ditainer 1.1.0

Dependency Injection Container for Python

Dependency Inection Container for Python

This is a basic Dependency Inection Container for Python.

How to use it

At the moment, ditainer can only load dependencies from yaml files.

A dependency is treated as a service. A service is a class and could receive arguments to be initialized. It is also possible to initialize a class through its factory, which may also require arguments. Additionally, a service can be tagged.

Types of arguments:

• Simple. Just the literal argument.
• A reference to another service. The prefix !ref followed by the id of the other service.
• All services tagged with a specific tag. The prefix !tagged followed by the tag.

An example of yaml file could be:

services:
  - id: DBSession
    module: my_module.db
    class: DBSession
    factory: create_session

  - id: UserRepository
    module: my_module.user.repository
    class: MySqlUserRepository
    arguments:
      - !ref DBSession

  - id: QueryBus
    module: my_module.query_bus
    class: InMemoryQueryBus
    arguments:
      - !tagged query_handler

  - id: UserFindByIDQueryHandler
    module: my_module.user.find_by_id_query_handler
    class: UserFindByIDQueryHandler
    arguments:
      - !ref UserRepository
    tags:
      - query_handler

  - id: UserFindByCodeQueryHandler
    module: my_module.user.find_by_code_query_handler
    class: UserFindByCodeQueryHandler
    arguments:
      - !ref UserRepository
    tags:
      - query_handler

Each service must have id, module and class. If the service has no id, module or class, there will be an error.

ditainer can also understand an import file with different files to load:

imports:
  - { resource: "./services_1.yaml" }
  - { resource: "./services_2.yaml" }
  - { resource: "./services_3.yaml" }

Start using ditainer

Once the yaml files are ready:

import os

from ditainer.container import Container
from ditainer.loader import YAMLLoader


container = Container()
loader = YAMLLoader(container)
loader.load(os.path.join(os.path.dirname(__file__), "imports.yaml"))

from my_module import container
from my_module.user import User
from my_module.user.find_by_id_query import UserFindByIdQuery

def get_user() -> User:
  query_bus = container.find("QueryBus")
  query = UserFindByIdQuery(123)

  user = query_bus.ask(query)
  return user

It is also possible to find services by tags:

from my_module import container
from my_module.user import User
from my_module.user.find_by_id_query import UserFindByIdQuery


query_handlers = container.find_tagged("query_handler")

You can find more examples in the tests folder.

Based on: https://www.npmjs.com/package/node-dependency-injection