core[patch]:: XML parser to cover the case when the xml only contains the root level tag (#17456)

Description: Fix xml parser to handle strings that only contain the root tag Issue: N/A Dependencies: None Twitter handle: N/A A valid xml text can contain only the root level tag. Example: <body> Some text here </body> The example above is a valid xml string. If parsed with the current implementation the result is {"body": []}. This fix checks if the root level text contains any non-whitespace character and if that's the case it returns {root.tag: root.text}. The result is that the above text is correctly parsed as {"body": "Some text here"} @ale-delfino Thank you for contributing to LangChain! Checklist: - [x] PR title: Please title your PR "package: description", where "package" is whichever of langchain, community, core, experimental, etc. is being modified. Use "docs: ..." for purely docs changes, "templates: ..." for template changes, "infra: ..." for CI changes. - Example: "community: add foobar LLM" - [x] PR message: **Delete this entire template message** and replace it with the following bulleted list - **Description:** a description of the change - **Issue:** the issue # it fixes, if applicable - **Dependencies:** any dependencies required for this change - **Twitter handle:** if your PR gets announced, and you'd like a mention, we'll gladly shout you out! - [x] Pass lint and test: Run `make format`, `make lint` and `make test` from the root of the package(s) you've modified to check that you're passing lint and testing. See contribution guidelines for more information on how to write/run tests, lint, etc: https://python.langchain.com/docs/contributing/ - [x] Add tests and docs: If you're adding a new integration, please include 1. a test for the integration, preferably unit tests that do not rely on network access, 2. an example notebook showing its use. It lives in `docs/docs/integrations` directory. Additional guidelines: - Make sure optional dependencies are imported within a function. - Please do not add dependencies to pyproject.toml files (even optional ones) unless they are required for unit tests. - Most PRs should not touch more than one package. - Changes should be backwards compatible. - If you are adding something to community, do not re-import it in langchain. If no one reviews your PR within a few days, please @-mention one of @baskaryan, @efriis, @eyurtsev, @hwchase17. --------- Co-authored-by: Eugene Yurtsev <eyurtsev@gmail.com>
2 months ago · 0df76bee37
parent 124ab79c23
commit 0df76bee37
2 changed files with 33 additions and 9 deletions
--- a/libs/core/langchain_core/output_parsers/xml.py
+++ b/libs/core/langchain_core/output_parsers/xml.py
@ -155,7 +155,7 @@ class XMLOutputParser(BaseTransformOutputParser):
    def get_format_instructions(self) -> str:
        return XML_FORMAT_INSTRUCTIONS.format(tags=self.tags)

-    def parse(self, text: str) -> Dict[str, List[Any]]:
+    def parse(self, text: str) -> Dict[str, Union[str, List[Any]]]:
        # Try to find XML string within triple backticks
        # Imports are temporarily placed here to avoid issue with caching on CI
        # likely if you're reading this you can move them to the top of the file
@ -207,9 +207,13 @@ class XMLOutputParser(BaseTransformOutputParser):
                yield output
        streaming_parser.close()

-    def _root_to_dict(self, root: ET.Element) -> Dict[str, List[Any]]:
+    def _root_to_dict(self, root: ET.Element) -> Dict[str, Union[str, List[Any]]]:
        """Converts xml tree to python dictionary."""
-        result: Dict[str, List[Any]] = {root.tag: []}
+        if root.text and bool(re.search(r"\S", root.text)):
+            # If root text contains any non-whitespace character it
+            # returns {root.tag: root.text}
+            return {root.tag: root.text}
+        result: Dict = {root.tag: []}
        for child in root:
            if len(child) == 0:
                result[root.tag].append({child.tag: child.text})
--- a/libs/core/tests/unit_tests/output_parsers/test_xml_parser.py
+++ b/libs/core/tests/unit_tests/output_parsers/test_xml_parser.py
@ -45,8 +45,8 @@ DEF_RESULT_EXPECTED = {

 async def _test_parser(parser: XMLOutputParser, content: str) -> None:
    """Test parser."""
-    xml_content = parser.parse(content)
-    assert DEF_RESULT_EXPECTED == xml_content
+    assert parser.parse(content) == DEF_RESULT_EXPECTED
+    assert await parser.aparse(content) == DEF_RESULT_EXPECTED

    assert list(parser.transform(iter(content))) == [
        {"foo": [{"bar": [{"baz": None}]}]},
@ -54,10 +54,6 @@ async def _test_parser(parser: XMLOutputParser, content: str) -> None:
        {"foo": [{"baz": "tag"}]},
    ]

-    async def _as_iter(iterable: Iterable[str]) -> AsyncIterator[str]:
-        for item in iterable:
-            yield item
-
    chunks = [chunk async for chunk in parser.atransform(_as_iter(content))]

    assert list(chunks) == [
@ -67,6 +63,30 @@ async def _test_parser(parser: XMLOutputParser, content: str) -> None:
    ]


+ROOT_LEVEL_ONLY = """<?xml version="1.0" encoding="UTF-8"?>
+<body>Text of the body.</body>
+"""
+
+ROOT_LEVEL_ONLY_EXPECTED = {"body": "Text of the body."}
+
+
+async def _as_iter(iterable: Iterable[str]) -> AsyncIterator[str]:
+    for item in iterable:
+        yield item
+
+
+async def test_root_only_xml_output_parser() -> None:
+    """Test XMLOutputParser when xml only contains the root level tag"""
+    xml_parser = XMLOutputParser(parser="xml")
+    assert xml_parser.parse(ROOT_LEVEL_ONLY) == {"body": "Text of the body."}
+    assert await xml_parser.aparse(ROOT_LEVEL_ONLY) == {"body": "Text of the body."}
+    assert list(xml_parser.transform(iter(ROOT_LEVEL_ONLY))) == [
+        {"body": "Text of the body."}
+    ]
+    chunks = [chunk async for chunk in xml_parser.atransform(_as_iter(ROOT_LEVEL_ONLY))]
+    assert chunks == [{"body": "Text of the body."}]
+
+
@pytest.mark.parametrize(
    "content",
    [