feat: extensions (#1009)

* feat: extensions

* refactor: remove support for passing in extensions as instances

src/django_components/extensions/view.py

@@ -0,0 +1,80 @@
+from typing import TYPE_CHECKING, Any, Protocol, cast
+
+from django.http import HttpRequest, HttpResponse
+from django.views.generic import View
+
+from django_components.extension import BaseExtensionClass, ComponentExtension
+
+if TYPE_CHECKING:
+    from django_components.component import Component
+
+
+class ViewFn(Protocol):
+    def __call__(self, request: HttpRequest, *args: Any, **kwargs: Any) -> Any: ...  # noqa: E704
+
+
+class ComponentView(BaseExtensionClass, View):
+    """
+    Subclass of `django.views.View` where the `Component` instance is available
+    via `self.component`.
+    """
+
+    # NOTE: This attribute must be declared on the class for `View.as_view()` to allow
+    # us to pass `component` kwarg.
+    component = cast("Component", None)
+
+    def __init__(self, component: "Component", **kwargs: Any) -> None:
+        BaseExtensionClass.__init__(self, component)
+        View.__init__(self, **kwargs)
+
+    # NOTE: The methods below are defined to satisfy the `View` class. All supported methods
+    # are defined in `View.http_method_names`.
+    #
+    # Each method actually delegates to the component's method of the same name.
+    # E.g. When `get()` is called, it delegates to `component.get()`.
+
+    def get(self, request: HttpRequest, *args: Any, **kwargs: Any) -> HttpResponse:
+        component: "Component" = self.component
+        return getattr(component, "get")(request, *args, **kwargs)
+
+    def post(self, request: HttpRequest, *args: Any, **kwargs: Any) -> HttpResponse:
+        component: "Component" = self.component
+        return getattr(component, "post")(request, *args, **kwargs)
+
+    def put(self, request: HttpRequest, *args: Any, **kwargs: Any) -> HttpResponse:
+        component: "Component" = self.component
+        return getattr(component, "put")(request, *args, **kwargs)
+
+    def patch(self, request: HttpRequest, *args: Any, **kwargs: Any) -> HttpResponse:
+        component: "Component" = self.component
+        return getattr(component, "patch")(request, *args, **kwargs)
+
+    def delete(self, request: HttpRequest, *args: Any, **kwargs: Any) -> HttpResponse:
+        component: "Component" = self.component
+        return getattr(component, "delete")(request, *args, **kwargs)
+
+    def head(self, request: HttpRequest, *args: Any, **kwargs: Any) -> HttpResponse:
+        component: "Component" = self.component
+        return getattr(component, "head")(request, *args, **kwargs)
+
+    def options(self, request: HttpRequest, *args: Any, **kwargs: Any) -> HttpResponse:
+        component: "Component" = self.component
+        return getattr(component, "options")(request, *args, **kwargs)
+
+    def trace(self, request: HttpRequest, *args: Any, **kwargs: Any) -> HttpResponse:
+        component: "Component" = self.component
+        return getattr(component, "trace")(request, *args, **kwargs)
+
+
+class ViewExtension(ComponentExtension):
+    """
+    This extension adds a nested `View` class to each `Component`.
+    This nested class is a subclass of `django.views.View`, and allows the component
+    to be used as a view by calling `ComponentView.as_view()`.
+
+    This extension is automatically added to all components.
+    """
+
+    name = "view"
+
+    ExtensionClass = ComponentView