fix: set correct path_template value for trie node (#3806)

litestar/_asgi/routing_trie/mapping.py

@@ -111,7 +111,7 @@ def add_route_to_trie(
                 next_node_key = component
 
             if next_node_key not in current_node.children:
-                current_node.children[next_node_key] = create_node(path_template=route.path_format)
+                current_node.children[next_node_key] = create_node()
 
             current_node.child_keys = set(current_node.children.keys())
             current_node = current_node.children[next_node_key]
@@ -140,6 +140,7 @@ def configure_node(
     """
     from litestar.routes import HTTPRoute, WebSocketRoute
 
+    node.path_template = route.path_format
     if not node.path_parameters:
         node.path_parameters = {}
 

litestar/_asgi/routing_trie/types.py

@@ -34,9 +34,9 @@ class RouteTrieNode:
         "children",
         "is_asgi",
         "is_mount",
-        "is_static",
         "is_path_param_node",
         "is_path_type",
+        "is_static",
         "path_parameters",
         "path_template",
     )
@@ -68,7 +68,7 @@ class RouteTrieNode:
     """The path template string used to lower prometheus cardinality when group_path enabled"""
 
 
-def create_node(path_template: str = "") -> RouteTrieNode:
+def create_node() -> RouteTrieNode:
     """Create a RouteMapNode instance.
 
     Returns:
@@ -85,5 +85,5 @@ def create_node(path_template: str = "") -> RouteTrieNode:
         is_static=False,
         is_path_type=False,
         path_parameters={},
-        path_template=path_template,
+        path_template="",
     )

tests/examples/test_contrib/prometheus/test_prometheus_exporter_example.py

@@ -3,7 +3,7 @@
 import pytest
 from prometheus_client import REGISTRY
 
-from litestar import get
+from litestar import Controller, Litestar, Request, get
 from litestar.contrib.prometheus import PrometheusMiddleware
 from litestar.status_codes import HTTP_200_OK
 from litestar.testing import TestClient
@@ -60,3 +60,25 @@ def home(name: str) -> Dict[str, Any]:
         assert metrics_exporter_response.status_code == HTTP_200_OK
         metrics = metrics_exporter_response.content.decode()
         assert expected_path in metrics
+
+
+def test_correct_population_path_template() -> None:
+    class TestController(Controller):
+        path = "/prefix"
+
+        @get("/{id_:int}")
+        async def b(self, request: Request, id_: int) -> str:
+            return request.scope["path_template"]
+
+        @get("/{id_:int}/postfix")
+        async def a(self, request: Request, id_: int) -> str:
+            return request.scope["path_template"]
+
+    app = Litestar([TestController])
+
+    with TestClient(app) as client:
+        without_postfix_resp = client.get("/prefix/1")
+        with_postfix_resp = client.get("/prefix/1/postfix")
+
+        assert without_postfix_resp.content.decode() == "/prefix/{id_}"
+        assert with_postfix_resp.content.decode() == "/prefix/{id_}/postfix"