fix: use the Route.component for the real component

Before we put the internal RenderPage component in the Route.component.
This was not only confusing, but also left no room for using this
field for other purposes, such as using this for a custom Markdown
component.

solara/autorouting.py

@@ -123,15 +123,14 @@ def get_nav_widget():
 @solara.component
 def RenderPage(main_name: str = "Page"):
     """Renders the page that matches the route."""
-    level_start = solara.use_route_level()
     router = solara.use_context(solara.routing.router_context)
     # we use these to cache script runs that use regular ipywidgets
     modules = cast(Dict[str, ModuleType], solara.use_memo(dict, dependencies=[]))
-    modules_modified_times = solara.use_memo(dict, dependencies=[])
+    modules_modified_times = cast(Dict[str, float], solara.use_memo(dict, dependencies=[]))
 
-    if len(router.path_routes) <= level_start:
+    if not router.path_routes:
         with solara.VBox() as main:
-            solara.Error(f"Page not found: {router.path}, len(router.path_routes)={len(router.path_routes)} <= level_start={level_start}")
+            solara.Error(f"Page not found: {router.path}")
             parent = "/" + "/".join(router.parts[:-1])
             with solara.Link(parent):
                 solara.Button(f"Go to parent: {parent}", text=True)
@@ -144,10 +143,9 @@ def RenderPage(main_name: str = "Page"):
                     pp(router.routes)
         return main
 
-    level_max = level_start
     layouts = []  # nested layouts
-    # find the 'RenderPage' sentinel value to find the deepest level we should render
-    for level in range(level_start, len(router.path_routes)):
+    level_max = len(router.path_routes) - 1
+    for level in range(level_max + 1):
         # we always level_start the 'package'/'root' layout
         roots = [k for k in router.path_routes_siblings[level] if k.path == "/"]
         if len(roots) == 1:
@@ -158,8 +156,12 @@ def RenderPage(main_name: str = "Page"):
         # and, if not the root layout, include the layout for the current route
         if route.path != "/" and route.layout:
             layouts.append(route.layout)
-        if route.component is RenderPage:
-            level_max = level
+        # used in for example the docs for use_route, only the route path are specified,
+        # nothing else, which means we will not follow that route path, but limit it to rendering
+        # router.path_routes[level_max] instead. It's assumed that component (Page) will continue
+        # handling the rest of the routing
+        if route.data is None and route.module is None and route.component is None:
+            level_max = level - 1
     route_current = router.path_routes[level_max]
     routes_siblings = router.path_routes_siblings[level_max]
     routes_siblings_index = routes_siblings.index(route_current)
@@ -224,9 +226,6 @@ def get_args(f):
         title_element = solara.Title(title)
         module = None
         Page = route_current.component
-        # translate the default RenderPage as no value given (None)
-        if Page is RenderPage:
-            Page = None
         if route_current.module is not None and (Page is None):
             # if not a custom component is given, we try to find a Page component
             # in the module
@@ -239,9 +238,6 @@ def get_args(f):
                 Page = namespace.get("page", namespace.get("app", Page))
                 Page = nested_get(namespace, main_name, Page)
 
-        if Page is None and route_current.children:
-            # we we did not get a component, but we recursively render
-            Page = RenderPage
         if isinstance(Page, ipywidgets.Widget):
             # If we have a widget, we need to execute this again for each
             # connection, since we cannot share widgets between connections/users.
@@ -291,12 +287,12 @@ def get_args(f):
             main = wrap_in_layouts(main, layouts)
         else:
             if route_current.module:
-                path = route_current.module.__file__
+                path_str = route_current.module.__file__
                 local_scope = route_current.module.__dict__
                 ignore = ["display"]
                 options = [k for k in list(local_scope) if k not in ignore and not k.startswith("_")]
                 matches = difflib.get_close_matches(main_name, options)
-                msg = f"No object with name {main_name} found for {path}"
+                msg = f"No object with name {main_name} found for {path_str}"
                 if matches:
                     msg += " Did you mean: " + " or ".join(map(repr, matches))
                 else:
@@ -397,7 +393,9 @@ def generate_routes(module: ModuleType) -> List[solara.Route]:
         title = get_title(module)
         children = getattr(module, "routes", [])
         if hasattr(module, "Page"):
-            routes.append(solara.Route(path="/", component=RenderPage, data=module, module=module, layout=layout, children=children, label=title, file=file))
+            routes.append(
+                solara.Route(path="/", component=get_page(module), data=module, module=module, layout=layout, children=children, label=title, file=file)
+            )
 
         assert module.__file__ is not None
         reload.reloader.watcher.add_file(module.__file__)
@@ -411,7 +409,9 @@ def generate_routes(module: ModuleType) -> List[solara.Route]:
             # however, this may break things.
             # name = name.replace("_", "-")
             if info.ispkg:
-                route = solara.Route(name, component=RenderPage, children=generate_routes(submod), module=submod, layout=None, label=title)
+                route = solara.Route(
+                    name, component=get_page(submod, required=False), children=generate_routes(submod), module=submod, layout=None, label=title
+                )
                 # skip empty subpackages
                 if len(route.children) == 0:
                     continue
@@ -423,7 +423,9 @@ def generate_routes(module: ModuleType) -> List[solara.Route]:
                 if subfile:
                     children = fix_routes(children, subfile)
                 module_layout = getattr(submod, "Layout", None)
-                route = solara.Route(name, component=RenderPage, module=submod, layout=module_layout, children=children, label=title, file=subfile)
+                route = solara.Route(
+                    name, component=get_page(submod, required=False), module=submod, layout=module_layout, children=children, label=title, file=subfile
+                )
             routes.append(route)
         if route_order:
             lookup = {k.path: k for k in routes}
@@ -442,9 +444,20 @@ def generate_routes(module: ModuleType) -> List[solara.Route]:
             root = get_root(children)
             if layout is not None and root is not None and root.layout is None:
                 warnings.warn(f'You defined routes in {file}, in this case, layout should be set on the root route (with path="/"), not on the module level')
-                children = fix_routes(children, file, layout)
                 layout = None
-        return [solara.Route(path="/", component=RenderPage, data=None, module=module, label=get_title(module), layout=layout, children=children, file=file)]
+        children = fix_routes(children, file, layout)
+        return [
+            solara.Route(
+                path="/",
+                component=get_page(module, required=False),
+                data=None,
+                module=module,
+                label=get_title(module),
+                layout=layout,
+                children=children,
+                file=file,
+            )
+        ]
 
     return routes
 
@@ -501,8 +514,7 @@ def _generate_route_path(subpath: Path, layout=None, first=False, has_index=Fals
         route_path = "/"
     else:
         route_path = "-".join([k.lower() for k in title_parts])
-    # used as a 'sentinel' to find the deepest level of the route tree we need to render in 'RenderPage'
-    component = RenderPage
+    component = None
     children: List[solara.Route] = []
     module: Optional[ModuleType] = None
     data: Any = None
@@ -517,14 +529,20 @@ def _generate_route_path(subpath: Path, layout=None, first=False, has_index=Fals
         module = source_to_module(subpath, initial_namespace=initial_namespace)
         title = get_title(module)
         layout = getattr(module, "Layout", module_layout)
+        root = get_root(children)
         if hasattr(module, "routes"):
             children = getattr(module, "routes", [])
             root = get_root(children)
             if layout is not None and root is not None and root.layout is None:
                 warnings.warn(f'You defined routes in {subpath}, in this case, layout should be set on the root route (with path="/"), not on the module level')
-                children = fix_routes(children, subpath, layout)
                 layout = None
-        children = fix_routes(children, subpath)
+        children = fix_routes(children, subpath, layout)
+        component = get_page(module, required=False)
+        if root and component and root.component and component is not root.component:
+            warnings.warn(
+                f"In {subpath}, you defined a Page component, but also a component on the root route (with path='/') "
+                "which is not equal to the Page component at the module level. This is not recommended."
+            )
     route = solara.Route(route_path, component=component, module=module, label=title, children=children, data=data, layout=layout, file=subpath)
     return route
 

solara/server/app.py

@@ -1,3 +1,4 @@
+import dataclasses
 import importlib.util
 import logging
 import os
@@ -15,6 +16,7 @@
 from reacton.core import Element, render
 
 import solara
+from solara.util import nested_get
 
 from . import kernel_context, patch, reload, settings
 from .kernel import Kernel
@@ -149,6 +151,8 @@ def add_path():
                 mod = importlib.import_module(self.name)
                 routes = solara.generate_routes(mod)
 
+        app = solara.autorouting.RenderPage(self.app_name)
+
         # when the root moduled defined routes, skip the enclosing route object
         if len(routes) == 1 and routes[0].module and hasattr(routes[0].module, "routes"):
             if routes[0].component:
@@ -158,7 +162,13 @@ def add_path():
                 )
             routes = routes[0].children
 
-        app = solara.autorouting.RenderPage(self.app_name)
+        if self.app_name != "Page":
+            # if we specified the app name, we replace the component
+            if len(routes) > 1:
+                raise ValueError(f"App {self.name} has multiple routes, but a default app name was given: {self.app_name}")
+            assert len(routes) == 1
+            component = nested_get(routes[0].module.__dict__, self.app_name, None)
+            routes = [dataclasses.replace(routes[0], component=component)]
 
         if settings.ssg.build_path is None:
             settings.ssg.build_path = self.directory.parent.resolve() / "build"