Fix imports of modules by Dash Pages feature

dash/_pages.py

@@ -1,11 +1,11 @@
-import os
-from os import listdir
-from os.path import isfile, join
 import collections
-from urllib.parse import parse_qs
-from fnmatch import fnmatch
+import os
 import re
+import sys
+from fnmatch import fnmatch
 from pathlib import Path
+from os.path import isfile, join
+from urllib.parse import parse_qs
 
 import flask
 
@@ -34,7 +34,7 @@ def _infer_image(module):
 
     if os.path.exists(assets_folder):
         files_in_assets = [
-            f for f in listdir(assets_folder) if isfile(join(assets_folder, f))
+            f for f in os.listdir(assets_folder) if isfile(join(assets_folder, f))
         ]
     app_file = None
     logo_file = None
@@ -66,9 +66,9 @@ def _module_name_to_page_name(module_name):
 def _infer_path(module_name, template):
     if template is None:
         if CONFIG.pages_folder:
-            pages_folder = str(Path(CONFIG.pages_folder).name)
+            pages_module = str(Path(CONFIG.pages_folder).name)
             path = (
-                module_name.split(pages_folder)[-1]
+                module_name.split(pages_module)[-1]
                 .replace("_", "-")
                 .replace(".", "/")
                 .lower()
@@ -83,6 +83,29 @@ def _infer_path(module_name, template):
     return path
 
 
+def _module_name_is_package(module_name):
+    return (
+        module_name in sys.modules
+        and Path(sys.modules[module_name].__file__).name == "__init__.py"
+    )
+
+
+def _infer_module_name(page_path):
+    page_path = page_path.replace("\\", "/")
+    _, _, filename = page_path.partition(CONFIG.pages_folder.replace("\\", "/") + "/")
+    module = filename.replace(".py", "").replace("/", ".")
+    proj_root = flask.helpers.get_root_path(CONFIG.name)
+    parent_module = CONFIG.pages_folder
+    if CONFIG.pages_folder.startswith(proj_root):
+        parent_module = parent_module[len(proj_root) :]
+    parent_module = parent_module.lstrip("/").replace("/", ".")
+    module_name = f"{parent_module}.{module}"
+    if _module_name_is_package(CONFIG.name):
+        # Only prefix with CONFIG.name when its an imported package name
+        module_name = f"{CONFIG.name}.{module_name}"
+    return module_name
+
+
 def _parse_query_string(search):
     if search and len(search) > 0 and search[0] == "?":
         search = search[1:]

dash/dash.py

@@ -64,6 +64,7 @@
 
 from . import _pages
 from ._pages import (
+    _infer_module_name,
     _parse_path_variables,
     _parse_query_string,
 )
@@ -1987,9 +1988,7 @@ def verify_url_part(served_part, url_part, part_name):
         self.server.run(host=host, port=port, debug=debug, **flask_run_options)
 
     def _import_layouts_from_pages(self):
-        walk_dir = self.config.pages_folder
-
-        for (root, dirs, files) in os.walk(walk_dir):
+        for root, dirs, files in os.walk(self.config.pages_folder):
             dirs[:] = [
                 d for d in dirs if not d.startswith(".") and not d.startswith("_")
             ]
@@ -2000,29 +1999,17 @@ def _import_layouts_from_pages(self):
                     or not file.endswith(".py")
                 ):
                     continue
-                with open(os.path.join(root, file), encoding="utf-8") as f:
+                page_path = os.path.join(root, file)
+                with open(page_path, encoding="utf-8") as f:
                     content = f.read()
                     if "register_page" not in content:
                         continue
 
-                page_filename = os.path.join(root, file).replace("\\", "/")
-                _, _, page_filename = page_filename.partition(
-                    walk_dir.replace("\\", "/") + "/"
-                )
-                page_filename = page_filename.replace(".py", "").replace("/", ".")
-
-                proj_root = flask.helpers.get_root_path(self.config.name)
-                parent_module = self.config.pages_folder
-                if self.config.pages_folder.startswith(proj_root):
-                    parent_module = parent_module[len(proj_root) :]
-                parent_module = parent_module.lstrip("/").replace("/", ".")
-                module_name = f"{parent_module}.{page_filename}"
-
-                spec = importlib.util.spec_from_file_location(
-                    module_name, os.path.join(root, file)
-                )
+                module_name = _infer_module_name(page_path)
+                spec = importlib.util.spec_from_file_location(module_name, page_path)
                 page_module = importlib.util.module_from_spec(spec)
                 spec.loader.exec_module(page_module)
+                sys.modules[module_name] = page_module
 
                 if (
                     module_name in _pages.PAGE_REGISTRY

tests/unit/pages/test_pages.py

@@ -1,9 +1,10 @@
+import sys
 from pathlib import Path
 
 import pytest
 import dash
 from dash import Dash, _pages
-from mock import patch
+from mock import patch, Mock
 
 
 THIS_DIR = Path(__file__).parent
@@ -36,17 +37,18 @@ def test_infer_path(clear_pages_state, module_name, template, pages_folder, expe
 
 
 @pytest.mark.parametrize(
-    "pages_folder, expected_module_name",
+    "name, pages_folder, expected_module_name",
     [
-        ("custom_pages", "custom_pages.page"),
-        ("sub_dir/custom_pages", "sub_dir.custom_pages.page"),
-        (str(THIS_DIR / "custom_pages"), "custom_pages.page"),
+        (__name__, "custom_pages", "custom_pages.page"),
+        (__name__, "sub_dir/custom_pages", "sub_dir.custom_pages.page"),
+        (__name__, str(THIS_DIR / "custom_pages"), "custom_pages.page"),
+        (__package__, "custom_pages", "pages.custom_pages.page"),
     ],
 )
 def test_import_layouts_from_pages(
-    clear_pages_state, pages_folder, expected_module_name
+    clear_pages_state, name, pages_folder, expected_module_name
 ):
-    _ = Dash(__name__, use_pages=True, pages_folder=pages_folder)
+    _ = Dash(name, use_pages=True, pages_folder=pages_folder)
     assert len(dash.page_registry) == 1
 
     page_entry = list(dash.page_registry.values())[0]