I am trying to parse MongoDB data to a pydantic schema but fail to read its _id
field which seem to just disappear from the schema.
The issue is definitely related to the underscore in front of the object attribute. I can’t change _id
field name since that would imply not parsing the field at all.
Please find below the code I use (using int
instead of ObjectId
for the sake of simplification)
from pydantic import BaseModel class User_1(BaseModel): _id: int data_1 = {"_id": 1} parsed_1 = User_1(**data_1) print(parsed_1.schema()) class User_2(BaseModel): id: int data_2 = {"id": 1} parsed_2 = User_2(**data_2) print(parsed_2.schema())
User_1
is parsed successfully since its _id
field is required but can’t be read afterwards.
User_2
works in the above example by fails if attached to Mongo which doesn’t provide any id
field but _id
.
Output of the code above reads as follows:
User_1 {'title': 'User_1', 'type': 'object', 'properties': {}} User_2 {'title': 'User_2', 'type': 'object', 'properties': {'id': {'title': 'Id', 'type': 'integer'}}, 'required': ['id']}
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Answer
you need to use an alias for that field name
from pydantic import BaseModel, Field class User_1(BaseModel): id: int = Field(..., alias='_id')
See the docs here.