Added fallback to pageurl (#4603)

CHANGELOG.txt

@@ -18,6 +18,7 @@ Changelog
  * Add Learn Wagtail to third-party tutorials in documentation (Matt Westcott)
  * Add a Django setting `TAG_LIMIT` to limit number of tags that can be added to any taggit model (Mani)
  * Added instructions on how to generate urls for `ModelAdmin` to documentation (LB (Ben Johnston), Andy Babic)
+ * Added option to specify a fallback URL on `{% pageurl %}` (Arthur Holzner)
  * Fix: Set `SERVER_PORT` to 443 in `Page.dummy_request()` for HTTPS sites (Sergey Fedoseev)
  * Fix: Include port number in `Host` header of `Page.dummy_request()` (Sergey Fedoseev)
  * Fix: Validation error messages in `InlinePanel` no longer count towards `max_num` when disabling the 'add' button (Todd Dembrey, Thibaud Colas)

docs/releases/2.5.rst

@@ -28,6 +28,7 @@ Other features
  * Add Learn Wagtail to third-party tutorials in documentation (Matt Westcott)
  * Add a Django setting ``TAG_LIMIT`` to limit number of tags that can be added to any taggit model (Mani)
  * Added instructions on how to generate urls for ``ModelAdmin`` to documentation (LB (Ben Johnston), Andy Babic)
+ * Added option to specify a fallback URL on ``{% pageurl %}`` (Arthur Holzner)
 
 
 Bug fixes

docs/topics/writing_templates.rst

@@ -160,7 +160,23 @@ Takes a Page object and returns a relative URL (``/foo/bar/``) if within the sam
 
     {% load wagtailcore_tags %}
     ...
-    <a href="{% pageurl page.blog_page %}">
+    <a href="{% pageurl page.get_parent %}">Back to index</a>
+
+
+A ``fallback`` keyword argument can be provided - this should be a URL route name that takes no parameters, and will be used as a substitute URL when the passed page is ``None``.
+
+.. code-block:: html+django
+
+    {% load wagtailcore_tags %}
+
+    {% for publication in page.related_publications.all %}
+        <li>
+            <a href="{% pageurl publication.detail_page fallback='coming_soon' %}">
+                {{ publication.title }}
+            </a>
+        </li>
+    {% endfor %}
+
 
 .. _slugurl_tag:
 

wagtail/core/templatetags/wagtailcore_tags.py

@@ -1,4 +1,5 @@
 from django import template
+from django.shortcuts import reverse
 from django.template.defaulttags import token_kwargs
 from django.utils.encoding import force_text
 from django.utils.safestring import mark_safe
@@ -12,11 +13,15 @@ register = template.Library()
 
 
 @register.simple_tag(takes_context=True)
-def pageurl(context, page):
+def pageurl(context, page, fallback=None):
     """
     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 kwargs contains a fallback view name and page is None, the fallback view url will be returned.
     """
+    if page is None and fallback:
+        return reverse(fallback)
+
     if not hasattr(page, 'relative_url'):
         raise ValueError("pageurl tag expected a Page object, got %r" % page)
 

wagtail/core/tests/tests.py

@@ -2,6 +2,7 @@ from django import template
 from django.core.cache import cache
 from django.http import HttpRequest
 from django.test import TestCase
+from django.urls.exceptions import NoReverseMatch
 from django.utils.safestring import SafeText
 
 from wagtail.core.models import Page, Site
@@ -19,6 +20,16 @@ class TestPageUrlTags(TestCase):
         self.assertContains(response,
                             '<a href="/events/christmas/">Christmas</a>')
 
+    def test_pageurl_fallback(self):
+        tpl = template.Template('''{% load wagtailcore_tags %}<a href="{% pageurl page fallback='fallback' %}">Fallback</a>''')
+        result = tpl.render(template.Context({'page': None}))
+        self.assertIn('<a href="/fallback/">Fallback</a>', result)
+
+    def test_pageurl_fallback_without_valid_fallback(self):
+        tpl = template.Template('''{% load wagtailcore_tags %}<a href="{% pageurl page fallback='not-existing-endpoint' %}">Fallback</a>''')
+        with self.assertRaises(NoReverseMatch):
+            tpl.render(template.Context({'page': None}))
+
     def test_slugurl_tag(self):
         response = self.client.get('/events/christmas/')
         self.assertEqual(response.status_code, 200)

wagtail/tests/urls.py

@@ -1,4 +1,5 @@
 from django.conf.urls import include, url
+from django.http import HttpResponse
 
 from wagtail.admin import urls as wagtailadmin_urls
 from wagtail.api.v2.endpoints import PagesAPIEndpoint
@@ -37,6 +38,8 @@ urlpatterns = [
 
     url(r'^testapp/', include(testapp_urls)),
 
+    url(r'^fallback/', lambda: HttpResponse('ok'), name='fallback'),
+
     # For anything not caught by a more specific rule above, hand over to
     # Wagtail's serving mechanism
     url(r'', include(wagtail_urls)),