mirror of https://github.com/hwchase17/langchain
You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
268 lines
9.9 KiB
Python
268 lines
9.9 KiB
Python
9 months ago
|
"""Web base loader class."""
|
||
|
import asyncio
|
||
|
import logging
|
||
|
import warnings
|
||
|
from typing import Any, Dict, Iterator, List, Optional, Sequence, Union
|
||
|
|
||
|
import aiohttp
|
||
|
import requests
|
||
|
from langchain_core.documents import Document
|
||
|
|
||
|
from langchain_community.document_loaders.base import BaseLoader
|
||
|
|
||
|
logger = logging.getLogger(__name__)
|
||
|
|
||
|
default_header_template = {
|
||
|
"User-Agent": "",
|
||
|
"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*"
|
||
|
";q=0.8",
|
||
|
"Accept-Language": "en-US,en;q=0.5",
|
||
|
"Referer": "https://www.google.com/",
|
||
|
"DNT": "1",
|
||
|
"Connection": "keep-alive",
|
||
|
"Upgrade-Insecure-Requests": "1",
|
||
|
}
|
||
|
|
||
|
|
||
|
def _build_metadata(soup: Any, url: str) -> dict:
|
||
|
"""Build metadata from BeautifulSoup output."""
|
||
|
metadata = {"source": url}
|
||
|
if title := soup.find("title"):
|
||
|
metadata["title"] = title.get_text()
|
||
|
if description := soup.find("meta", attrs={"name": "description"}):
|
||
|
metadata["description"] = description.get("content", "No description found.")
|
||
|
if html := soup.find("html"):
|
||
|
metadata["language"] = html.get("lang", "No language found.")
|
||
|
return metadata
|
||
|
|
||
|
|
||
|
class WebBaseLoader(BaseLoader):
|
||
|
"""Load HTML pages using `urllib` and parse them with `BeautifulSoup'."""
|
||
|
|
||
|
def __init__(
|
||
|
self,
|
||
|
web_path: Union[str, Sequence[str]] = "",
|
||
|
header_template: Optional[dict] = None,
|
||
|
verify_ssl: bool = True,
|
||
|
proxies: Optional[dict] = None,
|
||
|
continue_on_failure: bool = False,
|
||
|
autoset_encoding: bool = True,
|
||
|
encoding: Optional[str] = None,
|
||
|
web_paths: Sequence[str] = (),
|
||
|
requests_per_second: int = 2,
|
||
|
default_parser: str = "html.parser",
|
||
|
requests_kwargs: Optional[Dict[str, Any]] = None,
|
||
|
raise_for_status: bool = False,
|
||
|
bs_get_text_kwargs: Optional[Dict[str, Any]] = None,
|
||
|
bs_kwargs: Optional[Dict[str, Any]] = None,
|
||
|
session: Any = None,
|
||
|
) -> None:
|
||
|
"""Initialize loader.
|
||
|
|
||
|
Args:
|
||
|
web_paths: Web paths to load from.
|
||
|
requests_per_second: Max number of concurrent requests to make.
|
||
|
default_parser: Default parser to use for BeautifulSoup.
|
||
|
requests_kwargs: kwargs for requests
|
||
|
raise_for_status: Raise an exception if http status code denotes an error.
|
||
|
bs_get_text_kwargs: kwargs for beatifulsoup4 get_text
|
||
|
bs_kwargs: kwargs for beatifulsoup4 web page parsing
|
||
|
"""
|
||
|
# web_path kept for backwards-compatibility.
|
||
|
if web_path and web_paths:
|
||
|
raise ValueError(
|
||
|
"Received web_path and web_paths. Only one can be specified. "
|
||
|
"web_path is deprecated, web_paths should be used."
|
||
|
)
|
||
|
if web_paths:
|
||
|
self.web_paths = list(web_paths)
|
||
|
elif isinstance(web_path, str):
|
||
|
self.web_paths = [web_path]
|
||
|
elif isinstance(web_path, Sequence):
|
||
|
self.web_paths = list(web_path)
|
||
|
else:
|
||
|
raise TypeError(
|
||
|
f"web_path must be str or Sequence[str] got ({type(web_path)}) or"
|
||
|
f" web_paths must be Sequence[str] got ({type(web_paths)})"
|
||
|
)
|
||
|
self.requests_per_second = requests_per_second
|
||
|
self.default_parser = default_parser
|
||
|
self.requests_kwargs = requests_kwargs or {}
|
||
|
self.raise_for_status = raise_for_status
|
||
|
self.bs_get_text_kwargs = bs_get_text_kwargs or {}
|
||
|
self.bs_kwargs = bs_kwargs or {}
|
||
|
if session:
|
||
|
self.session = session
|
||
|
else:
|
||
|
session = requests.Session()
|
||
|
header_template = header_template or default_header_template.copy()
|
||
|
if not header_template.get("User-Agent"):
|
||
|
try:
|
||
|
from fake_useragent import UserAgent
|
||
|
|
||
|
header_template["User-Agent"] = UserAgent().random
|
||
|
except ImportError:
|
||
|
logger.info(
|
||
|
"fake_useragent not found, using default user agent."
|
||
|
"To get a realistic header for requests, "
|
||
|
"`pip install fake_useragent`."
|
||
|
)
|
||
|
session.headers = dict(header_template)
|
||
|
session.verify = verify_ssl
|
||
|
if proxies:
|
||
|
session.proxies.update(proxies)
|
||
|
self.session = session
|
||
|
self.continue_on_failure = continue_on_failure
|
||
|
self.autoset_encoding = autoset_encoding
|
||
|
self.encoding = encoding
|
||
|
|
||
|
@property
|
||
|
def web_path(self) -> str:
|
||
|
if len(self.web_paths) > 1:
|
||
|
raise ValueError("Multiple webpaths found.")
|
||
|
return self.web_paths[0]
|
||
|
|
||
|
async def _fetch(
|
||
|
self, url: str, retries: int = 3, cooldown: int = 2, backoff: float = 1.5
|
||
|
) -> str:
|
||
|
async with aiohttp.ClientSession() as session:
|
||
|
for i in range(retries):
|
||
|
try:
|
||
|
async with session.get(
|
||
|
url,
|
||
|
headers=self.session.headers,
|
||
|
ssl=None if self.session.verify else False,
|
||
|
) as response:
|
||
|
return await response.text()
|
||
|
except aiohttp.ClientConnectionError as e:
|
||
|
if i == retries - 1:
|
||
|
raise
|
||
|
else:
|
||
|
logger.warning(
|
||
|
f"Error fetching {url} with attempt "
|
||
|
f"{i + 1}/{retries}: {e}. Retrying..."
|
||
|
)
|
||
|
await asyncio.sleep(cooldown * backoff**i)
|
||
|
raise ValueError("retry count exceeded")
|
||
|
|
||
|
async def _fetch_with_rate_limit(
|
||
|
self, url: str, semaphore: asyncio.Semaphore
|
||
|
) -> str:
|
||
|
async with semaphore:
|
||
|
try:
|
||
|
return await self._fetch(url)
|
||
|
except Exception as e:
|
||
|
if self.continue_on_failure:
|
||
|
logger.warning(
|
||
|
f"Error fetching {url}, skipping due to"
|
||
|
f" continue_on_failure=True"
|
||
|
)
|
||
|
return ""
|
||
|
logger.exception(
|
||
|
f"Error fetching {url} and aborting, use continue_on_failure=True "
|
||
|
"to continue loading urls after encountering an error."
|
||
|
)
|
||
|
raise e
|
||
|
|
||
|
async def fetch_all(self, urls: List[str]) -> Any:
|
||
|
"""Fetch all urls concurrently with rate limiting."""
|
||
|
semaphore = asyncio.Semaphore(self.requests_per_second)
|
||
|
tasks = []
|
||
|
for url in urls:
|
||
|
task = asyncio.ensure_future(self._fetch_with_rate_limit(url, semaphore))
|
||
|
tasks.append(task)
|
||
|
try:
|
||
|
from tqdm.asyncio import tqdm_asyncio
|
||
|
|
||
|
return await tqdm_asyncio.gather(
|
||
|
*tasks, desc="Fetching pages", ascii=True, mininterval=1
|
||
|
)
|
||
|
except ImportError:
|
||
|
warnings.warn("For better logging of progress, `pip install tqdm`")
|
||
|
return await asyncio.gather(*tasks)
|
||
|
|
||
|
@staticmethod
|
||
|
def _check_parser(parser: str) -> None:
|
||
|
"""Check that parser is valid for bs4."""
|
||
|
valid_parsers = ["html.parser", "lxml", "xml", "lxml-xml", "html5lib"]
|
||
|
if parser not in valid_parsers:
|
||
|
raise ValueError(
|
||
|
"`parser` must be one of " + ", ".join(valid_parsers) + "."
|
||
|
)
|
||
|
|
||
|
def scrape_all(self, urls: List[str], parser: Union[str, None] = None) -> List[Any]:
|
||
|
"""Fetch all urls, then return soups for all results."""
|
||
|
from bs4 import BeautifulSoup
|
||
|
|
||
|
results = asyncio.run(self.fetch_all(urls))
|
||
|
final_results = []
|
||
|
for i, result in enumerate(results):
|
||
|
url = urls[i]
|
||
|
if parser is None:
|
||
|
if url.endswith(".xml"):
|
||
|
parser = "xml"
|
||
|
else:
|
||
|
parser = self.default_parser
|
||
|
self._check_parser(parser)
|
||
|
final_results.append(BeautifulSoup(result, parser, **self.bs_kwargs))
|
||
|
|
||
|
return final_results
|
||
|
|
||
|
def _scrape(
|
||
|
self,
|
||
|
url: str,
|
||
|
parser: Union[str, None] = None,
|
||
|
bs_kwargs: Optional[dict] = None,
|
||
|
) -> Any:
|
||
|
from bs4 import BeautifulSoup
|
||
|
|
||
|
if parser is None:
|
||
|
if url.endswith(".xml"):
|
||
|
parser = "xml"
|
||
|
else:
|
||
|
parser = self.default_parser
|
||
|
|
||
|
self._check_parser(parser)
|
||
|
|
||
|
html_doc = self.session.get(url, **self.requests_kwargs)
|
||
|
if self.raise_for_status:
|
||
|
html_doc.raise_for_status()
|
||
|
|
||
|
if self.encoding is not None:
|
||
|
html_doc.encoding = self.encoding
|
||
|
elif self.autoset_encoding:
|
||
|
html_doc.encoding = html_doc.apparent_encoding
|
||
|
return BeautifulSoup(html_doc.text, parser, **(bs_kwargs or {}))
|
||
|
|
||
|
def scrape(self, parser: Union[str, None] = None) -> Any:
|
||
|
"""Scrape data from webpage and return it in BeautifulSoup format."""
|
||
|
|
||
|
if parser is None:
|
||
|
parser = self.default_parser
|
||
|
|
||
|
return self._scrape(self.web_path, parser=parser, bs_kwargs=self.bs_kwargs)
|
||
|
|
||
|
def lazy_load(self) -> Iterator[Document]:
|
||
|
"""Lazy load text from the url(s) in web_path."""
|
||
|
for path in self.web_paths:
|
||
|
soup = self._scrape(path, bs_kwargs=self.bs_kwargs)
|
||
|
text = soup.get_text(**self.bs_get_text_kwargs)
|
||
|
metadata = _build_metadata(soup, path)
|
||
|
yield Document(page_content=text, metadata=metadata)
|
||
|
|
||
|
def load(self) -> List[Document]:
|
||
|
"""Load text from the url(s) in web_path."""
|
||
|
return list(self.lazy_load())
|
||
|
|
||
|
def aload(self) -> List[Document]:
|
||
|
"""Load text from the urls in web_path async into Documents."""
|
||
|
|
||
|
results = self.scrape_all(self.web_paths)
|
||
|
docs = []
|
||
|
for path, soup in zip(self.web_paths, results):
|
||
|
text = soup.get_text(**self.bs_get_text_kwargs)
|
||
|
metadata = _build_metadata(soup, path)
|
||
|
docs.append(Document(page_content=text, metadata=metadata))
|
||
|
|
||
|
return docs
|