nameko-autocrud

• A (slightly magical) dependency to automatically add CRUD RPC entrypoints to nameko microservices.
• Based on Sqlalchemy models.
• The aim is to reduce the amount of code required to implement common methods.
• Uses sqlalchemy-filters.
• Works in conjunction with sqlalchemy dependency providers such as nameko-sqlalchemy.
• Each dependency also can be used in other methods to get/manipulate model instances.
• Customisable components.

Installation

Install from PyPI:

pip install nameko-autocrud

Usage

from nameko_sqlalchemy import DatabaseSession
from nameko_autocrud import AutoCrud

class MyService:

    name = 'my_service'
    session = DatabaseSession(models.Base)

    member_auto_crud = AutoCrud(
        session,
        model_cls=models.Member,
        get_method_name='get_member',
        list_method_name='list_members',
        page_method_name='page_members',
        count_method_name='count_members',
        create_method_name='create_member',
        update_method_name='update_member',
        delete_method_name='delete_member',
    )
    payment_auto_crud = AutoCrud(
        session,
        model_cls=models.Payment,
        get_method_name='get_payment',
        list_method_name='list_payments'
    )

    @rpc
    def my_entrypoint(self, value):
        return value + 1

This will automatically make the following additional RPC entrypoints available:

get_member(self, id_)
list_members(self, filters=None, offset=None, limit=None, order_by=None)
page_members(self, page_size, page_num, filters=None, order_by=None)
count_members(self, filters=None)
update_member(self, id_, data)
create_member(self, data)
delete_member(self, id_)
get_payment(self, id_)
list_payments(self, filters=None, offset=None, limit=None, order_by=None)

The dependencies themselves can be used to manipulate sqlalchemy objects within other code E.g.

@rpc
def copy_member_name(self, from_id, to_id):
    member = self.member_auto_crud.get(from_id)
    self.member_auto_crud.update(to_id, {'name': member.name})

Customizing

Setting method names

The *_method_name kwargs are used to declare the name of each crud method. Setting this value to None (or not providing the kwarg) will prevent the method from being generated.

cake_crud = AutoCrud(
    session, model_cls=models.Cake,
    delete_method_name='eat_cake',
    update_method_name=None,
)

Customizing serialization

TODO - marshmallow examples

RPC Decorator Overrides

By default each generated service rpc method is decorated with the standard nameko.rpc.rpc decorator. This can be overridden for all methods by supplying the rpc kwarg to AutoCrud. For example, if the service is making use of nameko-amqp-retry, then AutoCrud should be instantiated with rpc=nameko_amqp_retry.rpc.

The rpc decorator can be overridden for specific methods by supplying kwargs like get_rpc, list_rpc etc. This makes it possible to declare the expected_exceptions or sensitive_variables that may be required for a particular method. E.g.

from nameko.rpc import rpc
from nameko_sqlalchemy import DatabaseSession
from nameko_autocrud import AutoCrud, NotFound

class MyService:

    name = 'my_service'
    session = DatabaseSession(models.Base)

    cake_crud = AutoCrud(
        session, model_cls=models.Cake,
        get_method_name="get_cake",
        list_method_name="list_cakes",
        get_rpc=rpc(expected_exceptions=NotFound),
    )

Events

Nameko-autocrud includes an additional AutoCrudWithEvents DependencyProvider. This has the same behaviour as AutoCrud but can dispatch nameko events for create, update & delete actions.

from nameko.events import EventDispatcher
from nameko_sqlalchemy import DatabaseSession
from nameko_autocrud import AutoCrudWithEvents

class MyService:

    name = 'my_service'
    session = DatabaseSession(models.Base)
    dispatcher = EventDispatcher()

    payment_auto_crud = AutoCrudWithEvents(
        session, dispatcher, 'payment',
        model_cls=models.Payment,
        create_event_name='payment_created',
        update_event_name='payment_updated',
        delete_event_name='payment_deleted',
        create_method_name='create_payment',
        update_method_name='update_payment',
        delete_method_name='delete_payment',
    )

Nameko events will be generated for every *_even_name parameter given. If the parameter is set to None or not present, the event will not be dispatched.

Create events

Create events will be dispatched after a successful creation. The event-name is given by create_event_name and the payload will be of the form:

{
    'payment': {<serialized payment instance after creation>}
}

Where the payment key is given by the required event_entity_name parameter.

Update events

Update events will be dispatched after a successful update that resulted in changes. The event-name is given by update_event_name and the payload will be of the form:

{
  'payment': {<serialized payment instance after the update>},
  'changed': [<list of the changed fields>],
  'before': {<serialized payment instance before the update>},
}

Where the payment key is given by the required event_entity_name parameter.

Delete events

Delete events will be dispatched after a successful deletion. The event-name is given by delete_event_name and the payload will be of the form:

{
    'payment': {<serialized payment instance before deletion>}
}

Where the payment key is given by the required event_entity_name parameter.

TODO - Specifying event serializer