from __future__ import annotations
import asyncio
import inspect
import logging
import re
from typing import (
Callable,
Iterator,
List,
Optional,
Sequence,
Set,
Union,
cast,
)
import aiohttp
import requests
from langchain_core.documents import Document
from langchain_core.utils.html import extract_sub_links
from langchain_community.document_loaders.base import BaseLoader
logger = logging.getLogger(__name__)
def _metadata_extractor(
raw_html: str, url: str, response: Union[requests.Response, aiohttp.ClientResponse]
) -> dict:
"""Extract metadata from raw html using BeautifulSoup."""
content_type = getattr(response, "headers").get("Content-Type", "")
metadata = {"source": url, "content_type": content_type}
try:
from bs4 import BeautifulSoup
except ImportError:
logger.warning(
"The bs4 package is required for default metadata extraction. "
"Please install it with `pip install -U beautifulsoup4`."
)
return metadata
soup = BeautifulSoup(raw_html, "html.parser")
if title := soup.find("title"):
metadata["title"] = title.get_text()
if description := soup.find("meta", attrs={"name": "description"}):
metadata["description"] = description.get("content", None)
if html := soup.find("html"):
metadata["language"] = html.get("lang", None)
return metadata
[docs]
class RecursiveUrlLoader(BaseLoader):
"""Recursively load all child links from a root URL.
**Security Note**: This loader is a crawler that will start crawling
at a given URL and then expand to crawl child links recursively.
Web crawlers should generally NOT be deployed with network access
to any internal servers.
Control access to who can submit crawling requests and what network access
the crawler has.
While crawling, the crawler may encounter malicious URLs that would lead to a
server-side request forgery (SSRF) attack.
To mitigate risks, the crawler by default will only load URLs from the same
domain as the start URL (controlled via prevent_outside named argument).
This will mitigate the risk of SSRF attacks, but will not eliminate it.
For example, if crawling a host which hosts several sites:
https://some_host/alice_site/
https://some_host/bob_site/
A malicious URL on Alice's site could cause the crawler to make a malicious
GET request to an endpoint on Bob's site. Both sites are hosted on the
same host, so such a request would not be prevented by default.
See https://python.langchain.com/v0.2/docs/security/
Setup:
This class has no required additional dependencies. You can optionally install
``beautifulsoup4`` for richer default metadata extraction:
.. code-block:: bash
pip install -U beautifulsoup4
Instantiate:
.. code-block:: python
from langchain_community.document_loaders import RecursiveUrlLoader
loader = RecursiveUrlLoader(
"https://docs.python.org/3.9/",
# max_depth=2,
# use_async=False,
# extractor=None,
# metadata_extractor=None,
# exclude_dirs=(),
# timeout=10,
# check_response_status=True,
# continue_on_failure=True,
# prevent_outside=True,
# base_url=None,
# ...
)
Lazy load:
.. code-block:: python
docs = []
docs_lazy = loader.lazy_load()
# async variant:
# docs_lazy = await loader.alazy_load()
for doc in docs_lazy:
docs.append(doc)
print(docs[0].page_content[:100])
print(docs[0].metadata)
.. code-block:: python
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8" /><
{'source': 'https://docs.python.org/3.9/', 'content_type': 'text/html', 'title': '3.9.19 Documentation', 'language': None}
Async load:
.. code-block:: python
docs = await loader.aload()
print(docs[0].page_content[:100])
print(docs[0].metadata)
.. code-block:: python
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta charset="utf-8" /><
{'source': 'https://docs.python.org/3.9/', 'content_type': 'text/html', 'title': '3.9.19 Documentation', 'language': None}
Content parsing / extraction:
By default the loader sets the raw HTML from each link as the Document page
content. To parse this HTML into a more human/LLM-friendly format you can pass
in a custom ``extractor`` method:
.. code-block:: python
# This example uses `beautifulsoup4` and `lxml`
import re
from bs4 import BeautifulSoup
def bs4_extractor(html: str) -> str:
soup = BeautifulSoup(html, "lxml")
return re.sub(r"\n\n+", "\n\n", soup.text).strip()
loader = RecursiveUrlLoader(
"https://docs.python.org/3.9/",
extractor=bs4_extractor,
)
print(loader.load()[0].page_content[:200])
.. code-block:: python
3.9.19 Documentation
Download
Download these documents
Docs by version
Python 3.13 (in development)
Python 3.12 (stable)
Python 3.11 (security-fixes)
Python 3.10 (security-fixes)
Python 3.9 (securit
Metadata extraction:
Similarly to content extraction, you can specify a metadata extraction function
to customize how Document metadata is extracted from the HTTP response.
.. code-block:: python
import aiohttp
import requests
from typing import Union
def simple_metadata_extractor(
raw_html: str, url: str, response: Union[requests.Response, aiohttp.ClientResponse]
) -> dict:
content_type = getattr(response, "headers").get("Content-Type", "")
return {"source": url, "content_type": content_type}
loader = RecursiveUrlLoader(
"https://docs.python.org/3.9/",
metadata_extractor=simple_metadata_extractor,
)
loader.load()[0].metadata
.. code-block:: python
{'source': 'https://docs.python.org/3.9/', 'content_type': 'text/html'}
Filtering URLs:
You may not always want to pull every URL from a website. There are four parameters
that allow us to control what URLs we pull recursively. First, we can set the
``prevent_outside`` parameter to prevent URLs outside of the ``base_url`` from
being pulled. Note that the ``base_url`` does not need to be the same as the URL we
pass in, as shown below. We can also use ``link_regex`` and ``exclude_dirs`` to be
more specific with the URLs that we select. In this example, we only pull websites
from the python docs, which contain the string "index" somewhere and are not
located in the FAQ section of the website.
.. code-block:: python
loader = RecursiveUrlLoader(
"https://docs.python.org/3.9/",
prevent_outside=True,
base_url="https://docs.python.org",
link_regex=r'<a\\s+(?:[^>]*?\\s+)?href="([^"]*(?=index)[^"]*)"',
exclude_dirs=['https://docs.python.org/3.9/faq']
)
docs = loader.load()
.. code-block:: python
['https://docs.python.org/3.9/',
'https://docs.python.org/3.9/py-modindex.html',
'https://docs.python.org/3.9/genindex.html',
'https://docs.python.org/3.9/tutorial/index.html',
'https://docs.python.org/3.9/using/index.html',
'https://docs.python.org/3.9/extending/index.html',
'https://docs.python.org/3.9/installing/index.html',
'https://docs.python.org/3.9/library/index.html',
'https://docs.python.org/3.9/c-api/index.html',
'https://docs.python.org/3.9/howto/index.html',
'https://docs.python.org/3.9/distributing/index.html',
'https://docs.python.org/3.9/reference/index.html',
'https://docs.python.org/3.9/whatsnew/index.html']
""" # noqa: E501
[docs]
def __init__(
self,
url: str,
max_depth: Optional[int] = 2,
use_async: Optional[bool] = None,
extractor: Optional[Callable[[str], str]] = None,
metadata_extractor: Optional[_MetadataExtractorType] = None,
exclude_dirs: Optional[Sequence[str]] = (),
timeout: Optional[int] = 10,
prevent_outside: bool = True,
link_regex: Union[str, re.Pattern, None] = None,
headers: Optional[dict] = None,
check_response_status: bool = False,
continue_on_failure: bool = True,
*,
base_url: Optional[str] = None,
autoset_encoding: bool = True,
encoding: Optional[str] = None,
) -> None:
"""Initialize with URL to crawl and any subdirectories to exclude.
Args:
url: The URL to crawl.
max_depth: The max depth of the recursive loading.
use_async: Whether to use asynchronous loading.
If True, lazy_load function will not be lazy, but it will still work in the
expected way, just not lazy.
extractor: A function to extract document contents from raw HTML.
When extract function returns an empty string, the document is
ignored. Default returns the raw HTML.
metadata_extractor: A function to extract metadata from args: raw HTML, the
source url, and the requests.Response/aiohttp.ClientResponse object
(args in that order).
Default extractor will attempt to use BeautifulSoup4 to extract the
title, description and language of the page.
..code-block:: python
import requests
import aiohttp
def simple_metadata_extractor(
raw_html: str, url: str, response: Union[requests.Response, aiohttp.ClientResponse]
) -> dict:
content_type = getattr(response, "headers").get("Content-Type", "")
return {"source": url, "content_type": content_type}
exclude_dirs: A list of subdirectories to exclude.
timeout: The timeout for the requests, in the unit of seconds. If None then
connection will not timeout.
prevent_outside: If True, prevent loading from urls which are not children
of the root url.
link_regex: Regex for extracting sub-links from the raw html of a web page.
headers: Default request headers to use for all requests.
check_response_status: If True, check HTTP response status and skip
URLs with error responses (400-599).
continue_on_failure: If True, continue if getting or parsing a link raises
an exception. Otherwise, raise the exception.
base_url: The base url to check for outside links against.
autoset_encoding: Whether to automatically set the encoding of the response.
If True, the encoding of the response will be set to the apparent
encoding, unless the `encoding` argument has already been explicitly set.
encoding: The encoding of the response. If manually set, the encoding will be
set to given value, regardless of the `autoset_encoding` argument.
""" # noqa: E501
self.url = url
self.max_depth = max_depth if max_depth is not None else 2
self.use_async = use_async if use_async is not None else False
self.extractor = extractor if extractor is not None else lambda x: x
metadata_extractor = (
metadata_extractor
if metadata_extractor is not None
else _metadata_extractor
)
self.autoset_encoding = autoset_encoding
self.encoding = encoding
self.metadata_extractor = _wrap_metadata_extractor(metadata_extractor)
self.exclude_dirs = exclude_dirs if exclude_dirs is not None else ()
if any(url.startswith(exclude_dir) for exclude_dir in self.exclude_dirs):
raise ValueError(
f"Base url is included in exclude_dirs. Received base_url: {url} and "
f"exclude_dirs: {self.exclude_dirs}"
)
self.timeout = timeout
self.prevent_outside = prevent_outside if prevent_outside is not None else True
self.link_regex = link_regex
self.headers = headers
self.check_response_status = check_response_status
self.continue_on_failure = continue_on_failure
self.base_url = base_url if base_url is not None else url
def _get_child_links_recursive(
self, url: str, visited: Set[str], *, depth: int = 0
) -> Iterator[Document]:
"""Recursively get all child links starting with the path of the input URL.
Args:
url: The URL to crawl.
visited: A set of visited URLs.
depth: Current depth of recursion. Stop when depth >= max_depth.
"""
if depth >= self.max_depth:
return
# Get all links that can be accessed from the current URL
visited.add(url)
try:
response = requests.get(url, timeout=self.timeout, headers=self.headers)
if self.encoding is not None:
response.encoding = self.encoding
elif self.autoset_encoding:
response.encoding = response.apparent_encoding
if self.check_response_status and 400 <= response.status_code <= 599:
raise ValueError(f"Received HTTP status {response.status_code}")
except Exception as e:
if self.continue_on_failure:
logger.warning(
f"Unable to load from {url}. Received error {e} of type "
f"{e.__class__.__name__}"
)
return
else:
raise e
content = self.extractor(response.text)
if content:
yield Document(
page_content=content,
metadata=self.metadata_extractor(response.text, url, response),
)
# Store the visited links and recursively visit the children
sub_links = extract_sub_links(
response.text,
url,
base_url=self.base_url,
pattern=self.link_regex,
prevent_outside=self.prevent_outside,
exclude_prefixes=self.exclude_dirs,
continue_on_failure=self.continue_on_failure,
)
for link in sub_links:
# Check all unvisited links
if link not in visited:
yield from self._get_child_links_recursive(
link, visited, depth=depth + 1
)
async def _async_get_child_links_recursive(
self,
url: str,
visited: Set[str],
*,
session: Optional[aiohttp.ClientSession] = None,
depth: int = 0,
) -> List[Document]:
"""Recursively get all child links starting with the path of the input URL.
Args:
url: The URL to crawl.
visited: A set of visited URLs.
depth: To reach the current url, how many pages have been visited.
"""
if not self.use_async:
raise ValueError(
"Async functions forbidden when not initialized with `use_async`"
)
if depth >= self.max_depth:
return []
# Disable SSL verification because websites may have invalid SSL certificates,
# but won't cause any security issues for us.
close_session = session is None
session = (
session
if session is not None
else aiohttp.ClientSession(
connector=aiohttp.TCPConnector(ssl=False),
timeout=aiohttp.ClientTimeout(total=self.timeout),
headers=self.headers,
)
)
visited.add(url)
try:
async with session.get(url) as response:
text = await response.text()
if self.check_response_status and 400 <= response.status <= 599:
raise ValueError(f"Received HTTP status {response.status}")
except (aiohttp.client_exceptions.InvalidURL, Exception) as e:
if close_session:
await session.close()
if self.continue_on_failure:
logger.warning(
f"Unable to load {url}. Received error {e} of type "
f"{e.__class__.__name__}"
)
return []
else:
raise e
results = []
content = self.extractor(text)
if content:
results.append(
Document(
page_content=content,
metadata=self.metadata_extractor(text, url, response),
)
)
if depth < self.max_depth - 1:
sub_links = extract_sub_links(
text,
url,
base_url=self.base_url,
pattern=self.link_regex,
prevent_outside=self.prevent_outside,
exclude_prefixes=self.exclude_dirs,
continue_on_failure=self.continue_on_failure,
)
# Recursively call the function to get the children of the children
sub_tasks = []
to_visit = set(sub_links).difference(visited)
for link in to_visit:
sub_tasks.append(
self._async_get_child_links_recursive(
link, visited, session=session, depth=depth + 1
)
)
next_results = await asyncio.gather(*sub_tasks)
for sub_result in next_results:
if isinstance(sub_result, Exception) or sub_result is None:
# We don't want to stop the whole process, so just ignore it
# Not standard html format or invalid url or 404 may cause this.
continue
# locking not fully working, temporary hack to ensure deduplication
results += [r for r in sub_result if r not in results]
if close_session:
await session.close()
return results
[docs]
def lazy_load(self) -> Iterator[Document]:
"""Lazy load web pages.
When use_async is True, this function will not be lazy,
but it will still work in the expected way, just not lazy."""
visited: Set[str] = set()
if self.use_async:
results = asyncio.run(
self._async_get_child_links_recursive(self.url, visited)
)
return iter(results or [])
else:
return self._get_child_links_recursive(self.url, visited)
_MetadataExtractorType1 = Callable[[str, str], dict]
_MetadataExtractorType2 = Callable[
[str, str, Union[requests.Response, aiohttp.ClientResponse]], dict
]
_MetadataExtractorType = Union[_MetadataExtractorType1, _MetadataExtractorType2]
def _wrap_metadata_extractor(
metadata_extractor: _MetadataExtractorType,
) -> _MetadataExtractorType2:
if len(inspect.signature(metadata_extractor).parameters) == 3:
return cast(_MetadataExtractorType2, metadata_extractor)
else:
def _metadata_extractor_wrapper(
raw_html: str,
url: str,
response: Union[requests.Response, aiohttp.ClientResponse],
) -> dict:
return cast(_MetadataExtractorType1, metadata_extractor)(raw_html, url)
return _metadata_extractor_wrapper
