fix(route): don't let a splat catchall match paths sharing its prefix

news/6790.bugfix.md

@@ -0,0 +1 @@
+A `[[...splat]]` catchall route no longer matches paths that merely share its prefix — `posts/[[...splat]]` matched `/postsomething` as well as `/posts` and its descendants, so the wrong page's `on_load` events could fire.

reflex/route.py

@@ -172,7 +172,9 @@ def get_route_regex(keyworded_route: str) -> re.Pattern:
             # Match a single optional segment (/slug or nothing)
             regex_parts.append(r"(/[^/]+)?")
         elif part == constants.RouteRegex.DOUBLE_CATCHALL_SEGMENT:
-            regex_parts.append(".*")
+            # The frontend compiles this to React Router's `*`, which matches the
+            # route and its descendants only, so the segment separator is required.
+            regex_parts.append("(/.*)?")
         else:
             regex_parts.append(re.escape("/" + part))
     # Join the regex parts and compile the regex

tests/units/test_route.py

@@ -3,7 +3,7 @@
 from reflex_base import constants
 
 from reflex.app import App
-from reflex.route import get_route_args, verify_route_validity
+from reflex.route import get_route_args, get_router, verify_route_validity
 
 
 @pytest.mark.parametrize(
@@ -110,3 +110,20 @@ def test_check_routes_conflict_valid(mocker: MockerFixture, app, route1, route2)
     mocker.patch.object(app, "_pages", {route1: []})
     # test that running this does not throw an error.
     app._check_routes_conflict(route2)
+
+
+@pytest.mark.parametrize(
+    ("path", "expected"),
+    [
+        ("/posts", "posts/[[...splat]]"),
+        ("/posts/", "posts/[[...splat]]"),
+        ("/posts/2024/hello", "posts/[[...splat]]"),
+        ("/postsomething", None),
+        ("/posts-archive", None),
+    ],
+)
+def test_get_router_splat_catchall(path: str, expected: str | None):
+    # The frontend maps [[...splat]] to React Router's `posts/*`, which matches
+    # the route and its descendants but not paths that merely share the prefix.
+    router = get_router(["posts/[[...splat]]"])
+    assert router(path) == expected