Change url_for signature to return a URL instance (#1385)

Co-authored-by: Marcelo Trylesinski <marcelotryle@gmail.com>

docs/routing.md

@@ -151,6 +151,8 @@ app = Starlette(routes=routes)
 You'll often want to be able to generate the URL for a particular route,
 such as in cases where you need to return a redirect response.
 
+* Signature: `url_for(name, **path_params) -> URL`
+
 ```python
 routes = [
     Route("/", homepage, name="homepage")

starlette/datastructures.py

@@ -187,7 +187,7 @@ def __init__(self, path: str, protocol: str = "", host: str = "") -> None:
         self.protocol = protocol
         self.host = host
 
-    def make_absolute_url(self, base_url: typing.Union[str, URL]) -> str:
+    def make_absolute_url(self, base_url: typing.Union[str, URL]) -> URL:
         if isinstance(base_url, str):
             base_url = URL(base_url)
         if self.protocol:
@@ -200,7 +200,7 @@ def make_absolute_url(self, base_url: typing.Union[str, URL]) -> str:
 
         netloc = self.host or base_url.netloc
         path = base_url.path.rstrip("/") + str(self)
-        return str(URL(scheme=scheme, netloc=netloc, path=path))
+        return URL(scheme=scheme, netloc=netloc, path=path)
 
 
 class Secret:

starlette/requests.py

@@ -173,7 +173,7 @@ def state(self) -> State:
             self._state = State(self.scope["state"])
         return self._state
 
-    def url_for(self, name: str, **path_params: typing.Any) -> str:
+    def url_for(self, name: str, **path_params: typing.Any) -> URL:
         router: Router = self.scope["router"]
         url_path = router.url_path_for(name, **path_params)
         return url_path.make_absolute_url(base_url=self.base_url)

starlette/templating.py

@@ -2,6 +2,7 @@
 from os import PathLike
 
 from starlette.background import BackgroundTask
+from starlette.datastructures import URL
 from starlette.requests import Request
 from starlette.responses import Response
 from starlette.types import Receive, Scope, Send
@@ -77,7 +78,7 @@ def _create_env(
         self, directory: typing.Union[str, PathLike], **env_options: typing.Any
     ) -> "jinja2.Environment":
         @pass_context
-        def url_for(context: dict, name: str, **path_params: typing.Any) -> str:
+        def url_for(context: dict, name: str, **path_params: typing.Any) -> URL:
             request = context["request"]
             return request.url_for(name, **path_params)
 

tests/test_routing.py

@@ -522,8 +522,8 @@ def test_subdomain_reverse_urls():
 async def echo_urls(request):
     return JSONResponse(
         {
-            "index": request.url_for("index"),
-            "submount": request.url_for("mount:submount"),
+            "index": str(request.url_for("index")),
+            "submount": str(request.url_for("mount:submount")),
         }
     )