chore: Add hooks for customizing the LocalSeleniumCrawlerStrategy

crawl4ai/crawler_strategy.py

@@ -10,7 +10,7 @@ import logging
 import base64
 from PIL import Image, ImageDraw, ImageFont
 from io import BytesIO
-from typing import List
+from typing import List, Callable
 import requests
 import os
 from pathlib import Path
@@ -48,6 +48,10 @@ class CrawlerStrategy(ABC):
     @abstractmethod
     def update_user_agent(self, user_agent: str):
         pass
+    
+    @abstractmethod
+    def set_hook(self, hook_type: str, hook: Callable):
+        pass
 
 class CloudCrawlerStrategy(CrawlerStrategy):
     def __init__(self, use_cached_html = False):
@@ -96,6 +100,14 @@ class LocalSeleniumCrawlerStrategy(CrawlerStrategy):
         self.use_cached_html = use_cached_html
         self.js_code = js_code
         self.verbose = kwargs.get("verbose", False)
+        
+        # Hooks
+        self.hooks = {
+            'on_driver_created': None,
+            'before_get_url': None,
+            'after_get_url': None,
+            'before_return_html': None
+        }
 
         # chromedriver_autoinstaller.install()
         import chromedriver_autoinstaller
@@ -103,10 +115,29 @@ class LocalSeleniumCrawlerStrategy(CrawlerStrategy):
         self.service.log_path = "NUL"
         self.driver = webdriver.Chrome(service=self.service, options=self.options)
 
+    def set_hook(self, hook_type: str, hook: Callable):
+        if hook_type in self.hooks:
+            self.hooks[hook_type] = hook
+        else:
+            raise ValueError(f"Invalid hook type: {hook_type}")
+    
+    def execute_hook(self, hook_type: str, *args):
+        hook = self.hooks.get(hook_type)
+        if hook:
+            result = hook(*args)
+            if result is not None:
+                if isinstance(result, webdriver.Chrome):
+                    return result
+                else:
+                    raise TypeError(f"Hook {hook_type} must return an instance of webdriver.Chrome or None.")
+        # If the hook returns None or there is no hook, return self.driver
+        return self.driver
+
     def update_user_agent(self, user_agent: str):
         self.options.add_argument(f"user-agent={user_agent}")
         self.driver.quit()
         self.driver = webdriver.Chrome(service=self.service, options=self.options)
+        self.driver = self.execute_hook('on_driver_created', self.driver)
 
     def crawl(self, url: str) -> str:
         # Create md5 hash of the URL
@@ -120,12 +151,14 @@ class LocalSeleniumCrawlerStrategy(CrawlerStrategy):
                     return f.read()
 
         try:
+            self.driver = self.execute_hook('before_get_url', self.driver)
             if self.verbose:
                 print(f"[LOG] 🕸️ Crawling {url} using LocalSeleniumCrawlerStrategy...")
             self.driver.get(url)
             WebDriverWait(self.driver, 10).until(
                 EC.presence_of_all_elements_located((By.TAG_NAME, "html"))
             )
+            self.driver = self.execute_hook('after_get_url', self.driver)
             
             # Execute JS code if provided
             if self.js_code and type(self.js_code) == str:
@@ -142,6 +175,7 @@ class LocalSeleniumCrawlerStrategy(CrawlerStrategy):
                     )
             
             html = self.driver.page_source
+            self.driver = self.execute_hook('before_return_html', self.driver, html)
             
             # Store in cache
             cache_file_path = os.path.join(Path.home(), ".crawl4ai", "cache", url_hash)

docs/examples/quickstart.py

@@ -192,6 +192,55 @@ def multiple_scrip(crawler):
     cprint("[LOG] 📦 [bold yellow]JavaScript Code (Load More button) result:[/bold yellow]")
     print_result(result)
 
+def using_crawler_hooks(crawler):
+    # Example usage of the hooks for authentication and setting a cookie
+    def on_driver_created(driver):
+        print("[HOOK] on_driver_created")
+        # Example customization: maximize the window
+        driver.maximize_window()
+        return driver
+
+    def before_get_url(driver):
+        print("[HOOK] before_get_url")
+        # Example customization: logging in to a hypothetical website
+        driver.get('https://example.com/login')
+        WebDriverWait(driver, 10).until(
+            EC.presence_of_element_located((By.NAME, 'username'))
+        )
+        driver.find_element(By.NAME, 'username').send_keys('testuser')
+        driver.find_element(By.NAME, 'password').send_keys('password123')
+        driver.find_element(By.NAME, 'login').click()
+        WebDriverWait(driver, 10).until(
+            EC.presence_of_element_located((By.ID, 'welcome'))
+        )
+        # Add a custom cookie
+        driver.add_cookie({'name': 'test_cookie', 'value': 'cookie_value'})
+        return driver
+
+    def after_get_url(driver):
+        print("[HOOK] after_get_url")
+        # Example customization: log the URL
+        print(driver.current_url)
+        return driver
+
+    def before_return_html(driver, html):
+        print("[HOOK] before_return_html")
+        # Example customization: modify the HTML (for demonstration purposes)
+        modified_html = html.replace('Example Domain', 'Test Domain')
+        return driver, modified_html    
+    
+    cprint("\n🔗 [bold cyan]Using Crawler Hooks: Let's see how we can customize the crawler using hooks![/bold cyan]", True)
+    
+    crawler.set_hook('on_driver_created', on_driver_created)
+    crawler.set_hook('before_get_url', before_get_url)
+    crawler.set_hook('after_get_url', after_get_url)
+    crawler.set_hook('before_return_html', before_return_html)
+    
+    result = crawler.run(url="https://example.com")
+    
+    cprint("[LOG] 📦 [bold yellow]Crawler Hooks result:[/bold yellow]")
+    print_result(result= result)
+
 def main():
     cprint("🌟 [bold green]Welcome to the Crawl4ai Quickstart Guide! Let's dive into some web crawling fun! 🌐[/bold green]")
     cprint("⛳️ [bold cyan]First Step: Create an instance of WebCrawler and call the `warmup()` function.[/bold cyan]")