add exclude to Config

[samuelcolvin]

From a user perspective I would rather add an exclude in the Config metaclass instead of passing the dict in to .json(). One of my model's fields is a Callable and I would like to call .json() on it, however I need to instead pass a custom encoder to the .json() which still puts the responsibility on the caller.

Originally posted by @enkoder in #648 (comment)

[samuelcolvin]

as per #624 we could easily add exclude to a field, or even a dict to exclude sub-fields.

[JrooTJunior]

I guess to implements this like exporting roles in Schematics
That mechanism is good for writing API's

You can simply describe all of public fields in model and inside controllers make dump in required set of fields by specifying only the role name.

For example:

class User(BaseModel):
	id: int
	login: str
	email: str
	password: str
	first_name: str
	last_name: Optional[str] = None
	articles: Optional[List[Article]] = None

	register_date: datetime.datetime
	last_login: Optional[datetime.datetime] = None

	class Config:
		roles = {
			"self": {"exclude": {"password", "register_date", "last_login"}},
			"admin": {"exclude": {"password"}},
			"public": {"include": {"id", "email", "first_name", "last_name"}}
		}

And then:

user = User(
	id=42,
	login="mylogin",
	email="email@example.com",
	password="hashed secret password",
	first_name="Some",
	last_name="User",
	articles=[Article(id=1, label="foo"), Article(id=2, label="bar"), ...],
	register_date=datetime.datetime(...),
	last_login=datetime.datetime.now()
)
user.dump(role="public")

Should return something like this:

{
	"id": 42,
	"email": "email@example.com",
	"first_name": "Some",
	"last_name": "User",
}

include/exclude describing mechanism can be implemented more simply, for e.g. via function include(...)/exclude(...)

[enkoder]

Wow thanks for the quick response @samuelcolvin. I have just been exploring pydantic and I really like it. Having quick responses on PR's and active development certainly makes me even more excited to adopt it. Looking forward to working with you.

[dgasmith]

+1 for this, we code it into our classes as we have "local" variables that should not exported to other objects. Allowing this in the dict() on up would be optimal.

[Bobronium]

I like this idea and love @JrooTJunior's implementation with roles
I guess I'll be able to work on a new PR with these changes very soon, right after #648 will be merged

[samuelcolvin]

I understand that roles is neat, but I think it's a whole new concept that is unnecessarily complex for pydantic. If you did want roles it would be fairly trivial to add it to config and implement your own CustomBaseModel that used it as per #684.

I think exclude and include should use the fields property already in Config and also be configurable on Schema (soon to be Field, #577).

Combining this with #624, we'd have something like:

class User(BaseModel):
    id: int
    username: str
    password: str

class Transaction(BaseModel):
    id: str
    user: User
    value: int

    class Config:
        fields = {
            'value': {
                'alias': 'Amount',
                'exclude': ...,
            },
            'user': {
                'exclude': {'username', 'password'}
            },
            'id': {
                'dump_alias': 'external_id'
            }
        }

[xspirus]

Hello @samuelcolvin . First of all, I am really amazed by pydantic and, even though I haven't been using it for a long time, I think it can be really helpful in numerous situations.

On the point of this issue, as I understand, this has not been implemented yet, correct? Is there currently any work going on for this? If not, I am willing to have a go on this. Having include and exclude on Field and Config, in the way you described above, sounds like a really nice feature.