj: S) -> bool:
     @classmethod
     def validate_owner_has_extension(
         cls,
-        asset: pystac.Asset | AssetDefinition,
+        asset: pystac.Asset | pystac.ItemAssetDefinition,
         add_if_missing: bool = False,
     ) -> None:
         """
@@ -190,7 +186,7 @@ def validate_owner_has_extension(
     @classmethod
     def ensure_owner_has_extension(
         cls,
-        asset_or_link: pystac.Asset | AssetDefinition | pystac.Link,
+        asset_or_link: pystac.Asset | pystac.ItemAssetDefinition | pystac.Link,
         add_if_missing: bool = False,
     ) -> None:
         """Given an :class:`~pystac.Asset`, checks if the asset's owner has this

pystac/extensions/classification.py

@@ -16,7 +16,6 @@
 )
 
 import pystac
-from pystac.extensions import item_assets
 from pystac.extensions.base import (
     ExtensionManagementMixin,
     PropertiesExtension,
@@ -27,7 +26,7 @@
 from pystac.serialization.identify import STACJSONDescription, STACVersionID
 from pystac.utils import get_required, map_opt
 
-T = TypeVar("T", pystac.Item, pystac.Asset, item_assets.AssetDefinition, RasterBand)
+T = TypeVar("T", pystac.Item, pystac.Asset, pystac.ItemAssetDefinition, RasterBand)
 
 SCHEMA_URI_PATTERN: str = (
     "https://stac-extensions.github.io/classification/v{version}/schema.json"
@@ -492,7 +491,7 @@ class ClassificationExtension(
     """An abstract class that can be used to extend the properties of
     :class:`~pystac.Item`, :class:`~pystac.Asset`,
     :class:`~pystac.extension.raster.RasterBand`, or
-    :class:`~pystac.extension.item_assets.AssetDefinition` with properties from the
+    :class:`~pystac.ItemAssetDefinition` with properties from the
     :stac-ext:`Classification Extension <classification>`.  This class is generic
     over the type of STAC object being extended.
 
@@ -600,7 +599,7 @@ def ext(cls, obj: T, add_if_missing: bool = False) -> ClassificationExtension[T]
 
         This extension can be applied to instances of :class:`~pystac.Item`,
         :class:`~pystac.Asset`,
-        :class:`~pystac.extensions.item_assets.AssetDefinition`, or
+        :class:`~pystac.ItemAssetDefinition`, or
         :class:`~pystac.extension.raster.RasterBand`.
 
         Raises:
@@ -612,7 +611,7 @@ def ext(cls, obj: T, add_if_missing: bool = False) -> ClassificationExtension[T]
         elif isinstance(obj, pystac.Asset):
             cls.ensure_owner_has_extension(obj, add_if_missing)
             return cast(ClassificationExtension[T], AssetClassificationExtension(obj))
-        elif isinstance(obj, item_assets.AssetDefinition):
+        elif isinstance(obj, pystac.ItemAssetDefinition):
             cls.ensure_owner_has_extension(obj, add_if_missing)
             return cast(
                 ClassificationExtension[T], ItemAssetsClassificationExtension(obj)
@@ -663,17 +662,19 @@ def __repr__(self) -> str:
 
 
 class ItemAssetsClassificationExtension(
-    ClassificationExtension[item_assets.AssetDefinition]
+    ClassificationExtension[pystac.ItemAssetDefinition]
 ):
     properties: dict[str, Any]
-    asset_defn: item_assets.AssetDefinition
+    asset_defn: pystac.ItemAssetDefinition
 
-    def __init__(self, item_asset: item_assets.AssetDefinition):
+    def __init__(self, item_asset: pystac.ItemAssetDefinition):
         self.asset_defn = item_asset
         self.properties = item_asset.properties
 
     def __repr__(self) -> str:
-        return f"<ItemAssetsClassificationExtension AssetDefinition={self.asset_defn}"
+        return (
+            f"<ItemAssetsClassificationExtension ItemAssetDefinition={self.asset_defn}"
+        )
 
 
 class RasterBandClassificationExtension(ClassificationExtension[RasterBand]):

pystac/extensions/datacube.py

@@ -6,13 +6,12 @@
 from typing import Any, Generic, Literal, TypeVar, Union, cast
 
 import pystac
-from pystac.extensions import item_assets
 from pystac.extensions.base import ExtensionManagementMixin, PropertiesExtension
 from pystac.extensions.hooks import ExtensionHooks
 from pystac.utils import StringEnum, get_required, map_opt
 
 T = TypeVar(
-    "T", pystac.Collection, pystac.Item, pystac.Asset, item_assets.AssetDefinition
+    "T", pystac.Collection, pystac.Item, pystac.Asset, pystac.ItemAssetDefinition
 )
 
 SCHEMA_URI = "https://stac-extensions.github.io/datacube/v2.2.0/schema.json"
@@ -619,7 +618,7 @@ def ext(cls, obj: T, add_if_missing: bool = False) -> DatacubeExtension[T]:
         elif isinstance(obj, pystac.Asset):
             cls.ensure_owner_has_extension(obj, add_if_missing)
             return cast(DatacubeExtension[T], AssetDatacubeExtension(obj))
-        elif isinstance(obj, item_assets.AssetDefinition):
+        elif isinstance(obj, pystac.ItemAssetDefinition):
             cls.ensure_owner_has_extension(obj, add_if_missing)
             return cast(DatacubeExtension[T], ItemAssetsDatacubeExtension(obj))
         else:
@@ -691,11 +690,11 @@ def __repr__(self) -> str:
         return f"<AssetDatacubeExtension Item id={self.asset_href}>"
 
 
-class ItemAssetsDatacubeExtension(DatacubeExtension[item_assets.AssetDefinition]):
+class ItemAssetsDatacubeExtension(DatacubeExtension[pystac.ItemAssetDefinition]):
     properties: dict[str, Any]
-    asset_defn: item_assets.AssetDefinition
+    asset_defn: pystac.ItemAssetDefinition
 
-    def __init__(self, item_asset: item_assets.AssetDefinition):
+    def __init__(self, item_asset: pystac.ItemAssetDefinition):
         self.asset_defn = item_asset
         self.properties = item_asset.properties
 

pystac/extensions/eo.py

@@ -14,7 +14,7 @@
 )
 
 import pystac
-from pystac.extensions import item_assets, projection, view
+from pystac.extensions import projection, view
 from pystac.extensions.base import (
     ExtensionManagementMixin,
     PropertiesExtension,
@@ -25,7 +25,7 @@
 from pystac.summaries import RangeSummary
 from pystac.utils import get_required, map_opt
 
-T = TypeVar("T", pystac.Item, pystac.Asset, item_assets.AssetDefinition)
+T = TypeVar("T", pystac.Item, pystac.Asset, pystac.ItemAssetDefinition)
 
 SCHEMA_URI: str = "https://stac-extensions.github.io/eo/v1.1.0/schema.json"
 SCHEMA_URIS: list[str] = [
@@ -409,7 +409,7 @@ def ext(cls, obj: T, add_if_missing: bool = False) -> EOExtension[T]:
         elif isinstance(obj, pystac.Asset):
             cls.ensure_owner_has_extension(obj, add_if_missing)
             return cast(EOExtension[T], AssetEOExtension(obj))
-        elif isinstance(obj, item_assets.AssetDefinition):
+        elif isinstance(obj, pystac.ItemAssetDefinition):
             cls.ensure_owner_has_extension(obj, add_if_missing)
             return cast(EOExtension[T], ItemAssetsEOExtension(obj))
         else:
@@ -536,9 +536,9 @@ def __repr__(self) -> str:
         return f"<AssetEOExtension Asset href={self.asset_href}>"
 
 
-class ItemAssetsEOExtension(EOExtension[item_assets.AssetDefinition]):
+class ItemAssetsEOExtension(EOExtension[pystac.ItemAssetDefinition]):
     properties: dict[str, Any]
-    asset_defn: item_assets.AssetDefinition
+    asset_defn: pystac.ItemAssetDefinition
 
     def _get_bands(self) -> list[Band] | None:
         if BANDS_PROP not in self.properties:
@@ -550,7 +550,7 @@ def _get_bands(self) -> list[Band] | None:
             )
         )
 
-    def __init__(self, item_asset: item_assets.AssetDefinition):
+    def __init__(self, item_asset: pystac.ItemAssetDefinition):
         self.asset_defn = item_asset
         self.properties = item_asset.properties
 

pystac/extensions/ext.py

@@ -1,13 +1,21 @@
 from dataclasses import dataclass
 from typing import Any, Generic, Literal, TypeVar, cast
 
-from pystac import Asset, Catalog, Collection, Item, Link, STACError
+from pystac import (
+    Asset,
+    Catalog,
+    Collection,
+    Item,
+    ItemAssetDefinition,
+    Link,
+    STACError,
+)
 from pystac.extensions.classification import ClassificationExtension
 from pystac.extensions.datacube import DatacubeExtension
 from pystac.extensions.eo import EOExtension
 from pystac.extensions.file import FileExtension
 from pystac.extensions.grid import GridExtension
-from pystac.extensions.item_assets import AssetDefinition, ItemAssetsExtension
+from pystac.extensions.item_assets import ItemAssetsExtension
 from pystac.extensions.mgrs import MgrsExtension
 from pystac.extensions.pointcloud import PointcloudExtension
 from pystac.extensions.projection import ProjectionExtension
@@ -22,8 +30,8 @@
 from pystac.extensions.view import ViewExtension
 from pystac.extensions.xarray_assets import XarrayAssetsExtension
 
-T = TypeVar("T", Asset, AssetDefinition, Link)
-U = TypeVar("U", Asset, AssetDefinition)
+T = TypeVar("T", Asset, ItemAssetDefinition, Link)
+U = TypeVar("U", Asset, ItemAssetDefinition)
 
 EXTENSION_NAMES = Literal[
     "classification",
@@ -107,7 +115,7 @@ def cube(self) -> DatacubeExtension[Collection]:
         return DatacubeExtension.ext(self.stac_object)
 
     @property
-    def item_assets(self) -> dict[str, AssetDefinition]:
+    def item_assets(self) -> dict[str, ItemAssetDefinition]:
         return ItemAssetsExtension.ext(self.stac_object).item_assets
 
     @property
@@ -300,8 +308,8 @@ def xarray(self) -> XarrayAssetsExtension[Asset]:
 
 
 @dataclass
-class ItemAssetExt(_AssetExt[AssetDefinition]):
-    stac_object: AssetDefinition
+class ItemAssetExt(_AssetExt[ItemAssetDefinition]):
+    stac_object: ItemAssetDefinition
 
 
 @dataclass