declarative.rst

Declarative container

.. currentmodule:: dependency_injector.containers

:py:class:`DeclarativeContainer` is a class-based style of the providers definition.

You create the declarative container subclass, put the providers as attributes and create the container instance.

.. literalinclude:: ../../examples/containers/declarative.py
   :language: python
   :lines: 3-

The declarative container providers should only be used when you have the container instance. Working with the providers of the container on the class level will influence all further instances.

A declarative container cannot have any methods or attributes other than providers.

The container class provides next attributes:

• providers - the dictionary of all the container providers
• cls_providers - the dictionary of the container providers of the current container
• inherited_providers - the dictionary of all the inherited container providers

.. literalinclude:: ../../examples/containers/declarative_inheritance.py
   :language: python
   :lines: 3-

Injections in the declarative container are done the usual way:

.. literalinclude:: ../../examples/containers/declarative_injections.py
   :language: python
   :lines: 3-

You can override container providers while creating a container instance:

.. literalinclude:: ../../examples/containers/declarative_override_providers.py
   :language: python
   :lines: 3-
   :emphasize-lines: 13

Alternatively, you can call container.override_providers() method when the container instance already exists:

container = Container()

container.override_providers(foo=mock.Mock(Foo), bar=mock.Mock(Bar))

assert isinstance(container.foo(), mock.Mock)
assert isinstance(container.bar(), mock.Mock)

You can also use container.override_providers() with a context manager to reset provided overriding after the context is closed:

container = Container()

with container.override_providers(foo=mock.Mock(Foo), bar=mock.Mock(Bar)):
    assert isinstance(container.foo(), mock.Mock)
    assert isinstance(container.bar(), mock.Mock)

assert isinstance(container.foo(), Foo)
assert isinstance(container.bar(), Bar)

.. disqus::