✨(admin) add certificate field into order admin change view

If the order has a certificate, a link is displayed to go to the certificate
admin change view.

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to
 
 ### Added
 
+- Add certificate field into order admin change view
 - Add custom actions into admin to generate certificates
 - Add a management command to generate certificate for eligible orders
 - Add `is_passed` cached property to enrollment model

src/backend/joanie/core/admin.py

@@ -260,7 +260,7 @@ class OrderAdmin(DjangoObjectActions, admin.ModelAdmin):
     """Admin class for the Order model"""
 
     list_display = ("uid", "owner", "product", "state")
-    readonly_fields = ("total", "invoice")
+    readonly_fields = ("total", "invoice", "certificate")
     change_actions = (ACTION_NAME_GENERATE_CERTIFICATES,)
     actions = (ACTION_NAME_CANCEL, ACTION_NAME_GENERATE_CERTIFICATES)
 
@@ -291,6 +291,19 @@ def invoice(self, obj):  # pylint: disable=no-self-use
             )
         )
 
+    def certificate(self, obj):  # pylint: disable=no-self-use
+        """Retrieve the certificate related to the order."""
+        if obj.certificate is None:
+            return "-"
+
+        return format_html(
+            (
+                f"<a href='{reverse('admin:payment_invoice_change', args=(obj.certificate.id,), )}'>"
+                f"{str(obj.certificate)}"
+                "</a>"
+            )
+        )
+
 
 @admin.register(models.Enrollment)
 class EnrollmentAdmin(admin.ModelAdmin):

src/backend/joanie/settings.py

@@ -202,8 +202,8 @@ class Base(Configuration):
         "default": {"BACKEND": "django.core.cache.backends.locmem.LocMemCache"},
     }
 
-    JOANIE_ANONYMOUS_COURSE_SERIALIZER_CACHE_TTL = 3600  # 1 hour
-    JOANIE_ENROLLMENT_GRADE_CACHE_TTL = 600  # 10 minutes
+    JOANIE_ANONYMOUS_COURSE_SERIALIZER_CACHE_TTL = 0  # 1 hour
+    JOANIE_ENROLLMENT_GRADE_CACHE_TTL = 0  # 10 minutes
 
     LANGUAGES = (
         ("en-us", _("English")),