Session Management
Session management in Crawl4AI is a powerful feature that allows you to maintain state across multiple requests, making it particularly suitable for handling complex multi-step crawling tasks. It enables you to reuse the same browser tab (or page object) across sequential actions and crawls, which is beneficial for:
- Performing JavaScript actions before and after crawling.
- Executing multiple sequential crawls faster without needing to reopen tabs or allocate memory repeatedly.
Note: This feature is designed for sequential workflows and is not suitable for parallel operations.
Basic Session Usage
Use BrowserConfig and CrawlerRunConfig to maintain state with a session_id:
from crawl4ai.async_configs import BrowserConfig, CrawlerRunConfig
async with AsyncWebCrawler() as crawler:
session_id = "my_session"
# Define configurations
config1 = CrawlerRunConfig(
url="https://example.com/page1", session_id=session_id
)
config2 = CrawlerRunConfig(
url="https://example.com/page2", session_id=session_id
)
# First request
result1 = await crawler.arun(config=config1)
# Subsequent request using the same session
result2 = await crawler.arun(config=config2)
# Clean up when done
await crawler.crawler_strategy.kill_session(session_id)
Dynamic Content with Sessions
Here's an example of crawling GitHub commits across multiple pages while preserving session state:
from crawl4ai.async_configs import CrawlerRunConfig
from crawl4ai import JsonCssExtractionStrategy
from crawl4ai.cache_context import CacheMode
async def crawl_dynamic_content():
url = "https://github.com/microsoft/TypeScript/commits/main"
session_id = "wait_for_session"
all_commits = []
js_next_page = """
const commits = document.querySelectorAll('li[data-testid="commit-row-item"] h4');
if (commits.length > 0) {
window.lastCommit = commits[0].textContent.trim();
}
const button = document.querySelector('a[data-testid="pagination-next-button"]');
if (button) {button.click(); console.log('button clicked') }
"""
wait_for = """() => {
const commits = document.querySelectorAll('li[data-testid="commit-row-item"] h4');
if (commits.length === 0) return false;
const firstCommit = commits[0].textContent.trim();
return firstCommit !== window.lastCommit;
}"""
schema = {
"name": "Commit Extractor",
"baseSelector": "li[data-testid='commit-row-item']",
"fields": [
{
"name": "title",
"selector": "h4 a",
"type": "text",
"transform": "strip",
},
],
}
extraction_strategy = JsonCssExtractionStrategy(schema, verbose=True)
browser_config = BrowserConfig(
verbose=True,
headless=False,
)
async with AsyncWebCrawler(config=browser_config) as crawler:
for page in range(3):
crawler_config = CrawlerRunConfig(
session_id=session_id,
css_selector="li[data-testid='commit-row-item']",
extraction_strategy=extraction_strategy,
js_code=js_next_page if page > 0 else None,
wait_for=wait_for if page > 0 else None,
js_only=page > 0,
cache_mode=CacheMode.BYPASS,
capture_console_messages=True,
)
result = await crawler.arun(url=url, config=crawler_config)
if result.console_messages:
print(f"Page {page + 1} console messages:", result.console_messages)
if result.extracted_content:
# print(f"Page {page + 1} result:", result.extracted_content)
commits = json.loads(result.extracted_content)
all_commits.extend(commits)
print(f"Page {page + 1}: Found {len(commits)} commits")
else:
print(f"Page {page + 1}: No content extracted")
print(f"Successfully crawled {len(all_commits)} commits across 3 pages")
# Clean up session
await crawler.crawler_strategy.kill_session(session_id)
Example 1: Basic Session-Based Crawling
A simple example using session-based crawling:
import asyncio
from crawl4ai.async_configs import BrowserConfig, CrawlerRunConfig
from crawl4ai.cache_context import CacheMode
async def basic_session_crawl():
async with AsyncWebCrawler() as crawler:
session_id = "dynamic_content_session"
url = "https://example.com/dynamic-content"
for page in range(3):
config = CrawlerRunConfig(
url=url,
session_id=session_id,
js_code="document.querySelector('.load-more-button').click();" if page > 0 else None,
css_selector=".content-item",
cache_mode=CacheMode.BYPASS
)
result = await crawler.arun(config=config)
print(f"Page {page + 1}: Found {result.extracted_content.count('.content-item')} items")
await crawler.crawler_strategy.kill_session(session_id)
asyncio.run(basic_session_crawl())
This example shows:
1. Reusing the same session_id across multiple requests.
2. Executing JavaScript to load more content dynamically.
3. Properly closing the session to free resources.
Advanced Technique 1: Custom Execution Hooks
Warning: You might feel confused by the end of the next few examples 😅, so make sure you are comfortable with the order of the parts before you start this.
Use custom hooks to handle complex scenarios, such as waiting for content to load dynamically:
async def advanced_session_crawl_with_hooks():
first_commit = ""
async def on_execution_started(page):
nonlocal first_commit
try:
while True:
await page.wait_for_selector("li.commit-item h4")
commit = await page.query_selector("li.commit-item h4")
commit = await commit.evaluate("(element) => element.textContent").strip()
if commit and commit != first_commit:
first_commit = commit
break
await asyncio.sleep(0.5)
except Exception as e:
print(f"Warning: New content didn't appear: {e}")
async with AsyncWebCrawler() as crawler:
session_id = "commit_session"
url = "https://github.com/example/repo/commits/main"
crawler.crawler_strategy.set_hook("on_execution_started", on_execution_started)
js_next_page = """document.querySelector('a.pagination-next').click();"""
for page in range(3):
config = CrawlerRunConfig(
url=url,
session_id=session_id,
js_code=js_next_page if page > 0 else None,
css_selector="li.commit-item",
js_only=page > 0,
cache_mode=CacheMode.BYPASS
)
result = await crawler.arun(config=config)
print(f"Page {page + 1}: Found {len(result.extracted_content)} commits")
await crawler.crawler_strategy.kill_session(session_id)
asyncio.run(advanced_session_crawl_with_hooks())
This technique ensures new content loads before the next action.
Advanced Technique 2: Integrated JavaScript Execution and Waiting
Combine JavaScript execution and waiting logic for concise handling of dynamic content:
async def integrated_js_and_wait_crawl():
async with AsyncWebCrawler() as crawler:
session_id = "integrated_session"
url = "https://github.com/example/repo/commits/main"
js_next_page_and_wait = """
(async () => {
const getCurrentCommit = () => document.querySelector('li.commit-item h4').textContent.trim();
const initialCommit = getCurrentCommit();
document.querySelector('a.pagination-next').click();
while (getCurrentCommit() === initialCommit) {
await new Promise(resolve => setTimeout(resolve, 100));
}
})();
"""
for page in range(3):
config = CrawlerRunConfig(
url=url,
session_id=session_id,
js_code=js_next_page_and_wait if page > 0 else None,
css_selector="li.commit-item",
js_only=page > 0,
cache_mode=CacheMode.BYPASS
)
result = await crawler.arun(config=config)
print(f"Page {page + 1}: Found {len(result.extracted_content)} commits")
await crawler.crawler_strategy.kill_session(session_id)
asyncio.run(integrated_js_and_wait_crawl())
Common Use Cases for Sessions
1. Authentication Flows: Login and interact with secured pages.
2. Pagination Handling: Navigate through multiple pages.
3. Form Submissions: Fill forms, submit, and process results.
4. Multi-step Processes: Complete workflows that span multiple actions.
5. Dynamic Content Navigation: Handle JavaScript-rendered or event-triggered content.