[Python] How to create instance of a Pydantic model with subset fields

This is the model

class UsersInformationModel(BaseDataModel):
id: Optional[int] = None
is_vip: bool = False
creation_tag: Optional[dict] = None # JSON field mapped to a dictionary
user_id: int # Not nullable
created_at: Optional[datetime] = None
updated_at: Optional[datetime] = None
branch_id: Optional[int] = None
setting: Optional[dict] = None # JSON field mapped to a dictionary
vip_type: int = 0
medication_history: Optional[bool] = None
other_disease: Optional[str] = None
tobacco_alcohol_use: Optional[bool] = None
consumed_medications: Optional[str] = None
consumed_medications_amount: Optional[str] = None


and BaseDataModel

from pydantic import BaseModel, PrivateAttr, root_validator
from typing import Dict, Any


class BaseDataModel(BaseModel):
_explicit_fields: set = PrivateAttr(default_factory=set)

class Config:
# Pydantic settings
populate_by_name = True
exclude_unset = True

@root_validator(pre=True)
def validate_fields(cls, values):
# This ensures that only explicitly set fields are retained in the model
for field in values.copy():
if field not in cls.__fields__:
del values[field]
return values

def dict(self, **kwargs):
# Ensure fields are excluded if not set (only non-None fields are included)
return super().model_dump(exclude_unset=True, **kwargs)


The problem is when I write:

data = {
'user_id': self.current_user.id,
'medication_history': self.data.medication_history,
'other_disease': self.data.other_disease,
'tobacco_alcohol_use': self.data.tobacco_alcohol_use,
'consumed_medications': self.data.consumed_medications,
'branch_id': None,
'consumed_medications_amount': self.data.consumed_medications_amount,
}
data = UsersInformationModel(**data)
data_dict = data.dict()


The data contains all of the model's fields and sets the non-mentioned fields to None, but the data_dict is OK and only contains fields included in the data.

How can I change BaseDataModel so that data only contains the mentioned fields? No matter if the value is None, I want it to have only explicitly included fields.

Continue reading...