Progress not functional because kind is missing

[perrinjerome]

The classes used for progress API all have a kind property which is used in the LSP protocol so that the client knows if it's a begin, progress or end message:

pygls/pygls/lsp/types/basic_structures.py

Lines 442 to 459 in 4772250

	class WorkDoneProgressBegin(Model):
	kind: str = 'begin'
	title: str
	cancellable: Optional[bool]
	message: Optional[str]
	percentage: Optional[NumType]
	class WorkDoneProgressReport(Model):
	kind: str = 'report'
	cancellable: Optional[bool]
	message: Optional[str]
	percentage: Optional[NumType]
	class WorkDoneProgressEnd(Model):
	kind: str = 'end'
	message: Optional[str]

When these classes are used, usually the kind attribute is not set in the constructor, as we can see in the json example, it is:

pygls/examples/json-extension/server/server.py

Line 205 in 4772250

ls.progress.begin(token, WorkDoneProgressBegin(title='Indexing', percentage=0))

and the kind is not passed explicitly like that:

    ls.progress.begin(token, WorkDoneProgressBegin(title='Indexing', percentage=0,         kind='begin'))

Because it is default value of the model, it's not needed to specify the kind and this is more elegant to not pass the kind.

The whole progress example stopped working after b84098c , more specifically this chunk which removes this code:

pygls/pygls/lsp/types/basic_structures.py

Lines 57 to 63 in ee17487

	def __init__(self, **data: Any) -> None:
	super().__init__(**data)
	# Serialize (.json()) fields that has default value which is not None
	for name, field in self.__fields__.items():
	if getattr(field, 'default', None) is not None:
	self.__fields_set__.add(name)

This block was responsible for serialising the kind attributes that are set as default values.

As we can see in log file, this message is serialised without kind.

INFO:pygls.protocol:Sending data: {"jsonrpc": "2.0", "method": "$/progress", "params": {"token": "6f82fd14-87e4-403c-9c33-0cdc92c54cbd", "value": {"title": "Indexing", "percentage": 0}}}

If we add back the __init__ method, then kind is properly serialised and the progress example works.

PS: very few of the protocol classes are using default values like this, maybe there is only the ones used for progress and also CreateFile DeleteFile and DeleteFile.

PPS: an easy workaround is to specify the kind explicitly

[dimbleby]

#198 (comment)

[perrinjerome]

Thanks @dimbleby the suggestion from #198 (comment) would also solve the issue.

[tombh]

Fixed in #236