Register elements

The domain object is used by the domain's elements to register themselves with the domain.

With decorators

from protean import Domain
from protean.fields import Integer, String

domain = Domain(__file__)


@domain.aggregate
class User:
    first_name = String(max_length=50)
    last_name = String(max_length=50)
    age = Integer()

A full list of domain decorators along with examples are available in the decorators section.

Passing additional options

There might be additional options you will pass in a Meta inner class, depending upon the element being registered.

from protean import Domain
from protean.fields import Integer, String

domain = Domain(__file__)


@domain.aggregate(stream_category="account")
class User:
    first_name = String(max_length=50)
    last_name = String(max_length=50)
    age = Integer()

In the above example, the User aggregate's default stream category user is customized to account.

Review the object model to understand multiple ways to pass these options. Refer to each domain element's documentation to understand the additional options supported by that element.

Explicit registration

You can also choose to register elements manually.

from protean.core.aggregate import BaseAggregate
from protean.domain import Domain
from protean.fields import Integer, String

domain = Domain(__file__)


class User(BaseAggregate):
    first_name = String(max_length=50)
    last_name = String(max_length=50)
    age = Integer()


domain.register(User, stream_category="account")

Note that the User class has been subclassed from BaseAggregate. That is how Protean understands the kind of domain element being registered. Each type of element in Protean has a distinct base class of its own.

Also, additional options are now passed in the register call to the domain.