Fix `Container` provider to apply context overridings on root container initialization

docs/main/changelog.rst

@@ -9,6 +9,9 @@ follows `Semantic versioning`_
 
 Development version
 -------------------
+- Fix ``Container`` provider to apply context overridings on root container initialization.
+  See issue `#354 <https://github.com/ets-labs/python-dependency-injector/issues/354>`_.
+  Many thanks to `Shaun Cutts <https://github.com/shaunc>`_ for submitting the issue.
 - Hotfix for version ``4.8.0``: fix side effect in ``Container`` provider overriding.
 
 4.8.1

src/dependency_injector/containers.pyx

@@ -15,6 +15,7 @@ from .providers cimport (
     Provider,
     Object,
     Resource,
+    Container as ContainerProvider,
     deepcopy,
 )
 
@@ -252,6 +253,13 @@ class DynamicContainer(object):
         if futures:
             return asyncio.gather(*futures)
 
+    def apply_container_providers_overridings(self):
+        """Apply container providers' overridings."""
+        for provider in self.providers.values():
+            if not isinstance(provider, ContainerProvider):
+                continue
+            provider.apply_overridings()
+
 
 class DeclarativeContainerMetaClass(type):
     """Declarative inversion of control container meta class."""
@@ -407,6 +415,7 @@ class DeclarativeContainer(object):
         container.declarative_parent = cls
         container.set_providers(**deepcopy(cls.providers))
         container.override_providers(**overriding_providers)
+        container.apply_container_providers_overridings()
         return container
 
     @classmethod

src/dependency_injector/providers.pyx

@@ -765,10 +765,7 @@ cdef class DependenciesContainer(Object):
     cpdef object _override_providers(self, object container):
         """Override providers with providers from provided container."""
         for name, dependency_provider in container.providers.items():
-            provider = self.__providers.get(name)
+            provider = getattr(self, name)
-
-            if not provider:
-                continue
 
             if provider.last_overriding is dependency_provider:
                 continue
@@ -3041,7 +3038,6 @@ cdef class Container(Provider):
 
         if container is None:
             container = container_cls()
-            container.override_providers(**overriding_providers)
         self.__container = container
 
         super(Container, self).__init__()
@@ -3085,6 +3081,13 @@ cdef class Container(Provider):
         self.__container.override_providers(**provider.providers)
         super().override(provider)
 
+    def apply_overridings(self):
+        """Apply container overriding.
+
+        This method should not be called directly. It is called on
+        declarative container initialization."""
+        self.__container.override_providers(**self.__overriding_providers)
+
     cpdef object _provide(self, tuple args, dict kwargs):
         """Return single instance."""
         return self.__container

tests/unit/providers/test_container_py2_py3.py

@@ -76,3 +76,21 @@ class ContainerTests(unittest.TestCase):
 
         with self.assertRaises(errors.Error):
             provider.override(providers.Object('foo'))
+
+    def test_lazy_overriding(self):
+        class D(containers.DeclarativeContainer):
+            foo = providers.Object("foo")
+
+        class A(containers.DeclarativeContainer):
+            d = providers.DependenciesContainer()
+            bar = providers.Callable(lambda f: f + "++", d.foo.provided)
+
+        class B(containers.DeclarativeContainer):
+            d = providers.DependenciesContainer()
+
+            a = providers.Container(A, d=d)
+
+        b = B(d=D())
+        result = b.a().bar()
+        self.assertEqual(result, 'foo++')
+        # See: https://github.com/ets-labs/python-dependency-injector/issues/354