Add container dependencies concept

examples/miniapps/applications/example/core/containers.py

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+"""Containers module."""
+
+import six
+
+from dependency_injector import containers
+
+from core import providers
+
+
+class DeclarativeContainer(containers.DeclarativeContainer):
+    """Declarative container."""
+
+    def __new__(cls, **dependencies):
+        """Constructor.
+
+        :return: Dynamic container with copy of all providers.
+        :rtype: :py:class:`DynamicContainer`
+        """
+        # Make copy of declarative container providers for container instance
+        container_providers = providers.deepcopy(cls.providers)
+
+        # Fetch container dependencies
+        container_dependencies = dict()
+        for name, provider in six.iteritems(container_providers):
+            if isinstance(provider, providers.Dependency):
+                container_dependencies[name] = provider
+
+        # Satisfy container dependencies
+        for name, dependency in six.iteritems(container_dependencies):
+            try:
+                dependency_provider = dependencies[name]
+            except KeyError:
+                raise Exception('Dependency {name} of container {container} '
+                                'is not satisfied'.format(
+                                    name=name, container=cls))
+            else:
+                dependency.provided_by(dependency_provider)
+
+        # Create dynamic container
+        container = cls.instance_type()
+        container.provider_type = cls.provider_type
+        for name, provider in six.iteritems(container_providers):
+            setattr(container, name, provider)
+
+        return container

examples/miniapps/applications/example/core/providers.py

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+"""Providers module."""
+
+from dependency_injector import providers
+
+
+Factory = providers.Factory
+Singleton = providers.Singleton
+
+
+deepcopy = providers.deepcopy
+
+
+class Dependency(providers.ExternalDependency):
+    """Dependency provider."""
+
+    def __init__(self, type=object):
+        """Initializer."""
+        super(Dependency, self).__init__(type)

examples/miniapps/applications/example/main.py

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+"""Example applications."""
+
+from core import containers, providers
+
+from users import Users
+from photos import Photos
+
+
+class Core(containers.DeclarativeContainer):
+    """Core container."""
+
+    pgsql = providers.Singleton(object)
+    s3 = providers.Singleton(object)
+
+
+if __name__ == '__main__':
+    # Initializing containers
+    core = Core()
+    users = Users(database=core.pgsql)
+    photos = Photos(database=core.pgsql, file_storage=core.s3)
+
+    # Fetching few users
+    user_repository = users.user_repository()
+    user1 = user_repository.get(id=1)
+    user2 = user_repository.get(id=2)
+
+    # Making some checks
+    assert user1.id == 1
+    assert user2.id == 2
+    assert user_repository.db is core.pgsql()

examples/miniapps/applications/example/photos/__init__.py

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+"""Photos package."""
+
+from core import containers
+from core import providers
+
+from . import entities
+from . import repositories
+
+
+class Photos(containers.DeclarativeContainer):
+    """Photos package container."""
+
+    database = providers.Dependency()
+    file_storage = providers.Dependency()
+
+    photo = providers.Factory(entities.Photo)
+    photo_repository = providers.Singleton(repositories.PhotoRepository,
+                                           object_factory=photo.provider,
+                                           fs=file_storage,
+                                           db=database)

examples/miniapps/applications/example/photos/entities.py

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+class Photo(object):
+    pass

examples/miniapps/applications/example/photos/repositories.py

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+class PhotoRepository(object):
+
+    def __init__(self, object_factory, fs, db):
+        self.object_factory = object_factory
+        self.fs = fs
+        self.db = db

examples/miniapps/applications/example/users/__init__.py

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+"""Users package."""
+
+from core import containers
+from core import providers
+
+from . import entities
+from . import repositories
+
+
+class Users(containers.DeclarativeContainer):
+    """Users container."""
+
+    database = providers.Dependency()
+
+    user = providers.Factory(entities.User)
+    user_repository = providers.Singleton(repositories.UserRepository,
+                                          object_factory=user.provider,
+                                          db=database)

examples/miniapps/applications/example/users/entities.py

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+class User(object):
+
+    def __init__(self, id):
+        self.id = id

examples/miniapps/applications/example/users/repositories.py

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+class UserRepository(object):
+
+    def __init__(self, object_factory, db):
+        self.object_factory = object_factory
+        self.db = db
+
+    def get(self, id):
+        return self.object_factory(id=id)