mirror of
https://github.com/Mintplex-Labs/langchain-python.git
synced 2026-07-19 21:33:31 -04:00
Tim Asp
3ca1a387c2
Proxies are helpful, especially when you start querying against more anti-bot websites. [Proxy services](https://developers.oxylabs.io/advanced-proxy-solutions/web-unblocker/making-requests) (of which there are many) and `requests` make it easy to rotate IPs to prevent banning by just passing along a simple dict to `requests`. CC @rlancemartin, @eyurtsev
236 lines
8.0 KiB
Python
236 lines
8.0 KiB
Python
"""Web base loader class."""
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import asyncio
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import logging
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import warnings
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from typing import Any, Dict, Iterator, List, Optional, Union
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import aiohttp
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import requests
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from langchain.docstore.document import Document
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from langchain.document_loaders.base import BaseLoader
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logger = logging.getLogger(__name__)
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default_header_template = {
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"User-Agent": "",
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"Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*"
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";q=0.8",
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"Accept-Language": "en-US,en;q=0.5",
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"Referer": "https://www.google.com/",
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"DNT": "1",
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"Connection": "keep-alive",
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"Upgrade-Insecure-Requests": "1",
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}
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def _build_metadata(soup: Any, url: str) -> dict:
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"""Build metadata from BeautifulSoup output."""
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metadata = {"source": url}
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if title := soup.find("title"):
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metadata["title"] = title.get_text()
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if description := soup.find("meta", attrs={"name": "description"}):
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metadata["description"] = description.get("content", None)
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if html := soup.find("html"):
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metadata["language"] = html.get("lang", None)
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return metadata
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class WebBaseLoader(BaseLoader):
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"""Loader that uses urllib and beautiful soup to load webpages."""
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web_paths: List[str]
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requests_per_second: int = 2
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"""Max number of concurrent requests to make."""
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default_parser: str = "html.parser"
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"""Default parser to use for BeautifulSoup."""
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requests_kwargs: Dict[str, Any] = {}
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"""kwargs for requests"""
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raise_for_status: bool = False
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"""Raise an exception if http status code denotes an error."""
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bs_get_text_kwargs: Dict[str, Any] = {}
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"""kwargs for beatifulsoup4 get_text"""
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def __init__(
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self,
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web_path: Union[str, List[str]],
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header_template: Optional[dict] = None,
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verify: Optional[bool] = True,
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proxies: Optional[dict] = None,
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):
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"""Initialize with webpage path."""
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# TODO: Deprecate web_path in favor of web_paths, and remove this
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# left like this because there are a number of loaders that expect single
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# urls
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if isinstance(web_path, str):
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self.web_paths = [web_path]
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elif isinstance(web_path, List):
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self.web_paths = web_path
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self.session = requests.Session()
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try:
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import bs4 # noqa:F401
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except ImportError:
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raise ValueError(
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"bs4 package not found, please install it with " "`pip install bs4`"
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)
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# Choose to verify
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self.verify = verify
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headers = header_template or default_header_template
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if not headers.get("User-Agent"):
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try:
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from fake_useragent import UserAgent
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headers["User-Agent"] = UserAgent().random
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except ImportError:
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logger.info(
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"fake_useragent not found, using default user agent."
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"To get a realistic header for requests, "
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"`pip install fake_useragent`."
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)
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self.session.headers = dict(headers)
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if proxies:
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self.session.proxies.update(proxies)
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@property
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def web_path(self) -> str:
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if len(self.web_paths) > 1:
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raise ValueError("Multiple webpaths found.")
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return self.web_paths[0]
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async def _fetch(
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self, url: str, retries: int = 3, cooldown: int = 2, backoff: float = 1.5
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) -> str:
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# For SiteMap SSL verification
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if not self.requests_kwargs.get("verify", True):
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connector = aiohttp.TCPConnector(ssl=False)
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else:
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connector = None
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async with aiohttp.ClientSession(connector=connector) as session:
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for i in range(retries):
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try:
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async with session.get(
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url, headers=self.session.headers, verify=self.verify
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) as response:
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return await response.text()
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except aiohttp.ClientConnectionError as e:
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if i == retries - 1:
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raise
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else:
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logger.warning(
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f"Error fetching {url} with attempt "
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f"{i + 1}/{retries}: {e}. Retrying..."
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)
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await asyncio.sleep(cooldown * backoff**i)
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raise ValueError("retry count exceeded")
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async def _fetch_with_rate_limit(
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self, url: str, semaphore: asyncio.Semaphore
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) -> str:
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async with semaphore:
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return await self._fetch(url)
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async def fetch_all(self, urls: List[str]) -> Any:
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"""Fetch all urls concurrently with rate limiting."""
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semaphore = asyncio.Semaphore(self.requests_per_second)
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tasks = []
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for url in urls:
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task = asyncio.ensure_future(self._fetch_with_rate_limit(url, semaphore))
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tasks.append(task)
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try:
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from tqdm.asyncio import tqdm_asyncio
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return await tqdm_asyncio.gather(
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*tasks, desc="Fetching pages", ascii=True, mininterval=1
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)
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except ImportError:
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warnings.warn("For better logging of progress, `pip install tqdm`")
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return await asyncio.gather(*tasks)
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@staticmethod
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def _check_parser(parser: str) -> None:
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"""Check that parser is valid for bs4."""
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valid_parsers = ["html.parser", "lxml", "xml", "lxml-xml", "html5lib"]
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if parser not in valid_parsers:
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raise ValueError(
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"`parser` must be one of " + ", ".join(valid_parsers) + "."
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)
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def scrape_all(self, urls: List[str], parser: Union[str, None] = None) -> List[Any]:
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"""Fetch all urls, then return soups for all results."""
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from bs4 import BeautifulSoup
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results = asyncio.run(self.fetch_all(urls))
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final_results = []
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for i, result in enumerate(results):
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url = urls[i]
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if parser is None:
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if url.endswith(".xml"):
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parser = "xml"
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else:
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parser = self.default_parser
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self._check_parser(parser)
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final_results.append(BeautifulSoup(result, parser))
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return final_results
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def _scrape(self, url: str, parser: Union[str, None] = None) -> Any:
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from bs4 import BeautifulSoup
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if parser is None:
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if url.endswith(".xml"):
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parser = "xml"
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else:
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parser = self.default_parser
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self._check_parser(parser)
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html_doc = self.session.get(url, verify=self.verify, **self.requests_kwargs)
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if self.raise_for_status:
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html_doc.raise_for_status()
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html_doc.encoding = html_doc.apparent_encoding
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return BeautifulSoup(html_doc.text, parser)
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def scrape(self, parser: Union[str, None] = None) -> Any:
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"""Scrape data from webpage and return it in BeautifulSoup format."""
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if parser is None:
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parser = self.default_parser
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return self._scrape(self.web_path, parser)
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def lazy_load(self) -> Iterator[Document]:
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"""Lazy load text from the url(s) in web_path."""
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for path in self.web_paths:
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soup = self._scrape(path)
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text = soup.get_text(**self.bs_get_text_kwargs)
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metadata = _build_metadata(soup, path)
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yield Document(page_content=text, metadata=metadata)
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def load(self) -> List[Document]:
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"""Load text from the url(s) in web_path."""
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return list(self.lazy_load())
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def aload(self) -> List[Document]:
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"""Load text from the urls in web_path async into Documents."""
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results = self.scrape_all(self.web_paths)
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docs = []
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for i in range(len(results)):
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soup = results[i]
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text = soup.get_text(**self.bs_get_text_kwargs)
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metadata = _build_metadata(soup, self.web_paths[i])
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docs.append(Document(page_content=text, metadata=metadata))
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return docs
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