From eb92a382786c66b1e461f0864efa78d851e57f69 Mon Sep 17 00:00:00 2001
From: Philippe Duval <philippe@plot.ly>
Date: Thu, 26 Jul 2018 12:14:59 -0400
Subject: [PATCH] Add `external_js/css_urls` to dash ctor, support for external
 only urls

---
 dash/dash.py              | 13 ++++++++++++-
 dash/resources.py         |  3 ++-
 tests/test_integration.py | 24 +++++++++++++++++++++++-
 3 files changed, 37 insertions(+), 3 deletions(-)

diff --git a/dash/dash.py b/dash/dash.py
index 44fad1efee..0780e8bd59 100644
--- a/dash/dash.py
+++ b/dash/dash.py
@@ -9,6 +9,7 @@
 import warnings
 import re
 
+import itertools
 from functools import wraps
 
 import plotly
@@ -61,7 +62,7 @@
 
 
 # pylint: disable=too-many-instance-attributes
-# pylint: disable=too-many-arguments
+# pylint: disable=too-many-arguments, too-many-locals
 class Dash(object):
     def __init__(
             self,
@@ -75,6 +76,8 @@ def __init__(
             compress=True,
             meta_tags=None,
             index_string=_default_index,
+            external_script_urls=None,
+            external_css_urls=None,
             **kwargs):
 
         # pylint-disable: too-many-instance-attributes
@@ -128,6 +131,14 @@ def _handle_error(error):
         # static files from the packages
         self.css = Css()
         self.scripts = Scripts()
+
+        for method, resource in itertools.chain(
+                ((self.scripts.append_script, x)
+                 for x in (external_script_urls or [])),
+                ((self.css.append_css, x)
+                 for x in (external_css_urls or []))):
+            method({'external_url': resource, 'external_only': True})
+
         self.registered_paths = {}
 
         # urls
diff --git a/dash/resources.py b/dash/resources.py
index 70f37a5389..f17b3e3555 100644
--- a/dash/resources.py
+++ b/dash/resources.py
@@ -21,7 +21,8 @@ def _filter_resources(self, all_resources):
             filtered_resource = {}
             if 'namespace' in s:
                 filtered_resource['namespace'] = s['namespace']
-            if 'external_url' in s and not self.config.serve_locally:
+            if 'external_url' in s and (
+                    not self.config.serve_locally or s.get('external_only')):
                 filtered_resource['external_url'] = s['external_url']
             elif 'relative_package_path' in s:
                 filtered_resource['relative_package_path'] = (
diff --git a/tests/test_integration.py b/tests/test_integration.py
index 770b9152cb..aef8f05ffd 100644
--- a/tests/test_integration.py
+++ b/tests/test_integration.py
@@ -434,4 +434,26 @@ def will_raise():
         self.assertTrue('{%config%}' in exc_msg)
         self.assertTrue('{%scripts%}' in exc_msg)
         time.sleep(0.5)
-        print('invalid index string')
+
+    def test_external_files_init(self):
+        js_files = [
+            'https://www.google-analytics.com/analytics.js',
+            'https://cdn.polyfill.io/v2/polyfill.min.js'
+        ]
+        css_files = [
+            'https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css',
+            'https://codepen.io/chriddyp/pen/bWLwgP.css'
+        ]
+
+        app = dash.Dash(
+            external_script_urls=js_files, external_css_urls=css_files)
+
+        app.layout = html.Div()
+
+        self.startServer(app)
+        time.sleep(0.5)
+
+        for fmt, url in itertools.chain(
+                (("//script[@src='{}']", x) for x in js_files),
+                (("//link[@href='{}']", x) for x in css_files)):
+            self.driver.find_element_by_xpath(fmt.format(url))