prevent embedded models from being created in a separate collection

[timgraham]

Models that are embedded generally shouldn't have their own collection. They can't be abstract because abstract models can't be instantiated and our syntax for creating objects with embedded models is:

Book.objects.create(
    author=Author(name="Shakespeare", age=55, address=Address(city="NYC", state="NY"))
)

Proposal:

• Create an EmbeddedModel class that overrides save() to raise NotSupportedError.
• The SchemaEditor will ignore EmbeddedModel subclasses.
• EmbeddedModel will use a custom manager that raises NotSupportedError for all QuerySet write operations.

[aclark4life]

@timgraham Re: custom manager, can that functionality go in the existing MongoManager?

[timgraham]

No, we don't want to prevent models that use MongoManager from be unwritable.

[aclark4life]

Oh, that's too bad. That means we'll probably want to rename MongoManager e.g.

• MongoManager -> RawAggregateManager

Then we can add EmbeddedModelManager and other managers as needed in the future.

[timgraham]

No, I am proposing a private manager that users won't interact with. We will keep all functionality that adds new queryset methods on MongoManager.