Validating a dict value agains a Literal type gives the wrong ValidationError #6188
Description
Initial Checks
- I have searched GitHub for a duplicate issue and I'm sure this is something new
- I have searched Google & StackOverflow for a solution and couldn't find anything
- I have read and followed the docs and still think this is a bug
- I am confident that the issue is with pydantic (not my code, or another library in the ecosystem like FastAPI or mypy)
Description
Validating a dict value agains a Literal type gives the wrong ValidationError. Instead of unexpected value; permitted: '*' the validation error just says unhashable type: 'dict' (type=type_error). Which does not describe the problem and is confusing, e.g. if handing this to API users in fastAPI. I would also expect an unexpected value; permitted: '*' for all non string values.
The respective validator in pydantic/validators.py (line 480ff) only catches a KeyError:
def make_literal_validator(type_: Any) -> Callable[[Any], Any]:
permitted_choices = all_literal_values(type_)
# To have a O(1) complexity and still return one of the values set inside the `Literal`,
# we create a dict with the set values (a set causes some problems with the way intersection works).
# In some cases the set value and checked value can indeed be different (see `test_literal_validator_str_enum`)
allowed_choices = {v: v for v in permitted_choices}
def literal_validator(v: Any) -> Any:
try:
return allowed_choices[v]
except KeyError:
raise errors.WrongConstantError(given=v, permitted=permitted_choices)
return literal_validatorIMHO, it should also catch a TypeError (i.e. the "unhashable type") and produce a corresponding error. Or, it could check for isinstance(v, str) first and raise respective error if it is not a string.
Example Code
import pydantic
from typing import Literal
pydantic.parse_obj_as(Literal['*'], {})Python, Pydantic & OS Version
pydantic version: 1.10.9
pydantic compiled: True
install path: ********.pyenv/lib/python3.9/site-packages/pydantic
python version: 3.9.16 (main, Dec 7 2022, 10:16:11) [Clang 14.0.0 (clang-1400.0.29.202)]
platform: macOS-13.2-x86_64-i386-64bit
optional deps. installed: ['devtools', 'dotenv', 'email-validator', 'typing-extensions']
Affected Components
- Compatibility between releases
- Data validation/parsing
- Data serialization -
.dict()and.json() - JSON Schema
- Dataclasses
- Model Config
- Field Types - adding or changing a particular data type
- Function validation decorator
- Generic Models
- Other Model behaviour -
construct(), pickling, private attributes, ORM mode - Plugins and integration with other tools - mypy, FastAPI, python-devtools, Hypothesis, VS Code, PyCharm, etc.