From c82b6835a009d57417551efe4da4ed677f724699 Mon Sep 17 00:00:00 2001
From: Matt Westcott <matthew@torchbox.com>
Date: Fri, 20 Apr 2018 08:02:29 +0100
Subject: [PATCH] Add a meaningful error message for invalid arguments to
 pageurl (#4228)

---
 wagtail/core/templatetags/wagtailcore_tags.py | 3 +++
 wagtail/core/tests/tests.py                   | 6 ++++++
 2 files changed, 9 insertions(+)

diff --git a/wagtail/core/templatetags/wagtailcore_tags.py b/wagtail/core/templatetags/wagtailcore_tags.py
index a66634b964..7f13ba27a7 100644
--- a/wagtail/core/templatetags/wagtailcore_tags.py
+++ b/wagtail/core/templatetags/wagtailcore_tags.py
@@ -16,6 +16,9 @@ def pageurl(context, page):
     Outputs a page's URL as relative (/foo/bar/) if it's within the same site as the
     current page, or absolute (http://example.com/foo/bar/) if not.
     """
+    if not hasattr(page, 'relative_url'):
+        raise ValueError("pageurl tag expected a Page object, got %r" % page)
+
     try:
         current_site = context['request'].site
     except (KeyError, AttributeError):
diff --git a/wagtail/core/tests/tests.py b/wagtail/core/tests/tests.py
index a730deb21d..ce8b001c37 100644
--- a/wagtail/core/tests/tests.py
+++ b/wagtail/core/tests/tests.py
@@ -37,6 +37,12 @@ class TestPageUrlTags(TestCase):
         result = tpl.render(template.Context({'page': page, 'request': HttpRequest()}))
         self.assertIn('<a href="/events/">Events</a>', result)
 
+    def test_bad_pageurl(self):
+        tpl = template.Template('''{% load wagtailcore_tags %}<a href="{% pageurl page %}">{{ page.title }}</a>''')
+
+        with self.assertRaisesRegex(ValueError, "pageurl tag expected a Page object, got None"):
+            tpl.render(template.Context({'page': None}))
+
     def test_slugurl_without_request_in_context(self):
         tpl = template.Template('''{% load wagtailcore_tags %}<a href="{% slugurl 'events' %}">Events</a>''')