fix plus mixin for rest_framework 3.0
diff --git a/planetstack/core/xoslib/methods/plus.py b/planetstack/core/xoslib/methods/plus.py
index 1e4cdf5..9ace688 100644
--- a/planetstack/core/xoslib/methods/plus.py
+++ b/planetstack/core/xoslib/methods/plus.py
@@ -13,6 +13,8 @@
# This will cause a descendant class to pull in the methods defined
# above. See rest_framework/serializers.py: _get_declared_fields().
base_fields = {"backendIcon": backendIcon, "backendHtml": backendHtml}
+ # Rest_framework 3.0 uses _declared_fields instead of base_fields
+ _declared_fields = {"backendIcon": backendIcon, "backendHtml": backendHtml}
def getBackendIcon(self, obj):
return obj.getBackendIcon()