Add CallbackDispatchBody type hints to dispatch methods

Author: KoolADE85

dash/dash.py

@@ -81,7 +81,7 @@
     _import_layouts_from_pages,
 )
 from ._jupyter import jupyter_dash, JupyterDisplayMode
-from .types import RendererHooks
+from .types import CallbackDispatchBody, RendererHooks
 
 RouteCallable = Callable[..., Any]
 
@@ -1472,7 +1472,7 @@ def callback(self, *_args, **_kwargs) -> Callable[..., Any]:
         )
 
     # pylint: disable=R0915
-    def _initialize_context(self, body):
+    def _initialize_context(self, body: CallbackDispatchBody):
         """Initialize the global context for the request."""
         g = AttributeDict({})
         g.inputs_list = body.get("inputs", [])
@@ -1493,7 +1493,7 @@ def _initialize_context(self, body):
         g.updated_props = {}
         return g
 
-    def _prepare_callback(self, g, body):
+    def _prepare_callback(self, g, body: CallbackDispatchBody):
         """Prepare callback-related data."""
         output = body["output"]
         try: