Merge pull request #570 from geoadmin/bug-PB-1615-property-upload-url

PB-1615: Fix change form template variable lookup error

Author: msom

app/stac_api/templatetags/__init__.py

@@ -0,0 +1,20 @@
+from django import template
+
+register = template.Library()
+
+
+@register.simple_tag(takes_context=True)
+def get_context_variable(context, name, default):
+    """Retrieve a context variable from the template context, returning a default value if the
+    variable is not defined.
+
+    Accessing undefined variables will still render the template, but using this function prevents
+    unnecessary stack traces in the logs.
+
+    Use this tag in a template like this:
+
+    {% get_context_variable '<name>' <default> as <name> %}
+    {{ name }}
+
+    """
+    return context.get(name, default)

app/stac_api/templatetags/context_variables.py

@@ -1,6 +1,8 @@
 {% extends "admin/change_form.html" %}
 {% load i18n admin_urls %}
+{% load context_variables %}
 {% block object-tools-items %}
+    {% get_context_variable 'property_upload_url' None as property_upload_url %}
     {% if property_upload_url %}
         <li>
             <a href="upload/" class="historylink">Upload file</a>