PERF: maintain root when signing ItemCollections (#30)

Losing the root collection was causing `to_dict()` on signed `ItemCollections` to be extremely slow, like stac-utils/pystac#546. By preserving the root catalog stac-utils/pystac-client#72, it's much faster.

planetary_computer/sas.py

@@ -179,12 +179,11 @@ def sign_item_collection(item_collection: ItemCollection) -> ItemCollection:
         a "msft:expiry" property is added to the Item properties indicating the
         earliest expiry time for any assets that were signed.
     """
-    return ItemCollection.from_dict(
-        {
-            "type": "FeatureCollection",
-            "features": [sign(item).to_dict() for item in item_collection],
-        }
-    )
+    new = item_collection.clone()
+    for item in new:
+        for key in item.assets:
+            _sign_asset_in_place(item.assets[key])
+    return new
 
 
 @sign.register(ItemSearch)

tests/data-files/catalog.json

@@ -0,0 +1,29 @@
+{
+  "type": "Catalog",
+  "id": "microsoft-pc-demo",
+  "stac_version": "1.0.0",
+  "description": "Microsoft Planetary Computer STAC API",
+  "links": [
+    {
+      "rel": "root",
+      "href": "./catalog.json",
+      "type": "application/json"
+    },
+    {
+      "rel": "item",
+      "href": "./sample-item.json",
+      "type": "application/json"
+    },
+    {
+      "rel": "item",
+      "href": "./sample-tabular-item.json",
+      "type": "application/json"
+    },
+    {
+      "rel": "item",
+      "href": "./sample-zarr-item.json",
+      "type": "application/json"
+    }
+  ],
+  "stac_extensions": []
+}

tests/data-files/sample-item.json

@@ -105,7 +105,13 @@
             "roles": ["logo"]
         }
     },
-    "links": [],
+    "links": [
+        {
+            "rel": "root",
+            "href": "./catalog.json",
+            "type": "application/json"
+        }
+    ],
     "stac_extensions":[
         "eo",
         "projection"

tests/data-files/sample-tabular-item.json

@@ -23,7 +23,13 @@
         "datetime": "2020-06-01T00:00:00Z"
     },
     "geometry": null,
-    "links": [],
+    "links": [
+        {
+            "rel": "root",
+            "href": "./catalog.json",
+            "type": "application/json"
+        }
+    ],
     "assets": {
         "data": {
             "href": "abfs://cpdata/raw/fia/plot.parquet",

tests/data-files/sample-zarr-item.json

@@ -588,7 +588,13 @@
             ]
         ]
     },
-    "links": [],
+    "links": [
+        {
+            "rel": "root",
+            "href": "./catalog.json",
+            "type": "application/json"
+        }
+    ],
     "assets": {
         "zarr-https": {
             "href": "https://ai4edataeuwest.blob.core.windows.net/gridmet/gridmet.zarr",

tests/test_signing.py

@@ -1,6 +1,4 @@
 import os
-import json
-from typing import Any, Dict
 import unittest
 from urllib.parse import parse_qs, urlparse
 from pathlib import Path
@@ -35,31 +33,37 @@
 HERE = Path(__file__).parent
 
 
-def get_sample_item_dict() -> Dict[str, Any]:
-    file_path = HERE.joinpath("data-files/sample-item.json").absolute()
-    with open(file_path) as json_file:
-        return json.load(json_file)
+def resolve(item: Item) -> Item:
+    item.resolve_links()
+    return item
 
 
 def get_sample_item() -> Item:
-    return Item.from_dict(get_sample_item_dict())
+    file_path = os.fspath(HERE.joinpath("data-files/sample-item.json"))
+    return resolve(Item.from_file(file_path))
 
 
 def get_sample_zarr_item() -> Item:
     file_path = os.fspath(HERE.joinpath("data-files/sample-zarr-item.json"))
-    return Item.from_file(file_path)
+    return resolve(Item.from_file(file_path))
 
 
 def get_sample_tabular_item() -> Item:
     file_path = os.fspath(HERE.joinpath("data-files/sample-tabular-item.json"))
-    return Item.from_file(file_path)
+    return resolve(Item.from_file(file_path))
 
 
 def get_sample_item_collection() -> ItemCollection:
     return ItemCollection([get_sample_item()])
 
 
 class TestSigning(unittest.TestCase):
+    def assertRootResolved(self, item: Item) -> None:
+        root_link = item.get_root_link()
+        self.assertIsNotNone(root_link)
+        assert root_link  # for type checker
+        self.assertTrue(root_link.is_resolved())
+
     def assertSigned(self, url: str) -> None:
         # Ensure the signed item has an "se" URL parameter added to it,
         # which indicates it has been signed
@@ -96,6 +100,7 @@ def test_signed_assets(self) -> None:
         signed_item = pc.sign(get_sample_item())
         self.verify_signed_urls_in_item(signed_item)
         self.verify_asset_owner(signed_item)
+        self.assertRootResolved(signed_item)
 
     def test_read_signed_asset(self) -> None:
         signed_href = pc.sign(SENTINEL_THUMBNAIL)
@@ -107,6 +112,7 @@ def test_signed_item_collection(self) -> None:
         self.assertEqual(len(list(signed_item_collection)), 1)
         for signed_item in signed_item_collection:
             self.verify_signed_urls_in_item(signed_item)
+            self.assertRootResolved(signed_item)
 
     def test_search_and_sign(self) -> None:
         # Filter out a resource warning coming from within the pystac-client search
@@ -158,13 +164,15 @@ def test_sign_zarr_item(self) -> None:
             "credential",
             result.assets["zarr-abfs"].extra_fields["xarray:storage_options"],
         )
+        self.assertRootResolved(item)
 
     def test_sign_tabular_item(self) -> None:
         item = get_sample_tabular_item()
         result = pc.sign(item)
         self.assertIn(
             "credential", result.assets["data"].extra_fields["table:storage_options"]
         )
+        self.assertRootResolved(item)
 
 
 class TestUtils(unittest.TestCase):