Closes #1237: Enabled setting limit=0 to disable pagination in API requests; added MAX_PAGE_SIZE configuration setting

netbox/utilities/api.py

@@ -5,6 +5,7 @@ from django.contrib.contenttypes.models import ContentType
 
 from rest_framework import authentication, exceptions
 from rest_framework.exceptions import APIException
+from rest_framework.pagination import LimitOffsetPagination
 from rest_framework.permissions import DjangoModelPermissions, SAFE_METHODS
 from rest_framework.serializers import Field, ValidationError
 
@@ -105,3 +106,51 @@ class WritableSerializerMixin(object):
         if self.action in WRITE_OPERATIONS and hasattr(self, 'write_serializer_class'):
             return self.write_serializer_class
         return self.serializer_class
+
+
+class OptionalLimitOffsetPagination(LimitOffsetPagination):
+    """
+    Override the stock paginator to allow setting limit=0 to disable pagination for a request. This returns all objects
+    matching a query, but retains the same format as a paginated request. The limit can only be disabled if
+    MAX_PAGE_SIZE has been set to 0 or None.
+    """
+
+    def paginate_queryset(self, queryset, request, view=None):
+
+        try:
+            self.count = queryset.count()
+        except (AttributeError, TypeError):
+            self.count = len(queryset)
+        self.limit = self.get_limit(request)
+        self.offset = self.get_offset(request)
+        self.request = request
+
+        if self.limit and self.count > self.limit and self.template is not None:
+            self.display_page_controls = True
+
+        if self.count == 0 or self.offset > self.count:
+            return list()
+
+        if self.limit:
+            return list(queryset[self.offset:self.offset + self.limit])
+        else:
+            return list(queryset[self.offset:])
+
+    def get_limit(self, request):
+
+        if self.limit_query_param:
+            try:
+                limit = int(request.query_params[self.limit_query_param])
+                if limit < 0:
+                    raise ValueError()
+                # Enforce maximum page size, if defined
+                if settings.MAX_PAGE_SIZE:
+                    if limit == 0:
+                        return settings.MAX_PAGE_SIZE
+                    else:
+                        return min(limit, settings.MAX_PAGE_SIZE)
+                return limit
+            except (KeyError, ValueError):
+                pass
+
+        return self.default_limit