Add metric 'helpers_registered'

shiftregister/metrics/views.py

@@ -19,6 +19,25 @@ def metrics(request):
                         "helpers_confirmed_total",
                         Helper.objects.filter(number_validated=True).count(),
                     ),
+                    (
+                        "helpers_registered",
+                        Helper.objects.annotate(
+                            shift_count=Count(
+                                Case(
+                                    When(
+                                        shiftregistration__state__in=[
+                                            ShiftRegistration.RegState.REGISTERED,
+                                            ShiftRegistration.RegState.CHECKED_IN,
+                                        ],
+                                        then=1,
+                                    ),
+                                    output_field=models.IntegerField(),
+                                )
+                            )
+                        )
+                        .filter(number_validated=True, shift_count__gte=1)
+                        .count(),
+                    ),
                     (
                         "helpers_helped_total",
                         Helper.objects.annotate(