Merge pull request #2771 from plotly/fix/namespace-package-map

Dynamic loading: map namespace to package name in case they differ.

Author: T4rk1n

dash/_callback.py

@@ -261,6 +261,7 @@ def insert_callback(
         "output": output,
         "raw_inputs": inputs,
         "manager": manager,
+        "allow_dynamic_callbacks": dynamic_creator,
     }
     callback_list.append(callback_spec)
 

dash/dash.py

@@ -806,7 +806,10 @@ def serve_reload_hash(self):
         )
 
     def serve_dist(self):
-        libraries = flask.request.get_json()
+        libraries = [
+            ComponentRegistry.namespace_to_package.get(lib, lib)
+            for lib in flask.request.get_json()
+        ]
         dists = []
         for dist_type in ("_js_dist", "_css_dist"):
             resources = ComponentRegistry.get_resources(dist_type, libraries)
@@ -1282,6 +1285,8 @@ def long_callback(
     def dispatch(self):
         body = flask.request.get_json()
 
+        nlibs = len(ComponentRegistry.registry)
+
         g = AttributeDict({})
 
         g.inputs_list = inputs = body.get(  # pylint: disable=assigning-non-slot
@@ -1311,6 +1316,7 @@ def dispatch(self):
 
         try:
             cb = self.callback_map[output]
+            _allow_dynamic = cb.get("allow_dynamic_callbacks", False)
             func = cb["callback"]
             g.background_callback_manager = (
                 cb.get("manager") or self._background_manager
@@ -1362,6 +1368,7 @@ def dispatch(self):
         except KeyError as missing_callback_function:
             msg = f"Callback function not found for output '{output}', perhaps you forgot to prepend the '@'?"
             raise KeyError(msg) from missing_callback_function
+
         ctx = copy_context()
         # noinspection PyArgumentList
         response.set_data(
@@ -1375,6 +1382,12 @@ def dispatch(self):
                 )
             )
         )
+
+        if not _allow_dynamic and nlibs != len(ComponentRegistry.registry):
+            print(
+                "Warning: component library imported during callback, move to top-level for full support.",
+                file=sys.stderr,
+            )
         return response
 
     def _setup_server(self):

dash/development/base_component.py

@@ -18,6 +18,7 @@ class ComponentRegistry:
 
     registry = OrderedSet()
     children_props = collections.defaultdict(dict)
+    namespace_to_package = {}
 
     @classmethod
     def get_resources(cls, resource_name, includes=None):
@@ -44,10 +45,12 @@ def __new__(mcs, name, bases, attributes):
             # as it doesn't have the namespace.
             return component
 
+        _namespace = attributes.get("_namespace", module)
+        ComponentRegistry.namespace_to_package[_namespace] = module
         ComponentRegistry.registry.add(module)
-        ComponentRegistry.children_props[attributes.get("_namespace", module)][
-            name
-        ] = attributes.get("_children_props")
+        ComponentRegistry.children_props[_namespace][name] = attributes.get(
+            "_children_props"
+        )
 
         return component