Support Inheritance

[mcleantom]

Feature request

Context

My previous models all have fields such as _date_created which I would like to support by having a base document model such as:

class BaseMongoModel(Model):
    date_created: datetime = Field(default_factory=datetime.utcnow)


class Tree(BaseMongoModel):
    name: str
    average_size: float
    discovery_year: int

However when trying to apply something with the engine, I get the error:

TypeError: Can only call find with a Model class

Solution

Implement a base model class and allow inheritance

Alternative solutions

This could be solved using composition, such as:

class Metadata(EmbeddedModel):
    date_created: datetime = Field(default_factory=datetime.utcnow)


class Tree(Model):
    metadata: Metadata = Field(default_factory=Metadata)
    name: str
    average_size: float
    discovery_year: int

However for this use case, I think I would prefer inheritance to ensure that all new models have this data.