From fac8e9381500fc02cec99281122ee8e0c72fabe1 Mon Sep 17 00:00:00 2001
From: Simon Willison <swillison@gmail.com>
Date: Mon, 8 Jun 2020 20:40:00 -0700
Subject: [PATCH] request.url_vars property, closes #822

---
 datasette/utils/asgi.py         |  4 ++++
 docs/internals.rst              |  3 +++
 docs/plugins.rst                |  4 ++--
 tests/plugins/my_plugin.py      |  4 ++--
 tests/test_internals_request.py | 17 +++++++++++++++++
 5 files changed, 28 insertions(+), 4 deletions(-)

diff --git a/datasette/utils/asgi.py b/datasette/utils/asgi.py
index 9e6c82dd..cdd6b148 100644
--- a/datasette/utils/asgi.py
+++ b/datasette/utils/asgi.py
@@ -32,6 +32,10 @@ class Request:
             (self.scheme, self.host, self.path, None, self.query_string, None)
         )
 
+    @property
+    def url_vars(self):
+        return (self.scope.get("url_route") or {}).get("kwargs") or {}
+
     @property
     def scheme(self):
         return self.scope.get("scheme") or "http"
diff --git a/docs/internals.rst b/docs/internals.rst
index b0096cfa..df21eb09 100644
--- a/docs/internals.rst
+++ b/docs/internals.rst
@@ -42,6 +42,9 @@ The request object is passed to various plugin hooks. It represents an incoming
 ``.args`` - MultiParams
     An object representing the parsed querystring parameters, see below.
 
+``.url_vars`` - dictionary (str -> str)
+    Variables extracted from the URL path, if that path was defined using a regular expression. See :ref:`plugin_register_routes`.
+
 ``.actor`` - dictionary (str -> Any) or None
     The currently authenticated actor (see :ref:`actors <authentication_actor>`), or ``None`` if the request is unauthenticated.
 
diff --git a/docs/plugins.rst b/docs/plugins.rst
index 465fcd52..17fd64df 100644
--- a/docs/plugins.rst
+++ b/docs/plugins.rst
@@ -850,8 +850,8 @@ Return a list of ``(regex, async_view_function)`` pairs, something like this:
     import html
 
 
-    async def hello_from(scope):
-        name = scope["url_route"]["kwargs"]["name"]
+    async def hello_from(request):
+        name = request.url_vars["name"]
         return Response.html("Hello from {}".format(
             html.escape(name)
         ))
diff --git a/tests/plugins/my_plugin.py b/tests/plugins/my_plugin.py
index 57803178..a0f7441b 100644
--- a/tests/plugins/my_plugin.py
+++ b/tests/plugins/my_plugin.py
@@ -152,8 +152,8 @@ def register_routes():
             (await datasette.get_database().execute("select 1 + 1")).first()[0]
         )
 
-    async def two(request, scope):
-        name = scope["url_route"]["kwargs"]["name"]
+    async def two(request):
+        name = request.url_vars["name"]
         greeting = request.args.get("greeting")
         return Response.text("{} {}".format(greeting, name))
 
diff --git a/tests/test_internals_request.py b/tests/test_internals_request.py
index 433b23d5..8367a693 100644
--- a/tests/test_internals_request.py
+++ b/tests/test_internals_request.py
@@ -44,3 +44,20 @@ def test_request_args():
     assert 2 == len(request.args)
     with pytest.raises(KeyError):
         request.args["missing"]
+
+
+def test_request_url_vars():
+    scope = {
+        "http_version": "1.1",
+        "method": "POST",
+        "path": "/",
+        "raw_path": b"/",
+        "query_string": b"",
+        "scheme": "http",
+        "type": "http",
+        "headers": [[b"content-type", b"application/x-www-form-urlencoded"]],
+    }
+    assert {} == Request(scope, None).url_vars
+    assert {"name": "cleo"} == Request(
+        dict(scope, url_route={"kwargs": {"name": "cleo"}}), None
+    ).url_vars