Discriminated union type breaks from 2.6.3 to 2.6.4: TypeError: 'none' is not a valid discriminated union variant; should be a BaseModel or dataclass
#9118
Comments
mcleantom
added
bug V2
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Thanks a ton for reporting this. We'll look into a fix for 2.7! |
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So I'll note that without the generic complexity, this simplified version works: from __future__ import annotations
from typing import Annotated, Literal, List, Union
from pydantic import BaseModel, Field
class Dog(BaseModel):
type_: Literal['dog']
friends: List[Pet]
class Cat(BaseModel):
type_: Literal['cat']
friends: List[Pet]
Pet = Annotated[Union[Dog, Cat], Field(..., discriminator='type_')]I'm working on creating an MRE with the generic complexity. |
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Ah here we go: from __future__ import annotations
from typing import Annotated, Literal, List, Union, TypeVar, Generic
from pydantic import BaseModel, Field, TypeAdapter
T = TypeVar('T')
class Dog(BaseModel, Generic[T]):
type_: Literal['dog']
friends: List[GenericPet]
id: T
class Cat(BaseModel, Generic[T]):
type_: Literal['cat']
friends: List[GenericPet]
id: T
GenericPet = Annotated[Union[Dog[T], Cat[T]], Field(..., discriminator='type_')]
ta = TypeAdapter(Dog[int])
#> TypeError: 'none' is not a valid discriminated union variant; should be a `BaseModel` or `dataclass` |
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I've opened a PR with a fix - this will be released in 2.7 soon (beginning of next week) |
Amazing! Thanks! |
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Description
I have some pydantic models that I am using to make configurable models based on conditions, they are quite complicated being self-referencing and generic. My code works in 2.6.3 but breaks in 2.6.4.
In 2.6.4 I get the error:
Example Code
Python, Pydantic & OS Version
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