The Message.FromString() Python method is missing from online documentation

[dlenskiSB]

Version: main

Operating System: Linux, but irrelevant

Runtime: Python 3.12

The undocumented method in question

With the python-protobuf package installed locally, pydoc shows the existence of a class/static method FromString() which creates a new instance from serialized data ("method" in the docstring doesn't make much sense, but 🤷🏻‍♂️):

$ pydoc3 google._upb._message.Message|grep -C3 FromString
 |  Class methods defined here:
 |
 |  FromString(...)
 |      Creates new method instance from given serialized data.

The C source of this method is found at:

protobuf/python/message.c

Lines 1525 to 1542 in 9668016

	static PyObject* PyUpb_Message_FromString(PyObject* cls, PyObject* serialized) {
	PyObject* ret = NULL;
	PyObject* length = NULL;
	ret = PyObject_CallObject(cls, NULL);
	if (ret == NULL) goto err;
	length = PyUpb_Message_MergeFromString(ret, serialized);
	if (length == NULL) goto err;
	done:
	Py_XDECREF(length);
	return ret;
	err:
	Py_XDECREF(ret);
	ret = NULL;
	goto done;
	}

What does the documentation currently show?

The .ParseFromString and .MergeFromString methods are well-documented and widely seen in real-world Python protobuf code.

The .FromString static/class method is BASICALLY UNDOCUMENTED:

• not mentioned in https://protobuf.dev/getting-started/pythontutorial/#parsing-serialization
• empty docs in https://googleapis.dev/python/protobuf/latest/google/protobuf/message.html#google.protobuf.message.Message.FromString

What should the documentation show?

I expect to see the .FromString method in online documentation.

It allows more concise and Pythonic deserialization of Protobuf messages, because it combines instantiating the Message sub-class with calling .ParseFromString() on it:

from foo_pb2 import FooMessage

serialized_bytes = b'...'   # serialized message

# Documented two-step approach
msg1 = FooMessage()
msg1.ParseFromString(serialized_bytes)

# UNDOCUMENTED one-step approach
msg2 = FooMessage.FromString(serialized_bytes)

assert msg1 == msg2