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Literals should raise a more friendly error message #2160
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Nice, yeah looks like we can do something like
from typing import Any, Literal from pydantic import BaseModel, Field, field_validator class MyModel(BaseModel): my_literal: Literal[1] = Field(alias="my-literal") @field_validator("my_literal", mode="before") def validate_my_literal(cls, v: Any) -> int: """Validate that my_literal is 1 for MyModel.""" if v != 1: raise ValueError(f"MyModel requires my-literal to be 1, got {v}") return v MyModel(**{"my-literal": 2})
Which raises
pydantic_core._pydantic_core.ValidationError: 1 validation error for MyModel my-literal Value error, MyModel requires my-literal to be 1, got 2 [type=value_error, input_value=2, input_type=int] For further information visit https://errors.pydantic.dev/2.11/v/value_errorThis issue has been automatically marked as stale because it has been open for 180 days with no activity. It will be closed in next 14 days if no further activity occurs. To permanently prevent this issue from being considered stale, add the label 'not-stale', but commenting on the issue is preferred when possible.
This issue has been closed because it has not received any activity in the last 14 days since being marked as 'stale'
We should find a way to make sure that incorrect Literals raise a friendlier error message than the standard Pydantic error message. Pydantic might be able to do this for us.
Context: #2154 (comment)