docs/langchain/libs/community/langchain_community/document_loaders/chromium.py

import asyncio
import logging
from typing import AsyncIterator, Iterator, List, Optional

from langchain_core.documents import Document

from langchain_community.document_loaders.base import BaseLoader
from langchain_community.utils.user_agent import get_user_agent

logger = logging.getLogger(__name__)


class AsyncChromiumLoader(BaseLoader):
    """Scrape HTML pages from URLs using a
    headless instance of the Chromium."""

    def __init__(
        self,
        urls: List[str],
        *,
        headless: bool = True,
        user_agent: Optional[str] = None,
    ):
        """Initialize the loader with a list of URL paths.

        Args:
            urls: A list of URLs to scrape content from.
            headless: Whether to run browser in headless mode.
            user_agent: The user agent to use for the browser

        Raises:
            ImportError: If the required 'playwright' package is not installed.
        """
        self.urls = urls
        self.headless = headless
        self.user_agent = user_agent or get_user_agent()

        try:
            import playwright  # noqa: F401
        except ImportError:
            raise ImportError(
                "playwright is required for AsyncChromiumLoader. "
                "Please install it with `pip install playwright`."
            )

    async def ascrape_playwright(self, url: str) -> str:
        """
        Asynchronously scrape the content of a given URL using Playwright's async API.

        Args:
            url (str): The URL to scrape.

        Returns:
            str: The scraped HTML content or an error message if an exception occurs.

        """
        from playwright.async_api import async_playwright

        logger.info("Starting scraping...")
        results = ""
        async with async_playwright() as p:
            browser = await p.chromium.launch(headless=self.headless)
            try:
                page = await browser.new_page(user_agent=self.user_agent)
                await page.goto(url)
                results = await page.content()  # Simply get the HTML content
                logger.info("Content scraped")
            except Exception as e:
                results = f"Error: {e}"
            await browser.close()
        return results

    def lazy_load(self) -> Iterator[Document]:
        """
        Lazily load text content from the provided URLs.

        This method yields Documents one at a time as they're scraped,
        instead of waiting to scrape all URLs before returning.

        Yields:
            Document: The scraped content encapsulated within a Document object.

        """
        for url in self.urls:
            html_content = asyncio.run(self.ascrape_playwright(url))
            metadata = {"source": url}
            yield Document(page_content=html_content, metadata=metadata)

    async def alazy_load(self) -> AsyncIterator[Document]:
        """
        Asynchronously load text content from the provided URLs.

        This method leverages asyncio to initiate the scraping of all provided URLs
        simultaneously. It improves performance by utilizing concurrent asynchronous
        requests. Each Document is yielded as soon as its content is available,
        encapsulating the scraped content.

        Yields:
            Document: A Document object containing the scraped content, along with its
            source URL as metadata.
        """
        tasks = [self.ascrape_playwright(url) for url in self.urls]
        results = await asyncio.gather(*tasks)
        for url, content in zip(self.urls, results):
            metadata = {"source": url}
            yield Document(page_content=content, metadata=metadata)