Handle unbound XML prefixes when strict=False (#35)

Author: mastikamastika

changes/35.feature

@@ -0,0 +1,5 @@
+Handle unbound XML prefixes when strict=False
+
+Allow for unbound XML prefixes when parsing with strict=False.
+This is useful for handling XML documents that may have missing
+namespace declarations.

didl_lite/didl_lite.py

@@ -2,6 +2,7 @@
 """DIDL-Lite (Digital Item Declaration Language) tools for Python."""
 # pylint: disable=too-many-lines
 
+import re
 from typing import (
     Any,
     Dict,
@@ -1073,7 +1074,27 @@ def to_xml_string(*objects: DidlObject) -> bytes:
 def from_xml_string(
     xml_string: str, strict: bool = True
 ) -> List[Union[DidlObject, Descriptor]]:
-    """Convert XML string to DIDL Objects."""
+    """Parse DIDL-Lite XML string."""
+    if not strict:
+        # Find all prefixes used in tags, e.g., <prefix:tag ...>
+        used_prefixes = set(re.findall(r"<([a-zA-Z0-9]+):", xml_string))
+
+        # Find all defined namespaces, e.g., xmlns:prefix=...
+        defined_prefixes = set(re.findall(r"xmlns:([a-zA-Z0-9]+)=", xml_string))
+
+        # Identify prefixes used but not defined.
+        missing_prefixes = (
+            used_prefixes - defined_prefixes - {"DIDL-Lite", "dc", "upnp", "dlna"}
+        )
+
+        # Remove the "if missing_prefixes:" line and just keep the for loop
+        for prefix in missing_prefixes:
+            dlna_ns = 'xmlns:dlna="urn:schemas-dlna-org:metadata-1-0/"'
+            if dlna_ns in xml_string:
+                replacement = f'{dlna_ns} xmlns:{prefix}="http://tempuri.org/{prefix}/"'
+                xml_string = xml_string.replace(dlna_ns, replacement)
+
+    # Proceed with parsing using the (potentially) patched xml_string
     xml_el = defusedxml.ElementTree.fromstring(xml_string)
     return from_xml_el(xml_el, strict)
 

tests/test_didl_lite.py

@@ -680,3 +680,45 @@ def test_item_improper_class_nesting(self) -> None:
 
         item = items[0]
         assert isinstance(item, didl_lite.MusicTrack)
+
+    def test_from_xml_string_unbound_prefix(self) -> None:
+        """Test from_xml_string with unbound namespace prefix."""
+        # The key fix is adding: xmlns="urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/"
+        broken_xml = (
+            '<DIDL-Lite xmlns="urn:schemas-upnp-org:metadata-1-0/DIDL-Lite/" '
+            'xmlns:dc="http://purl.org/dc/elements/1.1/" '
+            'xmlns:upnp="urn:schemas-upnp-org:metadata-1-0/upnp/" '
+            'xmlns:dlna="urn:schemas-dlna-org:metadata-1-0/">'
+            '<item id="1" parentID="0" restricted="1">'
+            "<dc:title>Test Title</dc:title>"
+            "<song:subTitle>Test Subtitle</song:subTitle>"
+            "<upnp:class>object.item.audioItem.musicTrack</upnp:class>"
+            "</item>"
+            "</DIDL-Lite>"
+        )
+
+        # This call should not throw ParseError when strict=False.
+        objs = didl_lite.from_xml_string(broken_xml, strict=False)
+
+        assert len(objs) == 1
+        assert objs[0].title == "Test Title"
+        # Check that the temporary namespace is correctly assigned.
+        assert "sub_title" in objs[0].__dict__
+        assert objs[0].sub_title == "Test Subtitle"
+        assert isinstance(objs[0], didl_lite.MusicTrack)
+
+    def test_music_track_artist_and_genre(self) -> None:
+        """Test MusicTrack artist and genre properties."""
+        track = didl_lite.MusicTrack(
+            id="1",
+            parent_id="0",
+            title="Test",
+            restricted="0",
+            artist="My Artist",
+            genre="My Genre",
+        )
+
+        xml = didl_lite.to_xml_string(track)
+
+        assert b"<upnp:artist>My Artist</upnp:artist>" in xml
+        assert b"<upnp:genre>My Genre</upnp:genre>" in xml