Auto increment field

[humbertogontijo]

Is it possible to create a auto incremental field with beanie? If so, how to?
A short unique identifier also works

[gsakkis]

Here's what I use for auto increment documents:

from typing import ClassVar

import beanie
from beanie.odm.operators.update.general import Inc


class CounterDocument(beanie.Document):
    id: str
    n: int = 0

    class Settings:
        name = "counters"

    async def increment(self) -> int:
        await self.update(Inc({CounterDocument.n: 1}), upsert=True)
        return self.n


class AutoIncrementDocument(beanie.Document):
    id: int | None = None
    _counter: ClassVar[CounterDocument]

    @classmethod
    def set_collection(cls, collection):
        super().set_collection(collection)
        cls._counter = CounterDocument(id=collection.name)

    async def insert(self, **kwargs):
        if self.id is None:
            self.id = await self._counter.increment()
        return await super().insert(**kwargs)

    async def update(self, *args, **kwargs):
        if self.id is None:
            self.id = await self._counter.increment()
        return await super().update(*args, **kwargs)

It needs this fix, otherwise Beanie raises ValueError: Unknown annotation: int | None.

You can use it by simply subclassing your document from AutoIncrementDocument instead of beanie.Document:

class MyDocument(AutoIncrementDocument):
    name: str
    ...

async def init(database):
    await beanie.init_beanie(document_models=[CounterDocument, MyDocument], database=database)

[humbertogontijo]

I liked your approach. But I was looking for something like setting a type or value to a field instead of using the id field

[gsakkis]

Shouldn't be too hard to generalize it to make the field name a parameter instead of id, the rest remains the same.