Timer Trigger arg_name cannot use snake case

[williamhbell]

Investigative information

func --version
4.0.5530

Repro steps

Provide the steps required to reproduce the problem:

• Create a new Azure function

func new --template "Timer Trigger" --name another_trigger

• Change the generated code from

@app.timer_trigger(schedule="0 */5 * * * *", arg_name="myTimer", run_on_startup=True,
              use_monitor=False) 
def another_trigger(myTimer: func.TimerRequest) -> None:

to

@app.timer_trigger(schedule="0 */5 * * * *", arg_name="my_timer", run_on_startup=True,
              use_monitor=False) 
def another_trigger(my_timer: func.TimerRequest) -> None:

• Run the function, which results in an error of the form:

The 'another_trigger' function is in error: The binding name my_timer is invalid. Please assign a valid name to the binding.

Expected behaviour

It should be possible to use a binding name that uses snake case, since this is the normal convention for Python programs.

Actual behaviour

The 'another_trigger' function is in error: The binding name my_timer is invalid. Please assign a valid name to the binding.

Known workarounds

Remove the _ character from the binding and variable name.

Contents of the requirements.txt file:

azure-functions==1.18.0

[bhagyshricompany]

Thanks for reporting will check and update.Thanks

[bhagyshricompany]

Hi @williamhbell pls have a look this is not supported.Azure/azure-functions-python-worker#1174

[williamhbell]

@bhagyshricompany thanks for spotting Azure/azure-functions-python-worker#1174. It appears to be the same bug. As mentioned in Azure/azure-functions-python-worker#1174, snake case is normally used for Python variables following PEP8 https://peps.python.org/pep-0008/#function-and-variable-names .

[bhagyshricompany]

yes but right now not have support.

[YunchuWang]

the validation is done in azure functions host at

azure-functions-host/src/WebJobs.Script/Utility.cs

Line 60 in 1ed9465

private static readonly Regex BindingNameValidationRegex = new Regex(string.Format("^([a-zA-Z][a-zA-Z0-9]{{0,127}}|{0})$", Regex.Escape(ScriptConstants.SystemReturnParameterBindingName)));

.

[YunchuWang]

Transferring to Azure Function Host to continue the discussion