🐛 fix importing middleware

spiderweb/middleware/__init__.py

@@ -2,9 +2,6 @@ from typing import Callable, ClassVar
 import sys
 
 from .base import SpiderwebMiddleware as SpiderwebMiddleware
-from .cors import CorsMiddleware as CorsMiddleware
-from .csrf import CSRFMiddleware as CSRFMiddleware
-from .sessions import SessionMiddleware as SessionMiddleware
 from ..exceptions import ConfigError, UnusedMiddleware, StartupErrors
 from ..request import Request
 from ..response import HttpResponse

spiderweb/tests/test_middleware.py

@@ -4,7 +4,7 @@ from datetime import timedelta
 import pytest
 from peewee import SqliteDatabase
 
-from spiderweb import SpiderwebRouter, HttpResponse, StartupErrors
+from spiderweb import SpiderwebRouter, HttpResponse, StartupErrors, ConfigError
 from spiderweb.constants import DEFAULT_ENCODING
 from spiderweb.middleware.cors import (
     ACCESS_CONTROL_ALLOW_ORIGIN,
@@ -94,6 +94,13 @@ def test_exploding_middleware():
     assert len(app.middleware) == 0
 
 
+def test_invalid_middleware():
+    with pytest.raises(ConfigError) as e:
+        SpiderwebRouter(middleware=["nonexistent.middleware"])
+
+    assert e.value.args[0] == "Middleware 'nonexistent.middleware' not found."
+
+
 def test_csrf_middleware_without_session_middleware():
     with pytest.raises(StartupErrors) as e:
         SpiderwebRouter(

spiderweb/utils.py

@@ -1,3 +1,4 @@
+import importlib
 import json
 import re
 import secrets
@@ -13,12 +14,10 @@ VALID_CHARS = string.ascii_letters + string.digits
 
 
 def import_by_string(name):
-    # https://stackoverflow.com/a/547867
-    components = name.split(".")
-    mod = __import__(components[0])
-    for comp in components[1:]:
-        mod = getattr(mod, comp)
-    return mod
+    mod_name, klass_name = name.rsplit(".", 1)
+    module = importlib.import_module(mod_name)
+    klass = getattr(module, klass_name)
+    return klass
 
 
 def is_safe_path(path: str) -> bool: