Source code for langchain_community.document_loaders.async_html

import asyncio
import logging
import warnings
from concurrent.futures import ThreadPoolExecutor
from typing import Any, Dict, Iterator, List, Optional, Union, cast

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


[docs]class AsyncHtmlLoader(BaseLoader): """Load `HTML` asynchronously."""
[docs] def __init__( self, web_path: Union[str, List[str]], header_template: Optional[dict] = None, verify_ssl: Optional[bool] = True, proxies: Optional[dict] = None, autoset_encoding: bool = True, encoding: Optional[str] = None, default_parser: str = "html.parser", requests_per_second: int = 2, requests_kwargs: Optional[Dict[str, Any]] = None, raise_for_status: bool = False, ignore_load_errors: bool = False, ): """Initialize with a webpage path.""" # TODO: Deprecate web_path in favor of web_paths, and remove this # left like this because there are a number of loaders that expect single # urls if isinstance(web_path, str): self.web_paths = [web_path] elif isinstance(web_path, List): self.web_paths = web_path headers = header_template or default_header_template if not headers.get("User-Agent"): try: from fake_useragent import UserAgent headers["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`." ) self.session = requests.Session() self.session.headers = dict(headers) self.session.verify = verify_ssl if proxies: self.session.proxies.update(proxies) 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.autoset_encoding = autoset_encoding self.encoding = encoding self.ignore_load_errors = ignore_load_errors
def _fetch_valid_connection_docs(self, url: str) -> Any: if self.ignore_load_errors: try: return self.session.get(url, **self.requests_kwargs) except Exception as e: warnings.warn(str(e)) return None return self.session.get(url, **self.requests_kwargs) @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( 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._fetch_valid_connection_docs(url) if not getattr(html_doc, "ok", False): return None 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 {})) 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: try: text = await response.text() except UnicodeDecodeError: logger.error(f"Failed to decode content from {url}") text = "" return text except aiohttp.ClientConnectionError as e: if i == retries - 1 and self.ignore_load_errors: logger.warning(f"Error fetching {url} after {retries} retries.") return "" elif 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: return await self._fetch(url)
[docs] 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)
[docs] def lazy_load(self) -> Iterator[Document]: """Lazy load text from the url(s) in web_path.""" for doc in self.load(): yield doc
[docs] def load(self) -> List[Document]: """Load text from the url(s) in web_path.""" try: # Raises RuntimeError if there is no current event loop. asyncio.get_running_loop() # If there is a current event loop, we need to run the async code # in a separate loop, in a separate thread. with ThreadPoolExecutor(max_workers=1) as executor: future = executor.submit(asyncio.run, self.fetch_all(self.web_paths)) results = future.result() except RuntimeError: results = asyncio.run(self.fetch_all(self.web_paths)) docs = [] for i, text in enumerate(cast(List[str], results)): soup = self._scrape(self.web_paths[i]) if not soup: continue metadata = _build_metadata(soup, self.web_paths[i]) docs.append(Document(page_content=text, metadata=metadata)) return docs