fix(epub): recognize XML elements independently of namespace prefixes

packages/markitdown/src/markitdown/converters/_epub_converter.py

@@ -3,7 +3,7 @@
 import zipfile
 from urllib.parse import unquote
 from defusedxml import minidom
-from xml.dom.minidom import Document
+from xml.dom.minidom import Document, Element
 
 from typing import BinaryIO, Any, Dict, List, Set
 
@@ -19,6 +19,10 @@
 
 ACCEPTED_FILE_EXTENSIONS = [".epub"]
 
+CONTAINER_NAMESPACE = "urn:oasis:names:tc:opendocument:xmlns:container"
+OPF_NAMESPACE = "http://www.idpf.org/2007/opf"
+DC_NAMESPACE = "http://purl.org/dc/elements/1.1/"
+
 MIME_TYPE_MAPPING = {
     ".html": "text/html",
     ".xhtml": "application/xhtml+xml",
@@ -63,9 +67,9 @@ def convert(
 
             # Locate content.opf
             container_dom = minidom.parse(z.open("META-INF/container.xml"))
-            opf_path = container_dom.getElementsByTagName("rootfile")[0].getAttribute(
-                "full-path"
-            )
+            opf_path = self._get_elements(
+                container_dom, CONTAINER_NAMESPACE, "rootfile"
+            )[0].getAttribute("full-path")
 
             # Parse content.opf
             opf_dom = minidom.parse(z.open(opf_path))
@@ -82,11 +86,11 @@ def convert(
             # Extract manifest items (ID → href mapping)
             manifest = {
                 item.getAttribute("id"): item.getAttribute("href")
-                for item in opf_dom.getElementsByTagName("item")
+                for item in self._get_elements(opf_dom, OPF_NAMESPACE, "item")
             }
 
             # Extract spine order (ID refs)
-            spine_items = opf_dom.getElementsByTagName("itemref")
+            spine_items = self._get_elements(opf_dom, OPF_NAMESPACE, "itemref")
             spine_order = [item.getAttribute("idref") for item in spine_items]
 
             # Convert spine order to actual file paths
@@ -156,6 +160,21 @@ def _resolve_manifest_href(
 
         return candidates[0]
 
+    def _get_elements(
+        self,
+        dom: Document,
+        namespace: str,
+        local_name: str,
+        legacy_name: str | None = None,
+    ) -> List[Element]:
+        # Match namespace URIs, not the arbitrary prefix chosen by the author.
+        nodes = list(dom.getElementsByTagNameNS(namespace, local_name))
+        if nodes:
+            return nodes
+        # Preserve the original tag-name lookup for legacy/malformed namespace
+        # URIs, but only when there are no elements in the standard namespace.
+        return list(dom.getElementsByTagName(legacy_name or local_name))
+
     def _get_text_from_node(self, dom: Document, tag_name: str) -> str | None:
         """Convenience function to extract a single occurrence of a tag (e.g., title)."""
         texts = self._get_all_texts_from_nodes(dom, tag_name)
@@ -167,7 +186,9 @@ def _get_text_from_node(self, dom: Document, tag_name: str) -> str | None:
     def _get_all_texts_from_nodes(self, dom: Document, tag_name: str) -> List[str]:
         """Helper function to extract all occurrences of a tag (e.g., multiple authors)."""
         texts: List[str] = []
-        for node in dom.getElementsByTagName(tag_name):
+        for node in self._get_elements(
+            dom, DC_NAMESPACE, tag_name.removeprefix("dc:"), legacy_name=tag_name
+        ):
             text_parts: List[str] = []
             self._collect_node_text(node, text_parts)
             text_val = "".join(text_parts).strip()

packages/markitdown/tests/test_epub.py

@@ -219,5 +219,104 @@ def test_epub_metadata_and_text_are_unchanged() -> None:
     assert "Chapter text." in result.markdown
 
 
+@pytest.mark.parametrize("prefixed_part", ["container", "package", "metadata"])
+def test_namespace_prefixes_do_not_change_epub_conversion(prefixed_part):
+    original = _build_epub(
+        [("c1", "one.xhtml"), ("c2", "two.xhtml")],
+        ["c2", "c1"],
+        {
+            "OEBPS/one.xhtml": ("First", "FIRST_BODY"),
+            "OEBPS/two.xhtml": ("Second", "SECOND_BODY"),
+        },
+    )
+    archive = io.BytesIO()
+    with zipfile.ZipFile(original) as source, zipfile.ZipFile(archive, "w") as target:
+        for entry in source.infolist():
+            content = source.read(entry)
+            if (
+                prefixed_part == "container"
+                and entry.filename == "META-INF/container.xml"
+            ):
+                text = content.decode().replace("xmlns=", "xmlns:ocf=")
+                for tag in ("container", "rootfiles", "rootfile"):
+                    text = text.replace(f"<{tag}", f"<ocf:{tag}").replace(
+                        f"</{tag}", f"</ocf:{tag}"
+                    )
+                content = text.encode()
+            elif entry.filename == "OEBPS/content.opf":
+                text = content.decode()
+                if prefixed_part == "package":
+                    text = text.replace("xmlns=", "xmlns:opf=")
+                    for tag in (
+                        "package",
+                        "metadata",
+                        "manifest",
+                        "spine",
+                        "itemref",
+                        "item",
+                    ):
+                        text = text.replace(f"<{tag}", f"<opf:{tag}").replace(
+                            f"</{tag}", f"</opf:{tag}"
+                        )
+                elif prefixed_part == "metadata":
+                    text = (
+                        text.replace("xmlns:dc=", "xmlns:book=")
+                        .replace("<dc:", "<book:")
+                        .replace("</dc:", "</book:")
+                    )
+                content = text.encode()
+            target.writestr(entry, content)
+    archive.seek(0)
+    result = EpubConverter().convert(archive, StreamInfo(extension=".epub"))
+    assert result.title == "Encoded Hrefs"
+    text = result.markdown.replace("\\", "")
+    assert "SECOND_BODY" in text and "FIRST_BODY" in text
+    assert text.index("SECOND_BODY") < text.index("FIRST_BODY")
+
+
+@pytest.mark.parametrize(
+    "original_namespace,replacement_namespace",
+    [
+        (
+            "http://www.idpf.org/2007/opf",
+            "http://openebook.org/namespaces/oeb-package/1.0/",
+        ),
+        ("http://purl.org/dc/elements/1.1/", "http://purl.org/dc/elements/1.0/"),
+        ("http://purl.org/dc/elements/1.1/", "http://purl.org/dc/elements/1.1"),
+        ("urn:oasis:names:tc:opendocument:xmlns:container", "urn:legacy:container"),
+        ("urn:oasis:names:tc:opendocument:xmlns:container", ""),
+        ("http://www.idpf.org/2007/opf", ""),
+    ],
+)
+def test_legacy_namespace_uris_keep_metadata_and_chapters(
+    original_namespace, replacement_namespace
+):
+    original = _build_epub(
+        [("c1", "one.xhtml")],
+        ["c1"],
+        {"OEBPS/one.xhtml": ("First", "CHAPTER_BODY")},
+    )
+    archive = io.BytesIO()
+    with zipfile.ZipFile(original) as source, zipfile.ZipFile(archive, "w") as target:
+        for entry in source.infolist():
+            content = source.read(entry)
+            if entry.filename in ("META-INF/container.xml", "OEBPS/content.opf"):
+                text = content.decode().replace(
+                    original_namespace, replacement_namespace
+                )
+                if entry.filename == "OEBPS/content.opf":
+                    text = text.replace(
+                        "</metadata>",
+                        "<dc:creator>Example Author</dc:creator></metadata>",
+                    )
+                content = text.encode()
+            target.writestr(entry, content)
+    archive.seek(0)
+    result = EpubConverter().convert(archive, StreamInfo(extension=".epub"))
+    assert result.title == "Encoded Hrefs"
+    assert "**Authors:** Example Author" in result.markdown
+    assert "CHAPTER_BODY" in result.markdown.replace("\\", "")
+
+
 if __name__ == "__main__":
     raise SystemExit(pytest.main([__file__]))