Use relative path based on notebook for html import loads.

(c) Copyright IBM Corp. 2015

nb-extension/js/main.js

@@ -6,6 +6,19 @@ define([
     './init/init'
 ], function(init) {
     'use strict';
-    init(IPython.notebook.base_url + 'urth_components');
+    // Default the root directory for bower_components to be
+    // the notebook base url, but use the base of the current
+    // url instead as long as it is valid. This is done so that
+    // on init, the HTML imports are loaded from the same
+    // url that will be used for HTML imports in cells of the
+    // notebook. Doing this allows the browser to recognize the
+    // resource has already been retrieved and prevents double
+    // initialization of polymer and elements.
+    var bower_root = IPython.notebook.base_url;
+    var slashIndex = window.location.href.lastIndexOf('/');
+    if (slashIndex > 0) {
+        bower_root = window.location.href.substr(0, slashIndex + 1);
+    }
+    init(bower_root + 'urth_components');
     console.debug('Custom JS loaded');
 });

nb-extension/python/urth/widgets/urth_import.py

@@ -80,7 +80,7 @@ def post(self):
             msg = 'Failed to open bower.json for {0}.'.format(package_name)
             raise tornado.web.HTTPError(404, msg, reason=msg)
 
-class ComponentsRedirectHandler(RequestHandler): 
+class ComponentsRedirectHandler(RequestHandler):
     def get(self, path):
         '''
         Redirect relative requests for components to the global store. Makes
@@ -100,12 +100,13 @@ def load_jupyter_server_extension(nb_app):
         if ipython_dir in path:
             nbext = path
     import_route_pattern = url_path_join(web_app.settings['base_url'], '/urth_import')
-    components_route_pattern = url_path_join(web_app.settings['base_url'], '/urth_components/(.*)')
-    components_redirect_route_pattern = url_path_join(web_app.settings['base_url'], '/notebooks/.*/urth_components/(.*)')
+
+    # Any requests containing /urth_components/ will get served from the bower_components
+    # directory.
+    components_route_pattern = url_path_join(web_app.settings['base_url'], '.*/urth_components/(.*)')
     path = os.path.join(nbext, 'urth_widgets/bower_components/')
+
     web_app.add_handlers(host_pattern, [
         (import_route_pattern, UrthImportHandler),
-        (components_route_pattern, FileFindHandler, {'path': [path]}),
-        (components_redirect_route_pattern, ComponentsRedirectHandler)
+        (components_route_pattern, FileFindHandler, {'path': [path]})
     ])
-

notebooks/examples/urth-core-bind.ipynb

@@ -398,7 +398,7 @@
    "outputs": [],
    "source": [
     "%%html\n",
-    "<link rel='import' href='/urth_components/paper-slider/paper-slider.html'\n",
+    "<link rel='import' href='urth_components/paper-slider/paper-slider.html'\n",
     "        is='urth-core-import' package='PolymerElements/paper-slider'>"
    ]
   },