Provide option in RequestIdPlugin/CorrelationIdPlugin to always create a new UUID

Instead of accepting the user provided id, it would be nice if there was a way to always use the server-side generated id.

Currently, if the client has set the header to a value, that value is always preferred so the server doesn't generate a new one. It would be nice if both modes could be supported through a new kwarg which wouldn't introduce a breaking change.

starlette-context/starlette_context/plugins/correlation_id.py

Lines 14 to 22 in 79aa8ff

    
           async def extract_value_from_header_by_key( 
        
               self, request: Request 
        
           ) -> Optional[str]: 
        
               await super( 
        
                   CorrelationIdPlugin, self 
        
               ).extract_value_from_header_by_key(request) 
        
               if self.value is None: 
        
                   self.value = uuid.uuid4().hex 
        
               return self.value

Happy to submit a PR if needed.

Derek, let me start by saying I'm really happy to see new tickets. Keep it coming and let's discuss stuff!

I want to keep those plugins generic and simple. Also, I don't like passing booleans to methods that alter their behavior.

I was thinking about what you've suggested, whether it's your specific use case or people might need it and I think I could have used it myself. So let's do this!

I'm open to PRs but I don't think I have the time for reviewing and merging during weekdays.

Please feel free to open a PR. Otherwise, I will gladly implement this over the weekend.

	async def extract_value_from_header_by_key(
	self, request: Request
	) -> Optional[str]:
	await super(
	CorrelationIdPlugin, self
	).extract_value_from_header_by_key(request)
	if self.value is None:
	self.value = uuid.uuid4().hex
	return self.value