Fix for proper handling of relative links for assets of network-loaded STAC items

CHANGELOG.md

@@ -9,6 +9,7 @@
 ### Fixed
 
 - Make `extent` not required for `VerticalSpatialDimension` ([#1596](https://github.com/stac-utils/pystac/pull/1596))
+- `Asset.get_absolute_href()` now properly resolves root relative hrefs ([#1599](https://github.com/stac-utils/pystac/pull/1599))
 
 ## [v1.14.1] - 2025-09-18
 

pystac/asset.py

@@ -105,13 +105,12 @@ def get_absolute_href(self) -> str | None:
             str: The absolute HREF of this asset, or None if an absolute HREF could not
                 be determined.
         """
-        if utils.is_absolute_href(self.href):
+        item_self = self.owner.get_self_href() if self.owner is not None else None
+        if utils.is_absolute_href(self.href, item_self):
             return self.href
         else:
-            if self.owner is not None:
-                item_self = self.owner.get_self_href()
-                if item_self is not None:
-                    return utils.make_absolute_href(self.href, item_self)
+            if item_self is not None:
+                return utils.make_absolute_href(self.href, item_self)
             return None
 
     def to_dict(self) -> dict[str, Any]:
@@ -341,7 +340,7 @@ def make_asset_hrefs_relative(self) -> Assets:
         """
         self_href = self.get_self_href()
         for asset in self.assets.values():
-            if is_absolute_href(asset.href):
+            if is_absolute_href(asset.href, self_href):
                 if self_href is None:
                     raise STACError(
                         "Cannot make asset HREFs relative if no self_href is set."
@@ -360,7 +359,7 @@ def make_asset_hrefs_absolute(self) -> Assets:
         """
         self_href = self.get_self_href()
         for asset in self.assets.values():
-            if not is_absolute_href(asset.href):
+            if not is_absolute_href(asset.href, self_href):
                 if self_href is None:
                     raise STACError(
                         "Cannot make relative asset HREFs absolute "
@@ -380,10 +379,10 @@ def get_self_href(self) -> str | None:
 
 
 def _absolute_href(href: str, owner: Assets | None, action: str = "access") -> str:
-    if utils.is_absolute_href(href):
+    item_self = owner.get_self_href() if owner else None
+    if utils.is_absolute_href(href, item_self):
         return href
     else:
-        item_self = owner.get_self_href() if owner else None
         if item_self is None:
             raise ValueError(
                 f"Cannot {action} file if asset href ('{href}') is relative "

pystac/utils.py

@@ -378,19 +378,26 @@ def make_absolute_href(
         return _make_absolute_href_path(parsed_source, parsed_start, start_is_dir)
 
 
-def is_absolute_href(href: str) -> bool:
+def is_absolute_href(href: str, start_href: str | None = None) -> bool:
     """Determines if an HREF is absolute or not.
 
     May be used on either local file paths or URLs.
 
     Args:
         href : The HREF to consider.
+        start_href : The HREF that will be used as the basis for checking if
+          ``source_href`` is a relative path. Defaults to None.
 
     Returns:
         bool: ``True`` if the given HREF is absolute, ``False`` if it is relative.
     """
     parsed = safe_urlparse(href)
-    return parsed.scheme not in ["", "file"] or os.path.isabs(parsed.path)
+    parsed_start_scheme = "" if start_href is None else safe_urlparse(start_href).scheme
+
+    if parsed_start_scheme in ["", "file"]:
+        return parsed.scheme not in ["", "file"] or os.path.isabs(parsed.path)
+    else:
+        return parsed.scheme not in ["", "file"]
 
 
 def datetime_to_str(dt: datetime, timespec: str = "auto") -> str:

tests/test_asset.py

@@ -102,3 +102,75 @@ def test_delete_asset_relative_no_owner_fails(tmp_asset: pystac.Asset) -> None:
 
     assert asset.href in str(e.value)
     assert os.path.exists(href)
+
+
+@pytest.mark.parametrize(
+    "self_href, asset_href, expected_href_nix, expected_href_win",
+    (
+        (
+            "{tmp_path}/myitem.json",
+            "asset.data",
+            "{tmp_path}/asset.data",
+            "{tmp_path}/asset.data",
+        ),
+        (
+            "{tmp_path}/myitem.json",
+            "/absolute/asset.data",
+            "/absolute/asset.data",
+            "/absolute/asset.data",
+        ),
+        (
+            "{tmp_path}/myitem.json",
+            "d:\\absolute\\asset.data",
+            "{tmp_path}/d:/absolute/asset.data",
+            "d:\\absolute\\asset.data",
+        ),
+        (
+            "http://test.com/stac/catalog/myitem.json",
+            "asset.data",
+            "http://test.com/stac/catalog/asset.data",
+            "http://test.com/stac/catalog/asset.data",
+        ),
+        (
+            "http://test.com/stac/catalog/myitem.json",
+            "/asset.data",
+            "http://test.com/asset.data",
+            "http://test.com/asset.data",
+        ),
+    ),
+)
+def test_asset_get_absolute_href(
+    tmp_asset: pystac.Asset,
+    self_href: str,
+    asset_href: str,
+    expected_href_nix: str,
+    expected_href_win: str,
+) -> None:
+    asset = tmp_asset
+    item = asset.owner
+
+    if not isinstance(item, pystac.Item):
+        raise TypeError("Asset must belong to an Item")
+
+    # Extract temporary path from old item HREF
+    old_item_href = item.get_self_href()
+    if not isinstance(old_item_href, str):
+        raise TypeError("Cannot temporary item href")
+    tmp_path = os.path.dirname(old_item_href)
+
+    # Set the temporary path in the test parameters
+    self_href = self_href.format(tmp_path=tmp_path)
+    asset_href = asset_href.format(tmp_path=tmp_path)
+    expected_href_nix = expected_href_nix.format(tmp_path=tmp_path)
+    expected_href_win = expected_href_win.format(tmp_path=tmp_path)
+
+    # Set the item HREF as per test
+    item.set_self_href(self_href)
+    assert item.get_self_href() == self_href
+
+    # Set the asset HREF as per test and check expected output
+    asset.href = asset_href
+    if os.name == "nt":
+        assert asset.get_absolute_href() == expected_href_win
+    else:
+        assert asset.get_absolute_href() == expected_href_nix

tests/test_utils.py

@@ -197,14 +197,15 @@ def test_make_absolute_href_windows(
 def test_is_absolute_href() -> None:
     # Test cases of (href, expected)
     test_cases = [
-        ("item.json", False),
-        ("./item.json", False),
-        ("../item.json", False),
-        ("http://stacspec.org/item.json", True),
+        ("item.json", False, None),
+        ("./item.json", False, None),
+        ("../item.json", False, None),
+        ("http://stacspec.org/item.json", True, None),
+        ("http://stacspec.org/item.json", True, "http://stacspec.org/"),
     ]
 
-    for href, expected in test_cases:
-        actual = is_absolute_href(href)
+    for href, expected, start_href in test_cases:
+        actual = is_absolute_href(href, start_href)
         assert actual == expected
 
 
@@ -214,15 +215,16 @@ def test_is_absolute_href_os_aware() -> None:
     is_windows = os.name == "nt"
     incl_drive_letter = path_includes_drive_letter()
     test_cases = [
-        ("/item.json", not incl_drive_letter),
-        ("/home/someuser/Downloads/item.json", not incl_drive_letter),
-        ("file:///home/someuser/Downloads/item.json", not incl_drive_letter),
-        ("d:/item.json", is_windows),
-        ("c:/files/more_files/item.json", is_windows),
+        ("/item.json", not incl_drive_letter, None),
+        ("/item.json", False, "http://stacspec.org/"),
+        ("/home/someuser/Downloads/item.json", not incl_drive_letter, None),
+        ("file:///home/someuser/Downloads/item.json", not incl_drive_letter, None),
+        ("d:/item.json", is_windows, None),
+        ("c:/files/more_files/item.json", is_windows, None),
     ]
 
-    for href, expected in test_cases:
-        actual = is_absolute_href(href)
+    for href, expected, start_href in test_cases:
+        actual = is_absolute_href(href, start_href)
         assert actual == expected
 
 
@@ -231,15 +233,15 @@ def test_is_absolute_href_windows() -> None:
     # Test cases of (href, expected)
 
     test_cases = [
-        ("item.json", False),
-        (".\\item.json", False),
-        ("..\\item.json", False),
-        ("c:\\item.json", True),
-        ("http://stacspec.org/item.json", True),
+        ("item.json", False, None),
+        (".\\item.json", False, None),
+        ("..\\item.json", False, None),
+        ("c:\\item.json", True, None),
+        ("http://stacspec.org/item.json", True, None),
     ]
 
-    for href, expected in test_cases:
-        actual = is_absolute_href(href)
+    for href, expected, start_href in test_cases:
+        actual = is_absolute_href(href, start_href)
         assert actual == expected