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Description
- cattrs version: 24.1.2
- Python version: 3.11
- Operating System: Linux/MacOSX
Description
I am not sure how to handle union with subclass.
What I Did
import attr
import cattr
from cattrs.strategies import configure_tagged_union, include_subclasses
@attr.s(frozen=True, auto_attribs=True)
class A:
pass
@attr.s(frozen=True, auto_attribs=True)
class B:
pass
@attr.s(frozen=True, auto_attribs=True)
class B2(B):
b: int
@attr.s(frozen=True, auto_attribs=True)
class C:
x: A | B
CONVERTER = cattr.Converter()
configure_tagged_union(A | B, CONVERTER)
union_strategy = partial(configure_tagged_union, tag_name="type_name")
include_subclasses(B, CONVERTER, union_strategy=union_strategy)
if __name__ == "__main__":
instance = C(x=B2(b=1))
r = CONVERTER.unstructure(instance, unstructure_as=C)
print(r)
print(CONVERTER.structure(r, C))
Getting error as
Traceback (most recent call last):
File "..../IPython/core/interactiveshell.py", line 3577, in run_code
exec(code_obj, self.user_global_ns, self.user_ns)
File "<ipython-input-1-8e14e71c7dee>", line 1, in <module>
CONVERTER.unstructure(instance, unstructure_as=C)
File ".../python3.11/site-packages/cattrs/converters.py", line 300, in unstructure
return self._unstructure_func.dispatch(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "<cattrs generated unstructure __main__.C>", line 3, in unstructure_C
'x': __c_unstr_x(instance.x),
^^^^^^^^^^^^^^^^^^^^^^^
File ".../python3.11/site-packages/cattrs/strategies/_unions.py", line 82, in unstructure_tagged_union
res = _exact_cl_unstruct_hooks[val.__class__](val)
~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
KeyError: <class '__main__.B2'>
^CTraceback (most recent call last):
File ".../example.py", line 99, in <module>
r = CONVERTER.unstruct
My understanding is that configure_tagged_union
does not register all the hooks for subclasses. I wonder what is the right/best way to workaround it?
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