Some of the Pydantic models in my FastAPI project include secret internal fields that I don’t want to expose in the API response or generated documentation. For example, I would like to exclude the fields address
and created_at
in the User
model below:
from pydantic import BaseModel from datetime import datetime class User(BaseModel): username: str email: str address: str created_at: datetime
How do I keep these fields from appearing in responses while keeping them in the model?
To exclude multiple fields from a Pydantic model, we can expand the type definition using Annotated
from Python’s built-in typing
module. This special typing form was proposed in PEP 593 and is used to add specific metadata to type declarations. This metadata is being used by libraries such as Pydantic to enable special behavior. In this case, we’ll use it to exclude the address
and created_at
fields from our API’s responses:
from pydantic import BaseModel, Field # also import Field from datetime import datetime from typing import Annotated # import Annotated class User(BaseModel): username: str email: str address: Annotated[str, Field(exclude=True)] created_at: Annotated[datetime, Field(exclude=True)]
Note that all of Pydantic’s standard validation features will still work for excluded fields.
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