API: Add exclude parameter to check-in lists

doc/api/resources/checkinlists.rst

@@ -58,7 +58,7 @@ rules                                 object                     Custom check-in
 
 .. versionchanged:: 3.11
 
-    The ``subevent_match`` filter has been added.
+    The ``subevent_match`` and ``exclude`` query parameters have been added.
 
 Endpoints
 ---------
@@ -114,6 +114,7 @@ Endpoints
    :query integer page: The page number in case of a multi-page result set, default is 1
    :query integer subevent: Only return check-in lists of the sub-event with the given ID
    :query integer subevent_match: Only return check-in lists that are valid for the sub-event with the given ID (i.e. also lists valid for all subevents)
+   :query string exclude: Exclude a field from the output, e.g. ``checkin_count``. Can be used as a performance optimization. Can be passed multiple times.
    :param organizer: The ``slug`` field of the organizer to fetch
    :param event: The ``slug`` field of the event to fetch
    :statuscode 200: no error

src/pretix/api/serializers/checkin.py

@@ -17,6 +17,17 @@ class CheckinListSerializer(I18nAwareModelSerializer):
                   'include_pending', 'auto_checkin_sales_channels', 'allow_multiple_entries', 'allow_entry_after_exit',
                   'rules')
 
+    def __init__(self, *args, **kwargs):
+        super().__init__(*args, **kwargs)
+
+        for exclude_field in self.context['request'].query_params.getlist('exclude'):
+            p = exclude_field.split('.')
+            if p[0] in self.fields:
+                if len(p) == 1:
+                    del self.fields[p[0]]
+                elif len(p) == 2:
+                    self.fields[p[0]].child.fields.pop(p[1])
+
     def validate(self, data):
         data = super().validate(data)
         event = self.context['event']