self.html is of type str and has no id attribute when using TemplateResponse/TemplateStringResponse

[florian-rabis]

Hi,
I'm having an issue when using TemplateResponse. Apparently, the template is not being translated into a Lona node tree.

The error is not thrown right at the beginning but only when I click the button. However, my open_dialog method is not executed.

I get this tracestack:

MainThread                     ERROR    10:02:32.873117 aiohttp.server Error handling request
  Traceback (most recent call last):
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\aiohttp\web_protocol.py", line 456, in _handle_request
      resp = await request_handler(request)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\aiohttp\web_app.py", line 537, in _handle
      resp = await handler(request)
             ^^^^^^^^^^^^^^^^^^^^^^
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\lona\server.py", line 649, in _shielded_handle_http_request
      return await asyncio.shield(self._handle_http_request(request))
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\lona\server.py", line 597, in _handle_http_request
      return await self._handle_websocket_request(http_request)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\lona\server.py", line 508, in _handle_websocket_request
      await self._handle_websocket_message(connection, message)
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\lona\server.py", line 453, in _handle_websocket_message
      await self._middleware_controller.handle_websocket_message(
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\lona\middleware_controller.py", line 206, in handle_websocket_message
      return await self.server.run_function_async(
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "C:\Users\user\AppData\Local\Programs\Python\Python312\Lib\concurrent\futures\thread.py", line 58, in run
      result = self.fn(*self.args, **self.kwargs)
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\lona\server.py", line 711, in _function
      return function(*args, **kwargs)
             ^^^^^^^^^^^^^^^^^^^^^^^^^
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\lona\middleware_controller.py", line 111, in _run_middlewares_sync
      return_value = hook(data)
                     ^^^^^^^^^^
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\lona\middlewares\lona_messages.py", line 32, in handle_websocket_message
      data.server._view_runtime_controller.handle_lona_message(
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\lona\view_runtime_controller.py", line 321, in handle_lona_message
      self.handle_input_event_message(
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\lona\view_runtime_controller.py", line 121, in handle_input_event_message
      view_runtime.handle_input_event(
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\lona\view_runtime.py", line 715, in handle_input_event
      input_event = InputEvent(
                    ^^^^^^^^^^^
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\lona\events\input_event.py", line 64, in __init__
      self.nodes = document.get_node(node_id=self.node_info[0])
                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    File "C:\Users\user\Desktop\data\Workspace\python-lona-app\.venv\Lib\site-packages\lona\html\document.py", line 40, in get_node
      if self.html.id == node_id:
         ^^^^^^^^^^^^
  AttributeError: 'str' object has no attribute 'id'

Here is my code:

views.py:

class IndexView(View):
    def open_dialog(self, input_event):
        print("Hello World")

    def handle_request(self, request):
        self.catalog_button = Button("Catalog", handle_click=self.open_dialog)
        self.menu.nodes = [
            self.catalog_button
        ]

        return TemplateResponse(
            "base.html", 
            {
                "menu": self.menu,
                "content": self.content
            }
        )

templates/base.html:

<header>
    <h1>Apptitle</h1>
</header>

<nav>
    {{ menu }}
</nav>

<main>
    {{ content }}
</main>

<footer></footer>

I use the picocss frontend template. When I just return all as HTML-Node then everything works fine.

When I modify the document.py like this, it seems to work correctly:

document.py:

...

def get_node(self, node_id):
    node = None
    nodes = []

    with self.lock:
        if type(self.html) is str:
            self.html = html.parse_html(self.html)[0]
        
        if self.html.id == node_id:
            node = self.html

...

Best regards

[fscherf]

hi @florian-rabis!

Template responses are not intended to be used like this. You use either Lona nodes or a template in a view, but not both.

[florian-rabis]

Thank you for the explanation. OK, I’ll need to rethink my approach a bit. I thought it would be more efficient to create as few nodes as possible server-side as Python objects. My idea was to be able to adjust lists or tables more flexibly using templates.

[fscherf]

No problem! Don't hesitate to ask if something remains unclear.

I wouldn't worry too much about that. Lona is designed to handle big trees with a lot of nodes. If you encounter any bottlenecks, let me know.