Intermittent TypeError related to lru_cache?

[triopter]

Hello! I'm intermittently getting a 500 from the backend when calling a component method. Here's an example payload:

{"id":"Ck9kDpm5:table-row:159","data":{"row":{"table":37,"title":"Memory financial give.","order":720,"pk":159}},"checksum":"5YxwpjTk","actionQueue":[{"type":"callMethod","payload":{"name":"print_saving(122)"},"partials":[]}],"epoch":1629327423683,"hash":"3ffoSeN3"}

And a sample traceback:

Field 'id' expected a number but got <TableCell: Certain usually speak pressure gun image manager. Whose prevent state indicate society beautiful decide. Clearly financial shake seem director.>.

Request Method: POST
Request URL: http://localhost:8000/unicorn/message/table-row
Django Version: 3.2.6
Python Version: 3.8.2
Server time: Wed, 18 Aug 2021 22:57:04 +0000
Installed Applications:
['django.contrib.admin',
 'django.contrib.auth',
 'django.contrib.contenttypes',
 'django.contrib.sessions',
 'django.contrib.messages',
 'django.contrib.staticfiles',
 'tables',
 'django_unicorn',
 'django_seed']
Installed Middleware:
['django.middleware.security.SecurityMiddleware',
 'django.contrib.sessions.middleware.SessionMiddleware',
 'django.middleware.common.CommonMiddleware',
 'django.middleware.csrf.CsrfViewMiddleware',
 'django.contrib.auth.middleware.AuthenticationMiddleware',
 'django.contrib.messages.middleware.MessageMiddleware',
 'django.middleware.clickjacking.XFrameOptionsMiddleware']


Traceback (most recent call last):
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/db/models/fields/__init__.py", line 1823, in get_prep_value
    return int(value)

The above exception (int() argument must be a string, a bytes-like object or a number, not 'TableCell') was the direct cause of the following exception:
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/core/handlers/exception.py", line 47, in inner
    response = get_response(request)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/core/handlers/base.py", line 181, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "<decorator-gen-26>", line 2, in message
    <source code not available>
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django_unicorn/decorators.py", line 66, in timed
    result = func(*args, **kwargs)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django_unicorn/views/__init__.py", line 42, in wrapped_view
    return view_func(*args, **kwargs)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/utils/decorators.py", line 130, in _wrapped_view
    response = view_func(request, *args, **kwargs)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/views/decorators/http.py", line 40, in inner
    return func(request, *args, **kwargs)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django_unicorn/views/__init__.py", line 460, in message
    json_result = _handle_component_request(request, component_request)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django_unicorn/views/__init__.py", line 310, in _handle_component_request
    return _process_component_request(request, component_request)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django_unicorn/views/__init__.py", line 118, in _process_component_request
    ) = call_method.handle(component_request, component, action.payload)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django_unicorn/views/action_parsers/call_method.py", line 86, in handle
    return_data.value = _call_method_name(component, method_name, args, kwargs)
  File "<decorator-gen-24>", line 2, in _call_method_name
    <source code not available>
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django_unicorn/decorators.py", line 66, in timed
    result = func(*args, **kwargs)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django_unicorn/views/action_parsers/call_method.py", line 132, in _call_method_name
    model = DbModel.objects.get(**{key: value})
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/db/models/manager.py", line 85, in manager_method
    return getattr(self.get_queryset(), name)(*args, **kwargs)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/db/models/query.py", line 424, in get
    clone = self._chain() if self.query.combinator else self.filter(*args, **kwargs)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/db/models/query.py", line 941, in filter
    return self._filter_or_exclude(False, args, kwargs)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/db/models/query.py", line 961, in _filter_or_exclude
    clone._filter_or_exclude_inplace(negate, args, kwargs)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/db/models/query.py", line 968, in _filter_or_exclude_inplace
    self._query.add_q(Q(*args, **kwargs))
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/db/models/sql/query.py", line 1393, in add_q
    clause, _ = self._add_q(q_object, self.used_aliases)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/db/models/sql/query.py", line 1412, in _add_q
    child_clause, needed_inner = self.build_filter(
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/db/models/sql/query.py", line 1347, in build_filter
    condition = self.build_lookup(lookups, col, value)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/db/models/sql/query.py", line 1193, in build_lookup
    lookup = lookup_class(lhs, rhs)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/db/models/lookups.py", line 25, in __init__
    self.rhs = self.get_prep_lookup()
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/db/models/lookups.py", line 77, in get_prep_lookup
    return self.lhs.output_field.get_prep_value(self.rhs)
  File "/Users/triopter/.local/share/virtualenvs/poc_uni-QNOZ3vZ_/lib/python3.8/site-packages/django/db/models/fields/__init__.py", line 1825, in get_prep_value
    raise e.__class__(

Exception Type: TypeError at /unicorn/message/table-row
Exception Value: Field 'id' expected a number but got <TableCell: Certain usually speak pressure gun image manager. Whose prevent state indicate society beautiful decide. Clearly financial shake seem director.>.```

Debugging, I determined that the only cases in which the error was occurring were the ones in which the body of `django_unicorn.call_method_parser.parse_call_method_name` was not entered.  Commenting out the `lru_cache` decorator has resolved the problem, and it now succeeds consistently.  I suspect this has something to do with hydration changing a cached value somewhere.

[adamghill]

Hmm, interesting. I don't think I've ever seen this happen while I've been testing. Any chance you could fork this repo and reproduce this in the example project? That way I could see more easily what is going on, thanks!

[adamghill]

If I specify typed=True (as referenced in https://docs.python.org/3/library/functools.html#functools.lru_cache) it would prevent the exception (although, not sure if there is a separate issue that is happening). I'm going to try that and you can let me know if it clears up.

[adamghill]

Done in 6d72278. Closing, but feel free to open this again if you see it continue to happen in 0.34.0.