SpawnHandler POST with user form options displays the spawn-pending p…

…age just like the GET handler always did

jupyterhub/handlers/pages.py

@@ -151,17 +151,7 @@ async def get(self, for_user=None, server_name=''):
 
         spawner = user.spawners[server_name]
 
-        # resolve `?next=...`, falling back on the spawn-pending url
-        # must not be /user/server for named servers,
-        # which may get handled by the default server if they aren't ready yet
-
-        pending_url = url_path_join(
-            self.hub.base_url, "spawn-pending", user.escaped_name, server_name
-        )
-
-        if self.get_argument('next', None):
-            # preserve `?next=...` through spawn-pending
-            pending_url = url_concat(pending_url, {'next': self.get_argument('next')})
+        pending_url = self._get_pending_url(user, server_name)
 
         # spawner is active, redirect back to get progress, etc.
         if spawner.ready:
@@ -194,24 +184,7 @@ async def get(self, for_user=None, server_name=''):
             self.log.debug(
                 "Triggering spawn with default options for %s", spawner._log_name
             )
-            # Explicit spawn request: clear _spawn_future
-            # which may have been saved to prevent implicit spawns
-            # after a failure.
-            if spawner._spawn_future and spawner._spawn_future.done():
-                spawner._spawn_future = None
-            # not running, no form. Trigger spawn and redirect back to /user/:name
-            f = asyncio.ensure_future(self.spawn_single_user(user, server_name))
-            done, pending = await asyncio.wait([f], timeout=1)
-            # If spawn_single_user throws an exception, raise a 500 error
-            # otherwise it may cause a redirect loop
-            if f.done() and f.exception():
-                exc = f.exception()
-                raise web.HTTPError(
-                    500,
-                    "Error in Authenticator.pre_spawn_start: %s %s"
-                    % (type(exc).__name__, str(exc)),
-                )
-            self.redirect(pending_url)
+            return await self._wrap_spawn_single_user(user, server_name, spawner, pending_url)
 
     @web.authenticated
     async def post(self, for_user=None, server_name=''):
@@ -241,8 +214,12 @@ async def post(self, for_user=None, server_name=''):
         for key, byte_list in self.request.files.items():
             form_options["%s_file" % key] = byte_list
         try:
+            self.log.debug(
+                "Triggering spawn with supplied form options for %s", spawner._log_name
+            )
             options = await maybe_future(spawner.options_from_form(form_options))
-            await self.spawn_single_user(user, server_name=server_name, options=options)
+            pending_url = self._get_pending_url(user, server_name)
+            return await self._wrap_spawn_single_user(user, server_name, spawner, pending_url, options)
         except Exception as e:
             self.log.error(
                 "Failed to spawn single-user server with form", exc_info=True
@@ -263,6 +240,40 @@ async def post(self, for_user=None, server_name=''):
         )
         self.redirect(next_url)
 
+    def _get_pending_url(self, user, server_name):
+        # resolve `?next=...`, falling back on the spawn-pending url
+        # must not be /user/server for named servers,
+        # which may get handled by the default server if they aren't ready yet
+
+        pending_url = url_path_join(
+            self.hub.base_url, "spawn-pending", user.escaped_name, server_name
+        )
+
+        if self.get_argument('next', None):
+            # preserve `?next=...` through spawn-pending
+            pending_url = url_concat(pending_url, {'next': self.get_argument('next')})
+
+        return pending_url
+
+    async def _wrap_spawn_single_user(self, user, server_name, spawner, pending_url, options=None):
+        # Explicit spawn request: clear _spawn_future
+        # which may have been saved to prevent implicit spawns
+        # after a failure.
+        if spawner._spawn_future and spawner._spawn_future.done():
+            spawner._spawn_future = None
+        # not running, no form. Trigger spawn and redirect back to /user/:name
+        f = asyncio.ensure_future(self.spawn_single_user(user, server_name, options=options))
+        done, pending = await asyncio.wait([f], timeout=1)
+        # If spawn_single_user throws an exception, raise a 500 error
+        # otherwise it may cause a redirect loop
+        if f.done() and f.exception():
+            exc = f.exception()
+            raise web.HTTPError(
+                500,
+                "Error in Authenticator.pre_spawn_start: %s %s"
+                % (type(exc).__name__, str(exc)),
+                )
+        return self.redirect(pending_url)
 
 class SpawnPendingHandler(BaseHandler):
     """Handle /hub/spawn-pending/:user/:server