How to atomically update one document with sort, and return the result?

[TheBloke]

Hi all

I would like to do the following:

Atomically update the least used row in a collection, both returning the document and updating its last_updated (datetime) field to the current datetime

Example document model:

class LAccount(Document):
    last_used: Annotated[Optional[datetime], Indexed(index_type=ASCENDING)] = Field(default=None)
    valid: Optional[bool] = Field(default=None)

I want to do something like:

result = LAccount.find(LAccount.valid == True).sort("+last_used").update(
    {"$set": {LAccount.last_used: datetime.utcnow()}}
)
the_updated_document = await result.to_list()[0]

Or:

await MAccount.find(MAccount.llm_type == "openai").sort("+last_used").limit(1).set(
    {LAccount.last_used: datetime.utcnow()}
).to_list()

But neither is valid

I have read through the tutorial and the API docs and I can't find any way to do this at the moment.

Is it possible to do this in one operation? I need to do this atomically, because I will have hundreds of concurrent async operations working on the same collection.

Thanks in advance!