Usage with mypy
pydantic models work with mypy provided you use the annotation-only version of required fields:
from datetime import datetime from typing import List, Optional from pydantic import BaseModel, NoneStr class Model(BaseModel): age: int first_name = 'John' last_name: NoneStr = None signup_ts: Optional[datetime] = None list_of_ints: List[int] m = Model(age=42, list_of_ints=[1, '2', b'3']) print(m.middle_name) # not a model field! Model() # will raise a validation error for age and list_of_ints
You can run your code through mypy with:
mypy \ --ignore-missing-imports \ --follow-imports=skip \ --strict-optional \ pydantic_mypy_test.py
If you call mypy on the example code above, you should see mypy detect the attribute access error:
13: error: "Model" has no attribute "middle_name"
For your code to pass with
--strict-optional, you need to to use
Optional or an alias of
for all fields with
None as the default. (This is standard with mypy.)
Pydantic provides a few useful optional or union types:
If these aren't sufficient you can of course define your own.
Pydantic ships with a mypy plugin that adds a number of important pydantic-specific features to mypy that improve its ability to type-check your code.
See the pydantic mypy plugin docs for more details.