Upgrade examples to langchain 1.0 (zauberzeug#5304)

### Motivation

Pipeline's red due to langchain 1.0 incompatibilities. 

Error line: `ModuleNotFoundError: No module named
'langchain.callbacks'`, since they moved it in 1.0.

### Implementation

1. Do not install langchain in "install packages to run the examples".
Installed in test_startup.sh anyways.
2. Bump the version to avoid installing too old langchain
3. Change the code (Falko's work)

### Progress

- [x] I chose a meaningful title that completes the sentence: "If
applied, this PR will..."
- [x] The implementation is complete.
- [x] Pytests have been added (or are not necessary).
- [x] Documentation has been added (or is not necessary).

https://github.com/evnchn/nicegui/actions/runs/18641263733

Of course it is more than welcome to make langchain 1.0 compatible, but
I don't have OpenAI access...

---------

Co-authored-by: Falko Schindler <[email protected]>

Author: evnchn

.github/workflows/test.yml

@@ -60,7 +60,7 @@ jobs:
         run: |
           set -x
           # install packages to run the examples
-          poetry run pip install opencv-python opencv-contrib-python-headless httpx isort replicate langchain openai simpy tortoise-orm
+          poetry run pip install opencv-python opencv-contrib-python-headless httpx isort replicate openai simpy tortoise-orm
       - name: test startup
         run: poetry run ./test_startup.sh
       - name: restore dependencies for effective caching

examples/chat_with_ai/log_callback_handler.py

@@ -1,15 +1,13 @@
 #!/usr/bin/env python3
 from html_sanitizer import Sanitizer
 from langchain_openai import ChatOpenAI
-from log_callback_handler import NiceGuiLogElementCallbackHandler
 
 from nicegui import ui
 
 OPENAI_API_KEY = 'not-set'  # TODO: set your OpenAI API key here
 
 
-@ui.page('/')
-def main():
+def root():
     llm = ChatOpenAI(model_name='gpt-4o-mini', streaming=True, openai_api_key=OPENAI_API_KEY)
 
     async def send() -> None:
@@ -22,27 +20,15 @@ async def send() -> None:
             spinner = ui.spinner(type='dots')
 
         response = ''
-        async for chunk in llm.astream(question, config={'callbacks': [NiceGuiLogElementCallbackHandler(log)]}):
+        async for chunk in llm.astream(question):
             response += chunk.content
             response_message.clear()
             with response_message:
                 ui.html(response, sanitize=Sanitizer().sanitize)
             ui.run_javascript('window.scrollTo(0, document.body.scrollHeight)')
         message_container.remove(spinner)
 
-    ui.add_css(r'a:link, a:visited {color: inherit !important; text-decoration: none; font-weight: 500}')
-
-    # the queries below are used to expand the contend down to the footer (content can then use flex-grow to expand)
-    ui.query('.q-page').classes('flex')
-    ui.query('.nicegui-content').classes('w-full')
-
-    with ui.tabs().classes('w-full') as tabs:
-        chat_tab = ui.tab('Chat')
-        logs_tab = ui.tab('Logs')
-    with ui.tab_panels(tabs, value=chat_tab).classes('w-full max-w-2xl mx-auto flex-grow items-stretch'):
-        message_container = ui.tab_panel(chat_tab).classes('items-stretch')
-        with ui.tab_panel(logs_tab):
-            log = ui.log().classes('w-full h-full')
+    message_container = ui.column().classes('w-full max-w-2xl mx-auto flex-grow items-stretch')
 
     with ui.footer().classes('bg-white'), ui.column().classes('w-full max-w-3xl mx-auto my-6'):
         with ui.row().classes('w-full no-wrap items-center'):
@@ -51,7 +37,8 @@ async def send() -> None:
             text = ui.input(placeholder=placeholder).props('rounded outlined input-class=mx-3') \
                 .classes('w-full self-center').on('keydown.enter', send)
         ui.markdown('simple chat app built with [NiceGUI](https://nicegui.io)') \
-            .classes('text-xs self-end mr-8 m-[-1em] text-primary')
+            .classes('text-xs self-end mr-8 m-[-1em] text-primary') \
+            .classes('[&_a]:text-inherit [&_a]:no-underline [&_a]:font-medium')
 
 
-ui.run(title='Chat with GPT-3 (example)')
+ui.run(root, title='Chat with GPT-4o-mini')

examples/chat_with_ai/main.py

@@ -1,5 +1,3 @@
 html-sanitizer>=2.6.0
-langchain>=0.2
-langchain-community
-langchain_openai
+langchain_openai>=0.3
 nicegui>=3.0