🔧 handle prefixes in the middle of the supplied paths

and paths that look like request_pathname_prefix but don’t have the
trailing slash

Author: chriddyp

dash/_utils.py

@@ -75,14 +75,27 @@ def get_relative_path(requests_pathname, path):
 def strip_relative_path(requests_pathname, path):
     if path is None:
         return None
-    elif not path.startswith('/'):
+    elif ((requests_pathname != '/' and
+            not path.startswith(requests_pathname.rstrip('/')))
+            or (requests_pathname == '/' and not path.startswith('/'))):
         raise exceptions.UnsupportedRelativePath(
-            "Paths that aren't prefixed with a leading / are not supported.\n" +
-            "You supplied: {}".format(path)
+            "Paths that aren't prefixed with a leading " +
+            "requests_pathname_prefix are not supported.\n" +
+            "You supplied: {} and requests_pathname_prefix was {}".format(
+                path,
+                requests_pathname
+            )
+        )
+    if (requests_pathname != '/' and
+            path.startswith(requests_pathname.rstrip('/'))):
+        path = path.replace(
+            # handle the case where the path might be `/my-dash-app`
+            # but the requests_pathname_prefix is `/my-dash-app/`
+            requests_pathname.rstrip('/'),
+            '',
+            1
         )
-    if requests_pathname != '/':
-        path = path.replace(requests_pathname, '')
-    return path.lstrip('/').rstrip('/')
+    return path.strip('/')
 
 
 # pylint: disable=no-member

tests/unit/test_configs.py

@@ -203,7 +203,8 @@ def test_invalid_get_relative_path(prefix, partial_path):
         ("/my-dash-app/", None, None),
 
         ("/", "/", ""),
-        ("/my-dash-app/", "/", ""),
+        ("/my-dash-app/", "/my-dash-app", ""),
+        ("/my-dash-app/", "/my-dash-app/", ""),
 
         ("/", "/page-1", "page-1"),
         ("/my-dash-app/", "/my-dash-app/page-1", "page-1"),
@@ -216,6 +217,9 @@ def test_invalid_get_relative_path(prefix, partial_path):
 
         ("/", "/page-1/sub-page-1/", "page-1/sub-page-1"),
         ("/my-dash-app/", "/my-dash-app/page-1/sub-page-1/", "page-1/sub-page-1"),
+
+        ("/my-dash-app/", "/my-dash-app/my-dash-app/", "my-dash-app"),
+        ("/my-dash-app/", "/my-dash-app/something-else/my-dash-app/", "something-else/my-dash-app"),
     ]
 )
 def test_strip_relative_path(prefix, partial_path, expected):
@@ -228,6 +232,7 @@ def test_strip_relative_path(prefix, partial_path, expected):
     [
         ("/", "relative-page-1"),
         ("/my-dash-app", "relative-page-1"),
+        ("/my-dash-app", "/some-other-path")
     ]
 )
 def test_invalid_strip_relative_path(prefix, partial_path):