Question: Is it possible to raise an error when data for a non-registered target is parsed? about streaming-form-data

[hbusul]

@siddhantgoel thanks for reviewing and merging the changes! Now that it is merged, I'm closing the issue.

[siddhantgoel]

At the moment the parser passes everything unknown to a NullTarget() so it should definitely be possible to raise an error instead. I have the feeling though that raising an error has the potential to break existing code.

There could be the case where a form contains 5 fields and on the backend we only care about the performance for 4 fields and the fifth field is outside the scope of this library. Maybe a warnings.warn() call would be a lightweight alternative of achieving a similar thing?

[hbusul]

I agree that it should not be the default behavior. For example in the flask-restx library there is a flag for the parser called strict and by default it is false. When you set it to true, it raises an exception when an unknown field is provided. Doing it that way would be backwards compatible as well. However I do not have any strong preference, as long as I can catch the error one way or another.

[siddhantgoel]

I do like the idea of a strict mode. Would you be up for opening a PR? I think there are very few function signatures we'd need to adjust, and then update the documentation.

[hbusul]

Sure, then I'll try to implement it. I always wanted to test Cython as long as you review why not :D

[siddhantgoel]

Awesome! 🎉

Just something to get you started with: the streaming_form_data.parser.Parser class is the Python entry-point while the _Parser class is the one running in Cython space. There's a streaming_form_data._parser._Parser._part_for method that is called to get the current Part (basically the current chunk of input being uploaded) while the parsing is being done to feed it some bytes. Inside the parsing loop there's a part = self._part_for(name) or self.default_part check so that's probably where you would need to return an error.

Let me know if there's anything I can help with and looking forward to seeing that PR!

[hbusul]

Thanks a lot, I will look into those!