Better control on subfolders in generate_subcatalogs

pystac/catalog.py

@@ -665,26 +665,22 @@ def generate_subcatalogs(
         for link in item_links:
             link.resolve_stac_object(root=self.get_root())
             item = cast(pystac.Item, link.target)
-            item_parts = layout_template.get_template_values(item)
+            subcat_ids = layout_template.substitute(item).split("/")
             id_iter = reversed(parent_ids)
             if all(
-                [
-                    "{}".format(id) == next(id_iter, None)
-                    for id in reversed(list(item_parts.values()))
-                ]
+                ["{}".format(id) == next(id_iter, None) for id in reversed(subcat_ids)]
             ):
                 # Skip items for which the sub-catalog structure already
                 # matches the template. The list of parent IDs can include more
                 # elements on the root side, so compare the reversed sequences.
                 keep_item_links.append(link)
                 continue
             curr_parent = self
-            for k, v in item_parts.items():
-                subcat_id = "{}".format(v)
+            for subcat_id in subcat_ids:
                 subcat = curr_parent.get_child(subcat_id)
                 if subcat is None:
-                    subcat_desc = "Catalog of items from {} with {} of {}".format(
-                        curr_parent.id, k, v
+                    subcat_desc = "Catalog of items from {} with id {}".format(
+                        curr_parent.id, subcat_id
                     )
                     subcat = pystac.Catalog(id=subcat_id, description=subcat_desc)
                     curr_parent.add_child(subcat)

tests/test_catalog.py

@@ -413,6 +413,30 @@ def test_generate_subcatalogs_does_not_change_item_count(self) -> None:
                     actual, expected, msg=" for child '{}'".format(child.id)
                 )
 
+    def test_generate_subcatalogs_merge_template_elements(self) -> None:
+        catalog = Catalog(id="test", description="Test")
+        item_properties = [
+            dict(property1=p1, property2=p2) for p1 in ("A", "B") for p2 in (1, 2)
+        ]
+        for ni, properties in enumerate(item_properties):
+            catalog.add_item(
+                Item(
+                    id="item{}".format(ni),
+                    geometry=ARBITRARY_GEOM,
+                    bbox=ARBITRARY_BBOX,
+                    datetime=datetime.utcnow(),
+                    properties=properties,
+                )
+            )
+        result = catalog.generate_subcatalogs("${property1}_${property2}")
+
+        actual_subcats = set([cat.id for cat in result])
+        expected_subcats = set(
+            ["{}_{}".format(d["property1"], d["property2"]) for d in item_properties]
+        )
+        self.assertEqual(len(result), len(expected_subcats))
+        self.assertSetEqual(actual_subcats, expected_subcats)
+
     def test_generate_subcatalogs_can_be_applied_multiple_times(self) -> None:
         catalog = TestCases.test_case_8()