Is it possible to configure export arguments?

[Midnighter]

Question

Output of python -c "import pydantic.utils; print(pydantic.utils.version_info())":

             pydantic version: 1.4
            pydantic compiled: True
                 install path: ~/.virtualenvs/structurizr/lib/python3.6/site-packages/pydantic
               python version: 3.6.9 (default, Nov  7 2019, 10:44:02)  [GCC 8.3.0]
                     platform: Linux-5.3.0-7642-generic-x86_64-with-Ubuntu-18.04-bionic
     optional deps. installed: []

I have an application where my models should always be exported with by_alias=True and exclude_unset=True. Similarly to what is proposed in #660, I was looking to add these to the models' Config but that's not possible at the moment.

What is the right way to achieve this? Should I override the dict and json methods as below?

from typing import Set

from pydantic import BaseModel, Field


class ModelTest(BaseModel):

    id: str = Field("")
    origin_id: str = Field("", alias="originId")
    tags: Set[str] = Field(())

    def dict(self, **kwargs):
        kwargs.setdefault("by_alias", True)
        kwargs.setdefault("exclude_unset", True)
        return super().dict(**kwargs)

    def json(self, **kwargs):
        kwargs.setdefault("by_alias", True)
        kwargs.setdefault("exclude_unset", True)
        return super().json(**kwargs)

[PrettyWood]

Hi @Midnighter ! As it is indeed unavailable in the Config, I would personally go with a custom BaseModel that I would use in my whole application.

class MyBaseModel(BaseModel):
    def dict(self, by_alias=True, exclude_unset=True, **kwargs):
        return super().dict(by_alias=by_alias, exclude_unset=exclude_unset, **kwargs)

    def json(self, by_alias=True, exclude_unset=True, **kwargs):
        return super().json(by_alias=by_alias, exclude_unset=exclude_unset, **kwargs)

class ModelTest(MyBaseModel):
    id: str = Field("")
    origin_id: str = Field("", alias="originId")
    tags: Set[str] = Field(())

m = ModelTest(originId='myid')
print(m.dict())
# > {'originId': 'myid'}
print(m.dict(exclude_unset=False))
# > {'id': '', 'originId': 'myid', 'tags': ()}
print(m.json())
# > {"originId": "myid"}

This way it allows you to easily change the default values and maybe one day use a more "native" way.

[Midnighter]

Okay, thank you 😃

[mdavis-xyz]

Why was this issue closed?

@PrettyWood 's response sounds like a great workaround. But can I still write a PR to change pydantic so future users don't need the workaround?

i.e. so that this MWE works:

from pydantic import BaseModel
from typing import Optional

class MyModel(BaseModel):
    x: Optional[int]
    class Config:
        exclude_none = True

assert MyModel().dict(exclude_none=False)['x'] == None
assert 'x' not in MyModel().dict()