feat: registry.has(); helpers to get all components and registries; access component from ext class (#1030)

* feat: registry.has(); helpers to get all components and registries; access component from ext class

* refactor: add missing import

CHANGELOG.md

@@ -28,6 +28,13 @@
 
     See the API reference for [`@djc_test`](https://django-components.github.io/django-components/0.131/reference/testing_api/#djc_test) for more details.
 
+- `ComponentRegistry` now has a `has()` method to check if a component is registered
+   without raising an error.
+
+- Get all created `Component` classes with `all_components()`.
+
+- Get all created `ComponentRegistry` instances with `all_registries()`.
+
 #### Refactor
 
 - The `startcomponent` and `upgradecomponent` commands are deprecated, and will be removed in v1.

docs/concepts/advanced/component_registry.md

@@ -80,6 +80,9 @@ registry.register("card", CardComponent)
 registry.all()  # {"button": ButtonComponent, "card": CardComponent}
 registry.get("card")  # CardComponent
 
+# Check if component is registered
+registry.has("button")  # True
+
 # Unregister single component
 registry.unregister("card")
 

docs/concepts/advanced/extensions.md

@@ -330,6 +330,51 @@ class MyComponent(Component):
 
 This will log the component name and color when the component is created, deleted, or rendered.
 
+### Utility functions
+
+django-components provides a few utility functions to help with writing extensions:
+
+- [`all_components()`](../../../reference/api#django_components.all_components) - returns a list of all created component classes.
+- [`all_registries()`](../../../reference/api#django_components.all_registries) - returns a list of all created registry instances.
+
+### Accessing the component class from within an extension
+
+When you are writing the extension class that will be nested inside a Component class, e.g.
+
+```py
+class MyTable(Component):
+    class MyExtension:
+        def some_method(self):
+            ...
+```
+
+You can access the owner Component class (`MyTable`) from within methods of the extension class (`MyExtension`) by using the `component_class` attribute:
+
+```py
+class MyTable(Component):
+    class MyExtension:
+        def some_method(self):
+            print(self.component_class)
+```
+
+Here is how the `component_class` attribute may be used with our `ColorLogger`
+extension shown above:
+
+```python
+class ColorLoggerExtensionClass(ComponentExtension.ExtensionClass):
+    color: str
+
+    def log(self, msg: str) -> None:
+        print(f"{self.component_class.name}: {msg}")
+
+
+class ColorLoggerExtension(ComponentExtension):
+    name = "color_logger"
+
+    # All `Component.ColorLogger` classes will inherit from this class.
+    ExtensionClass = ColorLoggerExtensionClass
+```
+
 ## Extension Commands
 
 Extensions in django-components can define custom commands that can be executed via the Django management command interface. This allows for powerful automation and customization capabilities.

docs/reference/api.md

@@ -155,6 +155,14 @@
     options:
       show_if_no_docstring: true
 
+::: django_components.all_components
+    options:
+      show_if_no_docstring: true
+
+::: django_components.all_registries
+    options:
+      show_if_no_docstring: true
+
 ::: django_components.autodiscover
     options:
       show_if_no_docstring: true

src/django_components/__init__.py

@@ -15,7 +15,7 @@ from django_components.util.command import (
     CommandSubcommand,
     ComponentCommand,
 )
-from django_components.component import Component, ComponentVars
+from django_components.component import Component, ComponentVars, all_components
 from django_components.component_media import ComponentMediaInput, ComponentMediaInputPath
 from django_components.component_registry import (
     AlreadyRegistered,
@@ -24,6 +24,7 @@ from django_components.component_registry import (
     RegistrySettings,
     register,
     registry,
+    all_registries,
 )
 from django_components.components import DynamicComponent
 from django_components.dependencies import render_dependencies
@@ -60,6 +61,8 @@ from django_components.util.types import EmptyTuple, EmptyDict
 
 
 __all__ = [
+    "all_components",
+    "all_registries",
     "AlreadyRegistered",
     "autodiscover",
     "BaseNode",

src/django_components/component.py

@@ -111,7 +111,7 @@ CssDataType = TypeVar("CssDataType", bound=Mapping[str, Any])
 
 # NOTE: `ReferenceType` is NOT a generic pre-3.9
 if sys.version_info >= (3, 9):
-    AllComponents = List[ReferenceType["Component"]]
+    AllComponents = List[ReferenceType[Type["Component"]]]
 else:
     AllComponents = List[ReferenceType]
 
@@ -120,6 +120,16 @@ else:
 ALL_COMPONENTS: AllComponents = []
 
 
+def all_components() -> List[Type["Component"]]:
+    """Get a list of all created [`Component`](../api#django_components.Component) classes."""
+    components: List[Type["Component"]] = []
+    for comp_ref in ALL_COMPONENTS:
+        comp = comp_ref()
+        if comp is not None:
+            components.append(comp)
+    return components
+
+
 @dataclass(frozen=True)
 class RenderInput(Generic[ArgsType, KwargsType, SlotsType]):
     context: Context

src/django_components/component_media.py

@@ -5,6 +5,7 @@ from copy import copy
 from dataclasses import dataclass
 from pathlib import Path
 from typing import TYPE_CHECKING, Any, Callable, Dict, List, Literal, Optional, Protocol, Tuple, Type, Union, cast
+from weakref import WeakKeyDictionary
 
 from django.contrib.staticfiles import finders
 from django.core.exceptions import ImproperlyConfigured
@@ -398,7 +399,11 @@ def _get_comp_cls_attr(comp_cls: Type["Component"], attr: str) -> Any:
     return None
 
 
-media_cache: Dict[Type["Component"], MediaCls] = {}
+# NOTE: We use weakref to avoid issues with lingering references.
+if sys.version_info >= (3, 9):
+    media_cache: WeakKeyDictionary[Type["Component"], MediaCls] = WeakKeyDictionary()
+else:
+    media_cache: WeakKeyDictionary = WeakKeyDictionary()
 
 
 def _get_comp_cls_media(comp_cls: Type["Component"]) -> Any:

src/django_components/component_registry.py

@@ -150,6 +150,18 @@ class InternalRegistrySettings(NamedTuple):
 ALL_REGISTRIES: AllRegistries = []
 
 
+def all_registries() -> List["ComponentRegistry"]:
+    """
+    Get a list of all created [`ComponentRegistry`](../api#django_components.ComponentRegistry) instances.
+    """
+    registries: List["ComponentRegistry"] = []
+    for reg_ref in ALL_REGISTRIES:
+        reg = reg_ref()
+        if reg is not None:
+            registries.append(reg)
+    return registries
+
+
 class ComponentRegistry:
     """
     Manages [components](../api#django_components.Component) and makes them available
@@ -201,7 +213,8 @@ class ComponentRegistry:
     registry.register("card", CardComponent)
     registry.all()
     registry.clear()
-    registry.get()
+    registry.get("button")
+    registry.has("button")
     ```
 
     # Using registry to share components
@@ -455,6 +468,29 @@ class ComponentRegistry:
 
         return self._registry[name].cls
 
+    def has(self, name: str) -> bool:
+        """
+        Check if a [`Component`](../api#django_components.Component)
+        class is registered under the given name.
+
+        Args:
+            name (str): The name under which the component was registered. Required.
+
+        Returns:
+            bool: `True` if the component is registered, `False` otherwise.
+
+        **Example:**
+
+        ```python
+        # First register component
+        registry.register("button", ButtonComponent)
+        # Then check
+        registry.has("button")
+        # > True
+        ```
+        """
+        return name in self._registry
+
     def all(self) -> Dict[str, Type["Component"]]:
         """
         Retrieve all registered [`Component`](../api#django_components.Component) classes.
@@ -563,6 +599,9 @@ registry.get("button")
 # Get all
 registry.all()
 
+# Check if component is registered
+registry.has("button")
+
 # Unregister single
 registry.unregister("button")
 

src/django_components/extension.py

@@ -103,6 +103,11 @@ class OnComponentDataContext(NamedTuple):
 
 
 class BaseExtensionClass:
+    """Base class for all extension classes."""
+
+    component_class: Type["Component"]
+    """The Component class that this extension is defined on."""
+
     def __init__(self, component: "Component") -> None:
         self.component = component
 
@@ -116,6 +121,10 @@ class ComponentExtension:
     Read more on [Extensions](../../concepts/advanced/extensions).
     """
 
+    ###########################
+    # USER INPUT
+    ###########################
+
     name: str
     """
     Name of the extension.
@@ -255,6 +264,10 @@ class ComponentExtension:
 
     urls: List[URLRoute] = []
 
+    ###########################
+    # Misc
+    ###########################
+
     def __init_subclass__(cls) -> None:
         if not cls.name.isidentifier():
             raise ValueError(f"Extension name must be a valid Python identifier, got {cls.name}")
@@ -532,7 +545,10 @@ class ExtensionManager:
                 bases: tuple[Type, ...] = (component_ext_subclass, ext_base_class)
             else:
                 bases = (ext_base_class,)
-            component_ext_subclass = type(ext_class_name, bases, {})
+
+            # Allow to extension class to access the owner `Component` class that via
+            # `ExtensionClass.component_class`.
+            component_ext_subclass = type(ext_class_name, bases, {"component_class": component_cls})
 
             # Finally, reassign the new class extension class on the component class.
             setattr(component_cls, ext_class_name, component_ext_subclass)

src/django_components/slots.py

@@ -56,9 +56,6 @@ class SlotFunc(Protocol, Generic[TSlotData]):
     def __call__(self, ctx: Context, slot_data: TSlotData, slot_ref: "SlotRef") -> SlotResult: ...  # noqa E704
 
 
-SlotContent = Union[SlotResult, SlotFunc[TSlotData], "Slot[TSlotData]"]
-
-
 @dataclass
 class Slot(Generic[TSlotData]):
     """This class holds the slot content function along with related metadata."""
@@ -100,6 +97,11 @@ class Slot(Generic[TSlotData]):
         return f"<{self.__class__.__name__} component_name={comp_name} slot_name={slot_name}>"
 
 
+# NOTE: This must be defined here, so we don't have any forward references
+# otherwise Pydantic has problem resolving the types.
+SlotContent = Union[SlotResult, SlotFunc[TSlotData], Slot[TSlotData]]
+
+
 # Internal type aliases
 SlotName = str
 

src/django_components/util/testing.py

@@ -265,7 +265,7 @@ def djc_test(
     """  # noqa: E501
 
     def decorator(func: Callable) -> Callable:
-        if isinstance(func, type):
+        if isinstance(func, type) and func.__name__.lower().startswith("test"):
             # If `djc_test` is applied to a class, we need to apply it to each test method
             # individually.
             # The rest of this function addresses `func` being a function

tests/test_component.py

@@ -26,7 +26,7 @@ from django.urls import path
 from django.utils.safestring import SafeString
 from pytest_django.asserts import assertHTMLEqual, assertInHTML
 
-from django_components import Component, ComponentView, Slot, SlotFunc, register, types
+from django_components import Component, ComponentView, Slot, SlotFunc, all_components, register, types
 from django_components.slots import SlotRef
 from django_components.urls import urlpatterns as dc_urlpatterns
 
@@ -1497,3 +1497,28 @@ class TestComponentHook:
         assert context_in_before == context_in_after
         assert "from_on_before" in context_in_before  # type: ignore[operator]
         assert "from_on_after" in context_in_after  # type: ignore[operator]
+
+
+@djc_test
+class TestComponentHelpers:
+    def test_all_components(self):
+        # NOTE: When running all tests, this list may already have some components
+        # as some components in test files are defined on module level, outside of
+        # `djc_test` decorator.
+        all_comps_before = len(all_components())
+
+        # Components don't have to be registered to be included in the list
+        class TestComponent(Component):
+            template: types.django_html = """
+                Hello from test
+            """
+
+        assert len(all_components()) == all_comps_before + 1
+
+        @register("test2")
+        class Test2Component(Component):
+            template: types.django_html = """
+                Hello from test2
+            """
+
+        assert len(all_components()) == all_comps_before + 2

tests/test_extension.py

@@ -106,7 +106,7 @@ class DummyNestedExtension(ComponentExtension):
 
 
 def with_component_cls(on_created: Callable):
-    class TestComponent(Component):
+    class TempComponent(Component):
         template = "Hello {{ name }}!"
 
         def get_context_data(self, name="World"):
@@ -124,11 +124,27 @@ def with_registry(on_created: Callable):
 @djc_test
 class TestExtension:
     @djc_test(components_settings={"extensions": [DummyExtension]})
-    def test_extensios_setting(self):
+    def test_extensions_setting(self):
         assert len(app_settings.EXTENSIONS) == 2
         assert isinstance(app_settings.EXTENSIONS[0], ViewExtension)
         assert isinstance(app_settings.EXTENSIONS[1], DummyExtension)
 
+    @djc_test(components_settings={"extensions": [DummyExtension]})
+    def test_access_component_from_extension(self):
+        class TestAccessComp(Component):
+            template = "Hello {{ name }}!"
+
+            def get_context_data(self, arg1, arg2, name="World"):
+                return {"name": name}
+
+        ext_class = TestAccessComp.TestExtension  # type: ignore[attr-defined]
+        assert issubclass(ext_class, ComponentExtension.ExtensionClass)
+        assert ext_class.component_class is TestAccessComp
+
+        # NOTE: Required for test_component_class_lifecycle_hooks to work
+        del TestAccessComp
+        gc.collect()
+
 
 @djc_test
 class TestExtensionHooks:
@@ -147,7 +163,7 @@ class TestExtensionHooks:
 
             # Verify on_component_class_created was called
             assert len(extension.calls["on_component_class_created"]) == 1
-            assert extension.calls["on_component_class_created"][0] == "TestComponent"
+            assert extension.calls["on_component_class_created"][0] == "TempComponent"
 
         # Create a component class in a separate scope, to avoid any references from within
         # this test function, so we can garbage collect it after the function returns
@@ -158,8 +174,11 @@ class TestExtensionHooks:
         gc.collect()
 
         # Verify on_component_class_deleted was called
-        assert len(extension.calls["on_component_class_deleted"]) == 1
-        assert extension.calls["on_component_class_deleted"][0] == "TestComponent"
+        # NOTE: The previous test, `test_access_component_from_extension`, is sometimes
+        # garbage-collected too late, in which case it's included in `on_component_class_deleted`.
+        # So in the test we check only for the last call.
+        assert len(extension.calls["on_component_class_deleted"]) >= 1
+        assert extension.calls["on_component_class_deleted"][-1] == "TempComponent"
 
     @djc_test(components_settings={"extensions": [DummyExtension]})
     def test_registry_lifecycle_hooks(self):

tests/test_registry.py

@@ -9,6 +9,7 @@ from django_components import (
     NotRegistered,
     RegistrySettings,
     TagProtectedError,
+    all_registries,
     component_formatter,
     component_shorthand_formatter,
     register,
@@ -39,14 +40,18 @@ class MockComponentView(Component):
 @djc_test
 class TestComponentRegistry:
     def test_register_class_decorator(self):
+        assert not registry.has("decorated_component")
+
         @register("decorated_component")
         class TestComponent(Component):
             pass
 
+        assert registry.has("decorated_component")
         assert registry.get("decorated_component") == TestComponent
 
         # Cleanup
         registry.unregister("decorated_component")
+        assert not registry.has("decorated_component")
 
     def test_register_class_decorator_custom_registry(self):
         my_lib = Library()
@@ -245,3 +250,18 @@ class TestProtectedTags:
 
         # Cleanup
         registry.unregister("sth_else")
+
+
+@djc_test
+class TestRegistryHelpers:
+    def test_all_registries(self):
+        # Default registry
+        assert len(all_registries()) == 1
+
+        reg = ComponentRegistry()
+
+        assert len(all_registries()) == 2
+
+        del reg
+
+        assert len(all_registries()) == 1