faust-streaming/faust

Union of types is not supported

xcarlosamm opened this issue · 4 comments

xcarlosamm commented

Checklist

  • I have included information about relevant versions
  • I have verified that the issue persists when using the master branch of Faust.

Steps to reproduce

The following model raises a NotImplementedError exception

from typing import Union, List
import faust

class Person(faust.Record):
    emails: Union[str, List[str]]

Expected behavior

Declare fields with the union of types without exception

Actual behavior

An exception is raised

Full traceback

Traceback (most recent call last):
  File "/venv/poc/lib/python3.8/site-packages/venusian/__init__.py", line 220, in scan
    __import__(modname)
  File "/mnt/c/projects/dedalowcoding-streams/myapp/models.py", line 14, in <module>
    class Person(faust.Record):
  File "/venv/poc/lib/python3.8/site-packages/faust/models/record.py", line 114, in __init_subclass__
    super().__init_subclass__(
  File "/venv/poc/lib/python3.8/site-packages/faust/models/base.py", line 296, in __init_subclass__
    finalizer()
  File "/venv/poc/lib/python3.8/site-packages/faust/models/base.py", line 374, in _init_subclass
    options.descriptors = cls._contribute_field_descriptors(cls, options)
  File "/venv/poc/lib/python3.8/site-packages/faust/models/record.py", line 285, in _contribute_field_descriptors
    descr.on_model_attached()
  File "/venv/poc/lib/python3.8/site-packages/faust/models/fields.py", line 172, in on_model_attached
    self._to_python = self._compile_type_expression()
  File "/venv/poc/lib/python3.8/site-packages/faust/models/fields.py", line 185, in _compile_type_expression
    comprehension = expr.as_function(stacklevel=2)
  File "/venv/poc/lib/python3.8/site-packages/faust/models/typing.py", line 676, in as_function
    sourcecode = self.as_string(name=name, argument_name=argument_name)
  File "/venv/poc/lib/python3.8/site-packages/faust/models/typing.py", line 693, in as_string
    expression = self.as_comprehension(argument_name)
  File "/venv/poc/lib/python3.8/site-packages/faust/models/typing.py", line 702, in as_comprehension
    return self.build(Variable(argument_name), self.expr)
  File "/venv/poc/lib/python3.8/site-packages/faust/models/typing.py", line 705, in build
    return self._build_expression(var, *args)
  File "/venv/poc/lib/python3.8/site-packages/faust/models/typing.py", line 710, in _build_expression
    res = node.build(var, *type_info.args)
  File "/venv/poc/lib/python3.8/site-packages/faust/models/typing.py", line 334, in build
    raise NotImplementedError(f"Union of types {args!r} not supported")
NotImplementedError: Union of types (<class 'str'>, typing.List[str]) not supported

Versions

  • Python version: 3.8.10
  • Faust version: 0.10.0
  • Operating system: Ubuntu 20.04
  • Kafka version: 7.3.0 (Confluent docker)
wbarnha commented

This is a known issue, unfortunately. For now you'll need to use:

class Person(faust.Record):
    emails: list

I'll review the current state of typing in Records and see if I can make something work.

  • 👍1