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
Description
Initial Checks
- I confirm that I'm using Pydantic V2
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:
File "C:\Users\tom.mclean\AppData\Roaming\JetBrains\PyCharmCE2023.3\scratches\scratch_6.py", line 102, in <module>
BooCondition = create_conditions_type(Foo)
^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Roaming\JetBrains\PyCharmCE2023.3\scratches\scratch_6.py", line 87, in create_conditions_type
AndCondition[return_value_type],
~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\main.py", line 687, in __class_getitem__
submodel = _generics.create_generic_submodel(model_name, origin, args, params)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_generics.py", line 138, in create_generic_submodel
created_model = meta(
^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_model_construction.py", line 178, in __new__
set_model_fields(cls, bases, config_wrapper, types_namespace)
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_model_construction.py", line 452, in set_model_fields
fields, class_vars = collect_model_fields(cls, bases, config_wrapper, types_namespace, typevars_map=typevars_map)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_fields.py", line 232, in collect_model_fields
field.apply_typevars_map(typevars_map, types_namespace)
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\fields.py", line 556, in apply_typevars_map
self.annotation = _generics.replace_types(annotation, typevars_map)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_generics.py", line 290, in replace_types
resolved_type_args = tuple(replace_types(arg, type_map) for arg in type_args)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_generics.py", line 290, in <genexpr>
resolved_type_args = tuple(replace_types(arg, type_map) for arg in type_args)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_generics.py", line 282, in replace_types
annotated = replace_types(annotated_type, type_map)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_generics.py", line 290, in replace_types
resolved_type_args = tuple(replace_types(arg, type_map) for arg in type_args)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_generics.py", line 290, in <genexpr>
resolved_type_args = tuple(replace_types(arg, type_map) for arg in type_args)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_generics.py", line 323, in replace_types
return type_[resolved_type_args]
~~~~~^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\main.py", line 687, in __class_getitem__
submodel = _generics.create_generic_submodel(model_name, origin, args, params)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_generics.py", line 138, in create_generic_submodel
created_model = meta(
^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_model_construction.py", line 183, in __new__
complete_model_class(
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_model_construction.py", line 527, in complete_model_class
schema = gen_schema.clean_schema(schema)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_generate_schema.py", line 427, in clean_schema
schema = _discriminated_union.apply_discriminators(schema)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_discriminated_union.py", line 56, in apply_discriminators
return simplify_schema_references(_core_utils.walk_core_schema(schema, inner))
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 416, in walk_core_schema
return f(schema.copy(), _dispatch)
^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_discriminated_union.py", line 44, in inner
s = recurse(s, inner)
^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 199, in walk
return f(schema, self._walk)
^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_discriminated_union.py", line 44, in inner
s = recurse(s, inner)
^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 202, in _walk
schema = self._schema_type_to_method[schema['type']](schema.copy(), f)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 234, in handle_definitions_schema
updated_definition = self.walk(definition, f)
^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 199, in walk
return f(schema, self._walk)
^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_discriminated_union.py", line 44, in inner
s = recurse(s, inner)
^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 202, in _walk
schema = self._schema_type_to_method[schema['type']](schema.copy(), f)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 211, in _handle_other_schemas
schema['schema'] = self.walk(sub_schema, f) # type: ignore
^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 199, in walk
return f(schema, self._walk)
^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_discriminated_union.py", line 44, in inner
s = recurse(s, inner)
^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 202, in _walk
schema = self._schema_type_to_method[schema['type']](schema.copy(), f)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 339, in handle_model_fields_schema
replaced_field['schema'] = self.walk(v['schema'], f)
^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 199, in walk
return f(schema, self._walk)
^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_discriminated_union.py", line 44, in inner
s = recurse(s, inner)
^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 202, in _walk
schema = self._schema_type_to_method[schema['type']](schema.copy(), f)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 254, in handle_list_schema
schema['items_schema'] = self.walk(items_schema, f)
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_core_utils.py", line 199, in walk
return f(schema, self._walk)
^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_discriminated_union.py", line 53, in inner
s = apply_discriminator(s, discriminator, definitions)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_discriminated_union.py", line 95, in apply_discriminator
return _ApplyInferredDiscriminator(discriminator, definitions or {}).apply(schema)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_discriminated_union.py", line 190, in apply
schema = self._apply_to_root(schema)
^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_discriminated_union.py", line 230, in _apply_to_root
self._handle_choice(choice)
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_discriminated_union.py", line 305, in _handle_choice
inferred_discriminator_values = self._infer_discriminator_values_for_choice(choice, source_name=None)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_discriminated_union.py", line 384, in _infer_discriminator_values_for_choice
return self._infer_discriminator_values_for_choice(self.definitions[schema_ref], source_name=source_name)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\tom.mclean\AppData\Local\miniconda3\envs\Module\Lib\site-packages\pydantic\_internal\_discriminated_union.py", line 386, in _infer_discriminator_values_for_choice
raise TypeError(
TypeError: 'none' is not a valid discriminated union variant; should be a `BaseModel` or `dataclass`
Example Code
from __future__ import annotations
from pydantic import BaseModel, Field
from typing import Annotated, Union, Literal, Generic, TypeVar, Optional
from abc import ABC, abstractmethod
ReturnValueType = TypeVar("ReturnValueType")
class BaseCondition(BaseModel, ABC, Generic[ReturnValueType]):
type: str
value: Optional[ReturnValueType] = None
@abstractmethod
def passes(self, values: dict[str, float]) -> bool:
pass
class IsInIntervalCondition(BaseCondition[ReturnValueType]):
type: Literal["interval"] = "interval"
key: str
gt: Optional[float] = None
lt: Optional[float] = None
gte: Optional[float] = None
lte: Optional[float] = None
def passes(self, value: dict[str, float]) -> bool:
value = value[self.key]
if self.gt is not None and value <= self.gt:
return False
if self.lt is not None and value >= self.lt:
return False
if self.gte is not None and value < self.gte:
return False
if self.lte is not None and value > self.lte:
return False
return True
class InSetCondition(BaseCondition[ReturnValueType]):
type: Literal["set"] = "set"
values: list[float]
key: str
def passes(self, values: dict[str, float]) -> bool:
if self.key not in values:
return False
return values[self.key] in values
class AndCondition(BaseCondition[ReturnValueType]):
type: Literal["and"] = "and"
conditions: list[Conditions]
def passes(self, values: dict[str, float]):
for condition in self.conditions:
if not condition.passes(values):
return False
return True
class OrCondition(BaseCondition[ReturnValueType]):
type: Literal["or"] = "or"
conditions: list[Conditions]
def passes(self, value: dict[str, float]) -> bool:
for i in self.conditions:
if i.passes(value):
return True
return False
class AlwaysCondition(BaseCondition[ReturnValueType]):
type: Literal["always"] = "always"
def passes(self, value: dict[str, float]) -> bool:
return True
def create_conditions_type(return_value_type) -> type:
return Annotated[
Union[
IsInIntervalCondition[return_value_type],
InSetCondition[return_value_type],
AndCondition[return_value_type],
OrCondition[return_value_type],
AlwaysCondition[return_value_type]
],
Field(discriminator="type")
]
Conditions = create_conditions_type(ReturnValueType)
class Foo(BaseModel):
x: str
FooCondition = create_conditions_type(Foo)
class Bar(BaseModel):
foo_condition: FooConditionPython, Pydantic & OS Version
pydantic version: 2.6.4
pydantic-core version: 2.16.3
pydantic-core build: profile=release pgo=true
install path: C:\Users\tom.mclean\AppData\Local\miniconda3\envs\PitchLights\Lib\site-packages\pydantic
python version: 3.11.7 | packaged by Anaconda, Inc. | (main, Dec 15 2023, 18:05:47) [MSC v.1916 64 bit (AMD64)]
platform: Windows-10-10.0.19045-SP0
related packages: typing_extensions-4.9.0
commit: unknown