Allow to load pages from package

This allows to load the pages from an imported python package which is
recursively scanned. This is useful if one compiles an application using
Cython where the modules are then not .py files anymore, but compiled
.so files.

Author: rnestler

dash/_pages.py

@@ -1,6 +1,7 @@
 import collections
 import importlib
 import os
+import pkgutil
 import re
 import sys
 from fnmatch import fnmatch
@@ -411,6 +412,15 @@ def _page_meta_tags(app):
     ]
 
 
+def _ensure_layout_is_loaded(module_name, page_module):
+    if (
+        module_name in PAGE_REGISTRY
+        and not PAGE_REGISTRY[module_name]["supplied_layout"]
+    ):
+        _validate.validate_pages_layout(module_name, page_module)
+        PAGE_REGISTRY[module_name]["layout"] = getattr(page_module, "layout")
+
+
 def _import_layouts_from_pages(pages_folder):
     for root, dirs, files in os.walk(pages_folder):
         dirs[:] = [d for d in dirs if not d.startswith(".") and not d.startswith("_")]
@@ -428,10 +438,13 @@ def _import_layouts_from_pages(pages_folder):
             page_module = importlib.util.module_from_spec(spec)
             spec.loader.exec_module(page_module)
             sys.modules[module_name] = page_module
+            _ensure_layout_is_loaded(module_name, page_module)
 
-            if (
-                module_name in PAGE_REGISTRY
-                and not PAGE_REGISTRY[module_name]["supplied_layout"]
-            ):
-                _validate.validate_pages_layout(module_name, page_module)
-                PAGE_REGISTRY[module_name]["layout"] = getattr(page_module, "layout")
+
+def _import_layouts_from_package(pages_package):
+    modules = pkgutil.walk_packages(
+        pages_package.__path__, prefix=pages_package.__name__ + "."
+    )
+    for module in modules:
+        page_module = importlib.import_module(module.name)
+        _ensure_layout_is_loaded(module.name, page_module)

dash/dash.py

@@ -67,6 +67,7 @@
     _page_meta_tags,
     _path_to_page,
     _import_layouts_from_pages,
+    _import_layouts_from_package,
 )
 
 # Add explicit mapping for map files
@@ -345,6 +346,7 @@ def __init__(  # pylint: disable=too-many-statements
         server=True,
         assets_folder="assets",
         pages_folder="pages",
+        pages_package=None,
         use_pages=None,
         assets_url_path="assets",
         assets_ignore="",
@@ -444,6 +446,7 @@ def __init__(  # pylint: disable=too-many-statements
         _get_paths.CONFIG = self.config
         _pages.CONFIG = self.config
 
+        self.pages_package = pages_package
         self.pages_folder = str(pages_folder)
         self.use_pages = (pages_folder != "pages") if use_pages is None else use_pages
 
@@ -1959,6 +1962,8 @@ def enable_pages(self):
             return
         if self.pages_folder:
             _import_layouts_from_pages(self.config.pages_folder)
+        if self.pages_package:
+            _import_layouts_from_package(self.pages_package)
 
         @self.server.before_request
         def router():

tests/conftest.py

@@ -1,4 +1,5 @@
 import os
+import sys
 
 import pytest
 import dash
@@ -21,6 +22,8 @@ def clear_pages_state():
 
 def init_pages_state():
     """Clear all global state that is used by pages feature."""
+    for page in dash._pages.PAGE_REGISTRY.values():
+        sys.modules.pop(page["module"])
     dash._pages.PAGE_REGISTRY.clear()
     dash._pages.CONFIG.clear()
     dash._pages.CONFIG.__dict__.clear()

tests/unit/pages/test_pages.py

@@ -76,3 +76,12 @@ def test_import_layouts_from_pages(
 
     page_entry = list(dash.page_registry.values())[0]
     assert page_entry["module"] == expected_module_name
+
+
+def test_import_layouts_from_package(clear_pages_state):
+    from . import custom_pages
+
+    _ = Dash(__package__, use_pages=True, pages_folder="", pages_package=custom_pages)
+    page_entries = list(dash.page_registry.values())
+    assert len(page_entries) == 1
+    assert page_entries[0]["module"] == "pages.custom_pages.page"