Add get_bsky_post_by_url example (#424)

Co-authored-by: Ilya (Marshal) <[email protected]>

examples/advanced_usage/get_bsky_post_by_url.py

@@ -0,0 +1,57 @@
+from typing import Optional
+
+from atproto import Client, IdResolver, models
+
+
+def fetch_posts(client: Client, resolver: IdResolver, url: str) -> Optional[models.AppBskyFeedPost.Record]:
+    """Fetch a post using its Bluesky URL.
+
+    Args:
+        client (Client): Authenticated Atproto client.
+        resolver (IdResolver): Resolver instance for DID lookup.
+        url (str): URL of the Bluesky post.
+    Returns:
+        :obj:`models.AppBskyFeedPost.Record`: Post if found, otherwise None.
+    """
+    try:
+        # Extract the handle and post rkey from the URL
+        url_parts = url.split('/')
+        handle = url_parts[4]  # Username in the URL
+        post_rkey = url_parts[6]  # Post Record Key in the URL
+
+        # Resolve the DID for the username
+        did = resolver.handle.resolve(handle)
+        if not did:
+            print(f'Could not resolve DID for handle "{handle}".')
+            return None
+
+        # Fetch the post record
+        return client.get_post(post_rkey, did).value
+    except (ValueError, KeyError) as e:
+        print(f'Error fetching post for URL {url}: {e}')
+        return None
+
+
+def main() -> None:
+    # Initialize a client and authenticate
+    client = Client()
+    client.login('my-handle', 'my-password')
+
+    # Initialize IdResolver for DID resolution
+    resolver = IdResolver()
+
+    # Define the URL of the post to fetch
+    bsky_post_url = 'https://bsky.app/profile/test.marshal.dev/post/3laqsdrwwgc24'
+
+    # Fetch the post
+    post_record = fetch_posts(client, resolver, bsky_post_url)
+
+    # Display the post details
+    if post_record:
+        print(f'Post content: {post_record.text}')
+    else:
+        print('Post could not be fetched.')
+
+
+if __name__ == '__main__':
+    main()