Pipe | as alternative of Union is not working properly

[visko-sc]

from dataclasses import dataclass

from dataclasses_jsonschema import JsonSchemaMixin


@dataclass
class Numbers(JsonSchemaMixin):
    roman: str


@dataclass
class Math(JsonSchemaMixin):
    numbers: Numbers | None = None


print(Math(Numbers('X')).to_dict())

Actual result:
{'numbers': Numbers(roman='X')}

Expected result:
{'numbers': {'roman': 'X'}}

I think the problem can be fixed in either _get_field_type_name or in

dataclasses-jsonschema/dataclasses_jsonschema/__init__.py

Line 391 in 648ada2

elif field_type_name == "Union":

Note:
These work as expected:

@dataclass
class Math2(JsonSchemaMixin):
    numbers: Union[Numbers, None] = None


@dataclass
class Math3(JsonSchemaMixin):
    numbers: Optional[Numbers] = None

[ZdenekM]

Duplicate of #187?

[visko-sc]

They are related. But while #187 brings a specific problem (str | None) and schema creation, this is about the pipe operator and data class creation error. The root cause is probably the same.

[s-knibbs]

Adding from __future__ import annotations at the top fixed the example code you posted.