Pagination improvements, allow to select page size

src/pretix/control/views/__init__.py

@@ -35,3 +35,24 @@ class ChartContainingView:
         # required by raphael.js
         resp['Content-Security-Policy'] = "script-src 'unsafe-eval'; style-src 'unsafe-inline'"
         return resp
+
+
+class PaginationMixin:
+    DEFAULT_PAGINATION = 25
+
+    def get_paginate_by(self, queryset):
+        skey = 'stored_page_size_' + self.request.resolver_match.url_name
+        default = self.request.session.get(skey) or self.paginate_by or self.DEFAULT_PAGINATION
+        if self.request.GET.get('page_size'):
+            try:
+                size = min(250, int(self.request.GET.get("page_size")))
+                self.request.session[skey] = size
+                return min(250, int(self.request.GET.get("page_size")))
+            except ValueError:
+                return default
+        return default
+
+    def get_context_data(self, **kwargs):
+        ctx = super().get_context_data(**kwargs)
+        ctx['page_size'] = self.get_paginate_by(None)
+        return ctx