manager: do not crash on page configured with a missing template (#23186)

combo/data/models.py

@@ -44,7 +44,7 @@ from django.utils.safestring import mark_safe
 from django.utils.text import slugify
 from django.utils.translation import ugettext_lazy as _
 from django.forms.widgets import MediaDefiningClass
-from django.template import Context, engines
+from django.template import Context, engines, TemplateDoesNotExist
 from django.test.client import RequestFactory
 
 from .fields import RichTextField
@@ -215,6 +215,14 @@ class Page(models.Model):
     def get_template_display_name(self):
         return settings.COMBO_PUBLIC_TEMPLATES[self.template_name]['name']
 
+    def missing_template(self):
+        template_name = settings.COMBO_PUBLIC_TEMPLATES.get(self.template_name).get('template')
+        try:
+            template.loader.select_template([template_name])
+        except TemplateDoesNotExist:
+            return True
+        return False
+
     def get_placeholders(self, request, traverse_cells=False, template_name=None):
         placeholders = []
 
@@ -226,7 +234,7 @@ class Page(models.Model):
             return placeholders
 
         template_name = settings.COMBO_PUBLIC_TEMPLATES.get(self.template_name).get('template')
-        tmpl = template.loader.select_template([template_name])
+        tmpl = template.loader.select_template([template_name, 'combo/page_template.html'])
         request = RequestFactory(SERVER_NAME=request.get_host()).get(self.get_online_url())
         request.user = None
         context = {

combo/manager/static/css/combo.manager.css

@@ -365,3 +365,8 @@ span.extra-info {
 img.page-picture {
 	max-width: 100%;
 }
+
+span.error {
+	color: red;
+	font-weight: bold;
+}

combo/manager/templates/combo/page_view.html

@@ -43,6 +43,7 @@
 <p>
 <label>{% trans 'Template:' %}</label>
 {{ object.get_template_display_name }}
+{% if object.missing_template %}<span class="error">({% trans "missing" %})</span>{% endif %}
 (<a rel="popup" href="{% url 'combo-manager-page-select-template' pk=object.id %}">{% trans 'change' %}</a>)
 </p>