Issue #573 metadata_from_stac: add support for "item_assets"

CHANGELOG.md

@@ -14,6 +14,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Document PEP 723 based Python UDF dependency declarations ([Open-EO/openeo-geopyspark-driver#237](https://github.com/Open-EO/openeo-geopyspark-driver/issues/237))
 - Added more `openeo.api.process.Parameter` helpers to easily create "bounding_box", "date", "datetime", "geojson" and "temporal_interval" parameters for UDP construction.
 - Added convenience method `Connection.load_stac_from_job(job)` to easily load the results of a batch job with the `load_stac` process ([#566](https://github.com/Open-EO/openeo-python-client/issues/566))
+- `load_stac`/`metadata_from_stac`: add support for extracting band info from "item_assets" in collection metadata ([#573](https://github.com/Open-EO/openeo-python-client/issues/573))
 
 ### Changed
 

openeo/_testing.py

@@ -0,0 +1,34 @@
+"""
+Utilities for testing
+"""
+
+import json
+from pathlib import Path
+from typing import Callable, Optional, Union
+
+
+class TestDataLoader:
+    """
+    Helper to resolve paths to test data files, loadt them as JSON, and optionally preprocess them.
+
+    It's recommended to set this up as a fixture in your test suite,
+    e.g. from conftest.py:
+
+        @pytest.fixture
+        def test_data() -> TestDataLoader:
+            return TestDataLoader(root=Path(__file__).parent / "data")
+    """
+
+    def __init__(self, root: Union[str, Path]):
+        self.data_root = Path(root)
+
+    def get_path(self, filename: Union[str, Path]) -> Path:
+        """Get absolute path to a test data file"""
+        return self.data_root / filename
+
+    def load_json(self, filename: Union[str, Path], preprocess: Optional[Callable[[str], str]] = None) -> dict:
+        """Parse data from JSON file"""
+        data = self.get_path(filename).read_text(encoding="utf8")
+        if preprocess:
+            data = preprocess(data)
+        return json.loads(data)

openeo/metadata.py

@@ -2,7 +2,7 @@
 
 import logging
 import warnings
-from typing import Any, Callable, List, NamedTuple, Optional, Tuple, Union
+from typing import Any, Callable, Dict, List, NamedTuple, Optional, Set, Tuple, Union
 
 import pystac
 
@@ -107,6 +107,7 @@ class Band(NamedTuple):
 
 
 class BandDimension(Dimension):
+    # TODO #575 support unordered bands and avoid assumption that band order is known.
     def __init__(self, name: str, bands: List[Band]):
         super().__init__(type="bands", name=name)
         self.bands = bands
@@ -534,6 +535,8 @@ def metadata_from_stac(url: str) -> CubeMetadata:
     :return: A :py:class:`CubeMetadata` containing the DataCube band metadata from the url.
     """
 
+    # TODO move these nested functions and other logic to _StacMetadataParser
+
     def get_band_metadata(eo_bands_location: dict) -> List[Band]:
         # TODO: return None iso empty list when no metadata?
         return [
@@ -573,6 +576,10 @@ def is_band_asset(asset: pystac.Asset) -> bool:
                 for asset_band in asset_bands:
                     if asset_band.name not in get_band_names(bands):
                         bands.append(asset_band)
+        if collection.ext.has("item_assets"):
+            # TODO #575 support unordered band names and avoid conversion to a list.
+            bands = list(_StacMetadataParser().get_bands_from_item_assets(collection.ext.item_assets))
+
     elif isinstance(stac_object, pystac.Catalog):
         catalog = stac_object
         bands = get_band_metadata(catalog.extra_fields.get("summaries", {}))
@@ -586,3 +593,69 @@ def is_band_asset(asset: pystac.Asset) -> bool:
     temporal_dimension = TemporalDimension(name="t", extent=[None, None])
     metadata = CubeMetadata(dimensions=[band_dimension, temporal_dimension])
     return metadata
+
+
+class _StacMetadataParser:
+    """
+    Helper to extract openEO metadata from STAC metadata resource
+    """
+
+    def __init__(self):
+        # TODO: toggles for how to handle strictness, warnings, logging, etc
+        pass
+
+    def _get_band_from_eo_bands_item(self, eo_band: Union[dict, pystac.extensions.eo.Band]) -> Band:
+        if isinstance(eo_band, pystac.extensions.eo.Band):
+            return Band(
+                name=eo_band.name,
+                common_name=eo_band.common_name,
+                wavelength_um=eo_band.center_wavelength,
+            )
+        elif isinstance(eo_band, dict) and "name" in eo_band:
+            return Band(
+                name=eo_band["name"],
+                common_name=eo_band.get("common_name"),
+                wavelength_um=eo_band.get("center_wavelength"),
+            )
+        else:
+            raise ValueError(eo_band)
+
+    def get_bands_from_eo_bands(self, eo_bands: List[Union[dict, pystac.extensions.eo.Band]]) -> List[Band]:
+        """
+        Extract bands from STAC `eo:bands` array
+
+        :param eo_bands: List of band objects, as dict or `pystac.extensions.eo.Band` instances
+        """
+        # TODO: option to skip bands that failed to parse in some way?
+        return [self._get_band_from_eo_bands_item(band) for band in eo_bands]
+
+    def _get_bands_from_item_asset(
+        self, item_asset: pystac.extensions.item_assets.AssetDefinition
+    ) -> Union[List[Band], None]:
+        """Get bands from a STAC 'item_assets' asset definition."""
+        if item_asset.ext.has("eo"):
+            if item_asset.ext.eo.bands is not None:
+                return self.get_bands_from_eo_bands(item_asset.ext.eo.bands)
+        elif "eo:bands" in item_asset.properties:
+            # TODO: skip this in strict mode?
+            _log.warning("Extracting band info from 'eo:bands' metadata, but 'eo' STAC extension was not declared.")
+            return self.get_bands_from_eo_bands(item_asset.properties["eo:bands"])
+
+    def get_bands_from_item_assets(
+        self, item_assets: Dict[str, pystac.extensions.item_assets.AssetDefinition]
+    ) -> Set[Band]:
+        """
+        Get bands extracted from "item_assets" objects (defined by "item-assets" extension,
+        in combination with "eo" extension) at STAC Collection top-level,
+
+        Note that "item_assets" in STAC is a mapping, so the band order is undefined,
+        which is why we return a set of bands here.
+
+        :param item_assets: a STAC `item_assets` mapping
+        """
+        bands = set()
+        for item_asset in item_assets.values():
+            asset_bands = self._get_bands_from_item_asset(item_asset)
+            if asset_bands:
+                bands.update(asset_bands)
+        return bands

tests/__init__.py

@@ -5,11 +5,13 @@
 
 
 def get_test_resource(relative_path: str) -> Path:
+    # TODO: migrate to TestDataLoader
     dir = Path(os.path.dirname(os.path.realpath(__file__)))
     return dir / relative_path
 
 
 def load_json_resource(relative_path, preprocess: Callable = None) -> dict:
+    # TODO: migrate to TestDataLoader
     with get_test_resource(relative_path).open("r+") as f:
         data = f.read()
         if preprocess:

tests/conftest.py

@@ -4,6 +4,7 @@
 
 import pytest
 
+from openeo._testing import TestDataLoader
 from openeo.util import ensure_dir
 
 pytest_plugins = "pytester"
@@ -25,3 +26,8 @@ def tmp_openeo_config_home(tmp_path):
     path = ensure_dir(Path(str(tmp_path)) / "openeo-conf")
     with mock.patch.dict("os.environ", {"OPENEO_CONFIG_HOME": str(path)}):
         yield path
+
+
+@pytest.fixture
+def test_data() -> TestDataLoader:
+    return TestDataLoader(root=Path(__file__).parent / "data")

tests/data/stac/collections/agera5_daily01.json

@@ -0,0 +1,82 @@
+{
+  "type": "Collection",
+  "id": "agera5_daily",
+  "stac_version": "1.0.0",
+  "description": "ERA5",
+  "links": [
+    {
+      "rel": "self",
+      "type": "application/json",
+      "href": "https://stac.test/collections/agera5_daily"
+    }
+  ],
+  "stac_extensions": [
+    "https://stac-extensions.github.io/item-assets/v1.0.0/schema.json",
+    "https://stac-extensions.github.io/eo/v1.1.0/schema.json"
+  ],
+  "item_assets": {
+    "2m_temperature_min": {
+      "type": "image/tiff; application=geotiff",
+      "title": "2m temperature min 24h",
+      "eo:bands": [
+        {
+          "name": "2m_temperature_min",
+          "description": "temperature 2m above ground (Kelvin)"
+        }
+      ]
+    },
+    "2m_temperature_max": {
+      "type": "image/tiff; application=geotiff",
+      "eo:bands": [
+        {
+          "name": "2m_temperature_max",
+          "description": "temperature 2m above ground (Kelvin)"
+        }
+      ]
+    },
+    "dewpoint_temperature_mean": {
+      "type": "image/tiff; application=geotiff",
+      "title": "2m dewpoint temperature",
+      "eo:bands": [
+        {
+          "name": "dewpoint_temperature_mean",
+          "description": "dewpoint temperature 2m above ground (Kelvin)"
+        }
+      ]
+    },
+    "vapour_pressure": {
+      "eo:bands": [
+        {
+          "name": "vapour_pressure"
+        }
+      ]
+    }
+  },
+  "title": "agERA5 data",
+  "extent": {
+    "spatial": {
+      "bbox": [
+        [
+          -180,
+          -90,
+          180,
+          90
+        ]
+      ]
+    },
+    "temporal": {
+      "interval": [
+        [
+          "2010-01-01T00:00:00Z",
+          "2024-06-12T00:00:00Z"
+        ]
+      ]
+    }
+  },
+  "keywords": [
+    "ERA5"
+  ],
+  "summaries": {},
+  "assets": {},
+  "license": "proprietary"
+}

tests/test_metadata.py

@@ -1,7 +1,8 @@
 from __future__ import annotations
 
 import json
-from typing import List
+import re
+from typing import List, Union
 
 import pytest
 
@@ -835,8 +836,34 @@ def filter_bbox(self, bbox):
     ],
 )
 def test_metadata_from_stac(tmp_path, test_stac, expected):
-
     path = tmp_path / "stac.json"
     path.write_text(json.dumps(test_stac))
     metadata = metadata_from_stac(path)
     assert metadata.band_names == expected
+
+
+@pytest.mark.parametrize("eo_extension_is_declared", [False, True])
+def test_metadata_from_stac_collection_bands_from_item_assets(test_data, tmp_path, eo_extension_is_declared, caplog):
+    stac_data = test_data.load_json("stac/collections/agera5_daily01.json")
+    stac_data["stac_extensions"] = [
+        ext
+        for ext in stac_data["stac_extensions"]
+        if (not ext.startswith("https://stac-extensions.github.io/eo/") or eo_extension_is_declared)
+    ]
+    assert (
+        any(ext.startswith("https://stac-extensions.github.io/eo/") for ext in stac_data["stac_extensions"])
+        == eo_extension_is_declared
+    )
+    path = tmp_path / "stac.json"
+    path.write_text(json.dumps(stac_data))
+
+    metadata = metadata_from_stac(path)
+    assert sorted(metadata.band_names) == [
+        "2m_temperature_max",
+        "2m_temperature_min",
+        "dewpoint_temperature_mean",
+        "vapour_pressure",
+    ]
+
+    if not eo_extension_is_declared:
+        assert "Extracting band info from 'eo:bands' metadata, but 'eo' STAC extension was not declared." in caplog.text